diff --git a/ext/digest/crc12_3gpp/crc12_3gpp.c b/ext/digest/crc12_3gpp/crc12_3gpp.c
index 983229d..638691d 100644
--- a/ext/digest/crc12_3gpp/crc12_3gpp.c
+++ b/ext/digest/crc12_3gpp/crc12_3gpp.c
@@ -15,52 +15,42 @@
  */
 
 #include "crc12_3gpp.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc12_t crc12_table[256] = {
-    0x000, 0x80f, 0x811, 0x01e, 0x82d, 0x022, 0x03c, 0x833, 0x855, 0x05a, 0x044, 0x84b, 0x078, 0x877, 0x869, 0x066,
-    0x8a5, 0x0aa, 0x0b4, 0x8bb, 0x088, 0x887, 0x899, 0x096, 0x0f0, 0x8ff, 0x8e1, 0x0ee, 0x8dd, 0x0d2, 0x0cc, 0x8c3,
-    0x945, 0x14a, 0x154, 0x95b, 0x168, 0x967, 0x979, 0x176, 0x110, 0x91f, 0x901, 0x10e, 0x93d, 0x132, 0x12c, 0x923,
-    0x1e0, 0x9ef, 0x9f1, 0x1fe, 0x9cd, 0x1c2, 0x1dc, 0x9d3, 0x9b5, 0x1ba, 0x1a4, 0x9ab, 0x198, 0x997, 0x989, 0x186,
-    0xa85, 0x28a, 0x294, 0xa9b, 0x2a8, 0xaa7, 0xab9, 0x2b6, 0x2d0, 0xadf, 0xac1, 0x2ce, 0xafd, 0x2f2, 0x2ec, 0xae3,
-    0x220, 0xa2f, 0xa31, 0x23e, 0xa0d, 0x202, 0x21c, 0xa13, 0xa75, 0x27a, 0x264, 0xa6b, 0x258, 0xa57, 0xa49, 0x246,
-    0x3c0, 0xbcf, 0xbd1, 0x3de, 0xbed, 0x3e2, 0x3fc, 0xbf3, 0xb95, 0x39a, 0x384, 0xb8b, 0x3b8, 0xbb7, 0xba9, 0x3a6,
-    0xb65, 0x36a, 0x374, 0xb7b, 0x348, 0xb47, 0xb59, 0x356, 0x330, 0xb3f, 0xb21, 0x32e, 0xb1d, 0x312, 0x30c, 0xb03,
-    0xd05, 0x50a, 0x514, 0xd1b, 0x528, 0xd27, 0xd39, 0x536, 0x550, 0xd5f, 0xd41, 0x54e, 0xd7d, 0x572, 0x56c, 0xd63,
-    0x5a0, 0xdaf, 0xdb1, 0x5be, 0xd8d, 0x582, 0x59c, 0xd93, 0xdf5, 0x5fa, 0x5e4, 0xdeb, 0x5d8, 0xdd7, 0xdc9, 0x5c6,
-    0x440, 0xc4f, 0xc51, 0x45e, 0xc6d, 0x462, 0x47c, 0xc73, 0xc15, 0x41a, 0x404, 0xc0b, 0x438, 0xc37, 0xc29, 0x426,
-    0xce5, 0x4ea, 0x4f4, 0xcfb, 0x4c8, 0xcc7, 0xcd9, 0x4d6, 0x4b0, 0xcbf, 0xca1, 0x4ae, 0xc9d, 0x492, 0x48c, 0xc83,
-    0x780, 0xf8f, 0xf91, 0x79e, 0xfad, 0x7a2, 0x7bc, 0xfb3, 0xfd5, 0x7da, 0x7c4, 0xfcb, 0x7f8, 0xff7, 0xfe9, 0x7e6,
-    0xf25, 0x72a, 0x734, 0xf3b, 0x708, 0xf07, 0xf19, 0x716, 0x770, 0xf7f, 0xf61, 0x76e, 0xf5d, 0x752, 0x74c, 0xf43,
-    0xec5, 0x6ca, 0x6d4, 0xedb, 0x6e8, 0xee7, 0xef9, 0x6f6, 0x690, 0xe9f, 0xe81, 0x68e, 0xebd, 0x6b2, 0x6ac, 0xea3,
-    0x660, 0xe6f, 0xe71, 0x67e, 0xe4d, 0x642, 0x65c, 0xe53, 0xe35, 0x63a, 0x624, 0xe2b, 0x618, 0xe17, 0xe09, 0x606
-};
-
-crc12_t crc_reflect(crc12_t data, size_t data_len)
-{
-	unsigned int i;
-	crc12_t ret = data & 0x01;
-
-	for (i = 1; i < data_len; i++)
-	{
-		data >>= 1;
-		ret = (ret << 1) | (data & 0x01);
-	}
-
-	return ret;
-}
+// This file is generated by generate_table in extconf.rb
+#include "crc12_3gpp_table.h"
 
 crc12_t crc12_3gpp_update(crc12_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc12_3gpp_table[15][d[ 0] ^ ((crc >>  4) & 0xff)] ^
+		      crc12_3gpp_table[14][d[ 1] ^ ((crc <<  4) & 0xff)] ^
+		      crc12_3gpp_table[13][d[ 2]                       ] ^
+		      crc12_3gpp_table[12][d[ 3]                       ] ^
+		      crc12_3gpp_table[11][d[ 4]                       ] ^
+		      crc12_3gpp_table[10][d[ 5]                       ] ^
+		      crc12_3gpp_table[ 9][d[ 6]                       ] ^
+		      crc12_3gpp_table[ 8][d[ 7]                       ] ^
+		      crc12_3gpp_table[ 7][d[ 8]                       ] ^
+		      crc12_3gpp_table[ 6][d[ 9]                       ] ^
+		      crc12_3gpp_table[ 5][d[10]                       ] ^
+		      crc12_3gpp_table[ 4][d[11]                       ] ^
+		      crc12_3gpp_table[ 3][d[12]                       ] ^
+		      crc12_3gpp_table[ 2][d[13]                       ] ^
+		      crc12_3gpp_table[ 1][d[14]                       ] ^
+		      crc12_3gpp_table[ 0][d[15]                       ];
+		crc &= 0xfff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 4) ^ *d) & 0xff;
-		crc = (crc12_table[tbl_idx] ^ (crc << 8)) & 0xfff;
+		crc = (crc12_3gpp_table[0][tbl_idx] ^ (crc << 8)) & 0xfff;
 		d++;
 	}
 
diff --git a/ext/digest/crc12_3gpp/extconf.rb b/ext/digest/crc12_3gpp/extconf.rb
index f940301..88df7d8 100644
--- a/ext/digest/crc12_3gpp/extconf.rb
+++ b/ext/digest/crc12_3gpp/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc12_3gpp_table.h", "crc12_3gpp_table", 12, 0x080f, false)
+
 create_header
 create_makefile "crc12_3gpp_ext"
diff --git a/ext/digest/crc15/crc15.c b/ext/digest/crc15/crc15.c
index 1c0ea11..7dd067c 100644
--- a/ext/digest/crc15/crc15.c
+++ b/ext/digest/crc15/crc15.c
@@ -15,38 +15,42 @@
  */
 
 #include "crc15.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc15_t crc15_table[256] = {
-    0x0000, 0x4599, 0x4eab, 0x0b32, 0x58cf, 0x1d56, 0x1664, 0x53fd, 0x7407, 0x319e, 0x3aac, 0x7f35, 0x2cc8, 0x6951, 0x6263, 0x27fa,
-    0x2d97, 0x680e, 0x633c, 0x26a5, 0x7558, 0x30c1, 0x3bf3, 0x7e6a, 0x5990, 0x1c09, 0x173b, 0x52a2, 0x015f, 0x44c6, 0x4ff4, 0x0a6d,
-    0x5b2e, 0x1eb7, 0x1585, 0x501c, 0x03e1, 0x4678, 0x4d4a, 0x08d3, 0x2f29, 0x6ab0, 0x6182, 0x241b, 0x77e6, 0x327f, 0x394d, 0x7cd4,
-    0x76b9, 0x3320, 0x3812, 0x7d8b, 0x2e76, 0x6bef, 0x60dd, 0x2544, 0x02be, 0x4727, 0x4c15, 0x098c, 0x5a71, 0x1fe8, 0x14da, 0x5143,
-    0x73c5, 0x365c, 0x3d6e, 0x78f7, 0x2b0a, 0x6e93, 0x65a1, 0x2038, 0x07c2, 0x425b, 0x4969, 0x0cf0, 0x5f0d, 0x1a94, 0x11a6, 0x543f,
-    0x5e52, 0x1bcb, 0x10f9, 0x5560, 0x069d, 0x4304, 0x4836, 0x0daf, 0x2a55, 0x6fcc, 0x64fe, 0x2167, 0x729a, 0x3703, 0x3c31, 0x79a8,
-    0x28eb, 0x6d72, 0x6640, 0x23d9, 0x7024, 0x35bd, 0x3e8f, 0x7b16, 0x5cec, 0x1975, 0x1247, 0x57de, 0x0423, 0x41ba, 0x4a88, 0x0f11,
-    0x057c, 0x40e5, 0x4bd7, 0x0e4e, 0x5db3, 0x182a, 0x1318, 0x5681, 0x717b, 0x34e2, 0x3fd0, 0x7a49, 0x29b4, 0x6c2d, 0x671f, 0x2286,
-    0x2213, 0x678a, 0x6cb8, 0x2921, 0x7adc, 0x3f45, 0x3477, 0x71ee, 0x5614, 0x138d, 0x18bf, 0x5d26, 0x0edb, 0x4b42, 0x4070, 0x05e9,
-    0x0f84, 0x4a1d, 0x412f, 0x04b6, 0x574b, 0x12d2, 0x19e0, 0x5c79, 0x7b83, 0x3e1a, 0x3528, 0x70b1, 0x234c, 0x66d5, 0x6de7, 0x287e,
-    0x793d, 0x3ca4, 0x3796, 0x720f, 0x21f2, 0x646b, 0x6f59, 0x2ac0, 0x0d3a, 0x48a3, 0x4391, 0x0608, 0x55f5, 0x106c, 0x1b5e, 0x5ec7,
-    0x54aa, 0x1133, 0x1a01, 0x5f98, 0x0c65, 0x49fc, 0x42ce, 0x0757, 0x20ad, 0x6534, 0x6e06, 0x2b9f, 0x7862, 0x3dfb, 0x36c9, 0x7350,
-    0x51d6, 0x144f, 0x1f7d, 0x5ae4, 0x0919, 0x4c80, 0x47b2, 0x022b, 0x25d1, 0x6048, 0x6b7a, 0x2ee3, 0x7d1e, 0x3887, 0x33b5, 0x762c,
-    0x7c41, 0x39d8, 0x32ea, 0x7773, 0x248e, 0x6117, 0x6a25, 0x2fbc, 0x0846, 0x4ddf, 0x46ed, 0x0374, 0x5089, 0x1510, 0x1e22, 0x5bbb,
-    0x0af8, 0x4f61, 0x4453, 0x01ca, 0x5237, 0x17ae, 0x1c9c, 0x5905, 0x7eff, 0x3b66, 0x3054, 0x75cd, 0x2630, 0x63a9, 0x689b, 0x2d02,
-    0x276f, 0x62f6, 0x69c4, 0x2c5d, 0x7fa0, 0x3a39, 0x310b, 0x7492, 0x5368, 0x16f1, 0x1dc3, 0x585a, 0x0ba7, 0x4e3e, 0x450c, 0x0095
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc15_table.h"
 
 crc15_t crc15_update(crc15_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc15_table[15][d[ 0] ^ ((crc >>  7) & 0xff)] ^
+		      crc15_table[14][d[ 1] ^ ((crc <<  1) & 0xff)] ^
+		      crc15_table[13][d[ 2]                       ] ^
+		      crc15_table[12][d[ 3]                       ] ^
+		      crc15_table[11][d[ 4]                       ] ^
+		      crc15_table[10][d[ 5]                       ] ^
+		      crc15_table[ 9][d[ 6]                       ] ^
+		      crc15_table[ 8][d[ 7]                       ] ^
+		      crc15_table[ 7][d[ 8]                       ] ^
+		      crc15_table[ 6][d[ 9]                       ] ^
+		      crc15_table[ 5][d[10]                       ] ^
+		      crc15_table[ 4][d[11]                       ] ^
+		      crc15_table[ 3][d[12]                       ] ^
+		      crc15_table[ 2][d[13]                       ] ^
+		      crc15_table[ 1][d[14]                       ] ^
+		      crc15_table[ 0][d[15]                       ];
+		crc &= 0x7fff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 7) ^ *d) & 0xff;
-		crc = (crc15_table[tbl_idx] ^ (crc << 8)) & 0x7fff;
+		crc = (crc15_table[0][tbl_idx] ^ (crc << 8)) & 0x7fff;
 		d++;
 	}
 
diff --git a/ext/digest/crc15/extconf.rb b/ext/digest/crc15/extconf.rb
index 3114fe0..b0a4eaa 100644
--- a/ext/digest/crc15/extconf.rb
+++ b/ext/digest/crc15/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc15_table.h", "crc15_table", 15, 0x4599, false)
+
 create_header
 create_makefile "crc15_ext"
diff --git a/ext/digest/crc16/crc16.c b/ext/digest/crc16/crc16.c
index 3378cca..8f2c196 100644
--- a/ext/digest/crc16/crc16.c
+++ b/ext/digest/crc16/crc16.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc16_table[256] = {
-	0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
-	0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,
-	0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,
-	0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,
-	0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
-	0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
-	0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
-	0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
-	0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
-	0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
-	0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
-	0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
-	0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
-	0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
-	0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
-	0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
-	0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
-	0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
-	0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
-	0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
-	0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
-	0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
-	0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
-	0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
-	0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
-	0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
-	0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
-	0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
-	0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
-	0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
-	0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
-	0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_table.h"
 
 crc16_t crc16_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_table[13][d[ 2]                       ] ^
+		      crc16_table[12][d[ 3]                       ] ^
+		      crc16_table[11][d[ 4]                       ] ^
+		      crc16_table[10][d[ 5]                       ] ^
+		      crc16_table[ 9][d[ 6]                       ] ^
+		      crc16_table[ 8][d[ 7]                       ] ^
+		      crc16_table[ 7][d[ 8]                       ] ^
+		      crc16_table[ 6][d[ 9]                       ] ^
+		      crc16_table[ 5][d[10]                       ] ^
+		      crc16_table[ 4][d[11]                       ] ^
+		      crc16_table[ 3][d[12]                       ] ^
+		      crc16_table[ 2][d[13]                       ] ^
+		      crc16_table[ 1][d[14]                       ] ^
+		      crc16_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc16_table[tbl_idx] ^ (crc >> 8)) & 0xffff;
+		crc = (crc16_table[0][tbl_idx] ^ (crc >> 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16/extconf.rb b/ext/digest/crc16/extconf.rb
index 602e58a..0e6b358 100644
--- a/ext/digest/crc16/extconf.rb
+++ b/ext/digest/crc16/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_table.h", "crc16_table", 16, 0x8005, true)
+
 create_header
 create_makefile "crc16_ext"
diff --git a/ext/digest/crc16_ccitt/crc16_ccitt.c b/ext/digest/crc16_ccitt/crc16_ccitt.c
index 3c245cc..40f2753 100644
--- a/ext/digest/crc16_ccitt/crc16_ccitt.c
+++ b/ext/digest/crc16_ccitt/crc16_ccitt.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_ccitt.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc16_ccitt_table[256] = {
-	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
-	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
-	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
-	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
-	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
-	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
-	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
-	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
-	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
-	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
-	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
-	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
-	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
-	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
-	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
-	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
-	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
-	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
-	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
-	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
-	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
-	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
-	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
-	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
-	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
-	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
-	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
-	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
-	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
-	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
-	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
-	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_ccitt_table.h"
 
 crc16_t crc16_ccitt_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_ccitt_table[15][d[ 0] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_ccitt_table[14][d[ 1] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_ccitt_table[13][d[ 2]                       ] ^
+		      crc16_ccitt_table[12][d[ 3]                       ] ^
+		      crc16_ccitt_table[11][d[ 4]                       ] ^
+		      crc16_ccitt_table[10][d[ 5]                       ] ^
+		      crc16_ccitt_table[ 9][d[ 6]                       ] ^
+		      crc16_ccitt_table[ 8][d[ 7]                       ] ^
+		      crc16_ccitt_table[ 7][d[ 8]                       ] ^
+		      crc16_ccitt_table[ 6][d[ 9]                       ] ^
+		      crc16_ccitt_table[ 5][d[10]                       ] ^
+		      crc16_ccitt_table[ 4][d[11]                       ] ^
+		      crc16_ccitt_table[ 3][d[12]                       ] ^
+		      crc16_ccitt_table[ 2][d[13]                       ] ^
+		      crc16_ccitt_table[ 1][d[14]                       ] ^
+		      crc16_ccitt_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 8) ^ *d) & 0xff;
-		crc = (crc16_ccitt_table[tbl_idx] ^ (crc << 8)) & 0xffff;
+		crc = (crc16_ccitt_table[0][tbl_idx] ^ (crc << 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_ccitt/extconf.rb b/ext/digest/crc16_ccitt/extconf.rb
index 7c21c2c..4cedec7 100644
--- a/ext/digest/crc16_ccitt/extconf.rb
+++ b/ext/digest/crc16_ccitt/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_ccitt_table.h", "crc16_ccitt_table", 16, 0x1021, false)
+
 create_header
 create_makefile "crc16_ccitt_ext"
diff --git a/ext/digest/crc16_dnp/crc16_dnp.c b/ext/digest/crc16_dnp/crc16_dnp.c
index 240e62c..cbc5ed3 100644
--- a/ext/digest/crc16_dnp/crc16_dnp.c
+++ b/ext/digest/crc16_dnp/crc16_dnp.c
@@ -1,52 +1,40 @@
 #include "crc16_dnp.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc16_dnp_table[256] = {
-	0x0000,  0x365e,  0x6cbc,  0x5ae2,  0xd978,  0xef26,  0xb5c4,  0x839a,
-	0xff89,  0xc9d7,  0x9335,  0xa56b,  0x26f1,  0x10af,  0x4a4d,  0x7c13,
-	0xb26b,  0x8435,  0xded7,  0xe889,  0x6b13,  0x5d4d,  0x07af,  0x31f1,
-	0x4de2,  0x7bbc,  0x215e,  0x1700,  0x949a,  0xa2c4,  0xf826,  0xce78,
-	0x29af,  0x1ff1,  0x4513,  0x734d,  0xf0d7,  0xc689,  0x9c6b,  0xaa35,
-	0xd626,  0xe078,  0xba9a,  0x8cc4,  0x0f5e,  0x3900,  0x63e2,  0x55bc,
-	0x9bc4,  0xad9a,  0xf778,  0xc126,  0x42bc,  0x74e2,  0x2e00,  0x185e,
-	0x644d,  0x5213,  0x08f1,  0x3eaf,  0xbd35,  0x8b6b,  0xd189,  0xe7d7,
-	0x535e,  0x6500,  0x3fe2,  0x09bc,  0x8a26,  0xbc78,  0xe69a,  0xd0c4,
-	0xacd7,  0x9a89,  0xc06b,  0xf635,  0x75af,  0x43f1,  0x1913,  0x2f4d,
-	0xe135,  0xd76b,  0x8d89,  0xbbd7,  0x384d,  0x0e13,  0x54f1,  0x62af,
-	0x1ebc,  0x28e2,  0x7200,  0x445e,  0xc7c4,  0xf19a,  0xab78,  0x9d26,
-	0x7af1,  0x4caf,  0x164d,  0x2013,  0xa389,  0x95d7,  0xcf35,  0xf96b,
-	0x8578,  0xb326,  0xe9c4,  0xdf9a,  0x5c00,  0x6a5e,  0x30bc,  0x06e2,
-	0xc89a,  0xfec4,  0xa426,  0x9278,  0x11e2,  0x27bc,  0x7d5e,  0x4b00,
-	0x3713,  0x014d,  0x5baf,  0x6df1,  0xee6b,  0xd835,  0x82d7,  0xb489,
-	0xa6bc,  0x90e2,  0xca00,  0xfc5e,  0x7fc4,  0x499a,  0x1378,  0x2526,
-	0x5935,  0x6f6b,  0x3589,  0x03d7,  0x804d,  0xb613,  0xecf1,  0xdaaf,
-	0x14d7,  0x2289,  0x786b,  0x4e35,  0xcdaf,  0xfbf1,  0xa113,  0x974d,
-	0xeb5e,  0xdd00,  0x87e2,  0xb1bc,  0x3226,  0x0478,  0x5e9a,  0x68c4,
-	0x8f13,  0xb94d,  0xe3af,  0xd5f1,  0x566b,  0x6035,  0x3ad7,  0x0c89,
-	0x709a,  0x46c4,  0x1c26,  0x2a78,  0xa9e2,  0x9fbc,  0xc55e,  0xf300,
-	0x3d78,  0x0b26,  0x51c4,  0x679a,  0xe400,  0xd25e,  0x88bc,  0xbee2,
-	0xc2f1,  0xf4af,  0xae4d,  0x9813,  0x1b89,  0x2dd7,  0x7735,  0x416b,
-	0xf5e2,  0xc3bc,  0x995e,  0xaf00,  0x2c9a,  0x1ac4,  0x4026,  0x7678,
-	0x0a6b,  0x3c35,  0x66d7,  0x5089,  0xd313,  0xe54d,  0xbfaf,  0x89f1,
-	0x4789,  0x71d7,  0x2b35,  0x1d6b,  0x9ef1,  0xa8af,  0xf24d,  0xc413,
-	0xb800,  0x8e5e,  0xd4bc,  0xe2e2,  0x6178,  0x5726,  0x0dc4,  0x3b9a,
-	0xdc4d,  0xea13,  0xb0f1,  0x86af,  0x0535,  0x336b,  0x6989,  0x5fd7,
-	0x23c4,  0x159a,  0x4f78,  0x7926,  0xfabc,  0xcce2,  0x9600,  0xa05e,
-	0x6e26,  0x5878,  0x029a,  0x34c4,  0xb75e,  0x8100,  0xdbe2,  0xedbc,
-	0x91af,  0xa7f1,  0xfd13,  0xcb4d,  0x48d7,  0x7e89,  0x246b,  0x1235
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_dnp_table.h"
 
 crc16_t crc16_dnp_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_dnp_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_dnp_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_dnp_table[13][d[ 2]                       ] ^
+		      crc16_dnp_table[12][d[ 3]                       ] ^
+		      crc16_dnp_table[11][d[ 4]                       ] ^
+		      crc16_dnp_table[10][d[ 5]                       ] ^
+		      crc16_dnp_table[ 9][d[ 6]                       ] ^
+		      crc16_dnp_table[ 8][d[ 7]                       ] ^
+		      crc16_dnp_table[ 7][d[ 8]                       ] ^
+		      crc16_dnp_table[ 6][d[ 9]                       ] ^
+		      crc16_dnp_table[ 5][d[10]                       ] ^
+		      crc16_dnp_table[ 4][d[11]                       ] ^
+		      crc16_dnp_table[ 3][d[12]                       ] ^
+		      crc16_dnp_table[ 2][d[13]                       ] ^
+		      crc16_dnp_table[ 1][d[14]                       ] ^
+		      crc16_dnp_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc << 8) ^ crc16_dnp_table[tbl_idx];
+		crc = (crc16_dnp_table[0][tbl_idx] ^ (crc >> 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_dnp/extconf.rb b/ext/digest/crc16_dnp/extconf.rb
index 8df65cb..4faf533 100644
--- a/ext/digest/crc16_dnp/extconf.rb
+++ b/ext/digest/crc16_dnp/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_dnp_table.h", "crc16_dnp_table", 16, 0x3d65, true)
+
 create_header
 create_makefile "crc16_dnp_ext"
diff --git a/ext/digest/crc16_genibus/crc16_genibus.c b/ext/digest/crc16_genibus/crc16_genibus.c
index 866a311..216b2a8 100644
--- a/ext/digest/crc16_genibus/crc16_genibus.c
+++ b/ext/digest/crc16_genibus/crc16_genibus.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_genibus.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc16_genibus_table[256] = {
-	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
-	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
-	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
-	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
-	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
-	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
-	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
-	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
-	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
-	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
-	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
-	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
-	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
-	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
-	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
-	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
-	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
-	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
-	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
-	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
-	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
-	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
-	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
-	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
-	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
-	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
-	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
-	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
-	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
-	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
-	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
-	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_genibus_table.h"
 
 crc16_t crc16_genibus_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_genibus_table[15][d[ 0] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_genibus_table[14][d[ 1] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_genibus_table[13][d[ 2]                       ] ^
+		      crc16_genibus_table[12][d[ 3]                       ] ^
+		      crc16_genibus_table[11][d[ 4]                       ] ^
+		      crc16_genibus_table[10][d[ 5]                       ] ^
+		      crc16_genibus_table[ 9][d[ 6]                       ] ^
+		      crc16_genibus_table[ 8][d[ 7]                       ] ^
+		      crc16_genibus_table[ 7][d[ 8]                       ] ^
+		      crc16_genibus_table[ 6][d[ 9]                       ] ^
+		      crc16_genibus_table[ 5][d[10]                       ] ^
+		      crc16_genibus_table[ 4][d[11]                       ] ^
+		      crc16_genibus_table[ 3][d[12]                       ] ^
+		      crc16_genibus_table[ 2][d[13]                       ] ^
+		      crc16_genibus_table[ 1][d[14]                       ] ^
+		      crc16_genibus_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 8) ^ *d) & 0xff;
-		crc = (crc16_genibus_table[tbl_idx] ^ (crc << 8)) & 0xffff;
+		crc = (crc16_genibus_table[0][tbl_idx] ^ (crc << 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_genibus/extconf.rb b/ext/digest/crc16_genibus/extconf.rb
index 627aaeb..16cf162 100644
--- a/ext/digest/crc16_genibus/extconf.rb
+++ b/ext/digest/crc16_genibus/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_genibus_table.h", "crc16_genibus_table", 16, 0x1021, false)
+
 create_header
 create_makefile "crc16_genibus_ext"
diff --git a/ext/digest/crc16_kermit/crc16_kermit.c b/ext/digest/crc16_kermit/crc16_kermit.c
index 2828671..95a5763 100644
--- a/ext/digest/crc16_kermit/crc16_kermit.c
+++ b/ext/digest/crc16_kermit/crc16_kermit.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_kermit.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc_table[256] = {
-	0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
-	0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
-	0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
-	0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
-	0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
-	0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
-	0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
-	0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
-	0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
-	0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
-	0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
-	0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
-	0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
-	0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
-	0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
-	0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
-	0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
-	0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
-	0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
-	0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
-	0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
-	0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
-	0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
-	0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
-	0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
-	0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
-	0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
-	0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
-	0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
-	0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
-	0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
-	0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_kermit_table.h"
 
 crc16_t crc16_kermit_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_kermit_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_kermit_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_kermit_table[13][d[ 2]                       ] ^
+		      crc16_kermit_table[12][d[ 3]                       ] ^
+		      crc16_kermit_table[11][d[ 4]                       ] ^
+		      crc16_kermit_table[10][d[ 5]                       ] ^
+		      crc16_kermit_table[ 9][d[ 6]                       ] ^
+		      crc16_kermit_table[ 8][d[ 7]                       ] ^
+		      crc16_kermit_table[ 7][d[ 8]                       ] ^
+		      crc16_kermit_table[ 6][d[ 9]                       ] ^
+		      crc16_kermit_table[ 5][d[10]                       ] ^
+		      crc16_kermit_table[ 4][d[11]                       ] ^
+		      crc16_kermit_table[ 3][d[12]                       ] ^
+		      crc16_kermit_table[ 2][d[13]                       ] ^
+		      crc16_kermit_table[ 1][d[14]                       ] ^
+		      crc16_kermit_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc_table[tbl_idx] ^ (crc >> 8)) & 0xffff;
+		crc = (crc16_kermit_table[0][tbl_idx] ^ (crc >> 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_kermit/extconf.rb b/ext/digest/crc16_kermit/extconf.rb
index 6d0f907..5898bea 100644
--- a/ext/digest/crc16_kermit/extconf.rb
+++ b/ext/digest/crc16_kermit/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_kermit_table.h", "crc16_kermit_table", 16, 0x1021, true)
+
 create_header
 create_makefile "crc16_kermit_ext"
diff --git a/ext/digest/crc16_modbus/crc16_modbus.c b/ext/digest/crc16_modbus/crc16_modbus.c
index 1830c59..1196137 100644
--- a/ext/digest/crc16_modbus/crc16_modbus.c
+++ b/ext/digest/crc16_modbus/crc16_modbus.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_modbus.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc_table[256] = {
-	0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
-	0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,
-	0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,
-	0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,
-	0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
-	0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
-	0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
-	0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
-	0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
-	0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
-	0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
-	0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
-	0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
-	0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
-	0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
-	0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
-	0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
-	0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
-	0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
-	0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
-	0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
-	0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
-	0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
-	0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
-	0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
-	0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
-	0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
-	0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
-	0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
-	0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
-	0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
-	0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_modbus_table.h"
 
 crc16_t crc16_modbus_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_modbus_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_modbus_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_modbus_table[13][d[ 2]                       ] ^
+		      crc16_modbus_table[12][d[ 3]                       ] ^
+		      crc16_modbus_table[11][d[ 4]                       ] ^
+		      crc16_modbus_table[10][d[ 5]                       ] ^
+		      crc16_modbus_table[ 9][d[ 6]                       ] ^
+		      crc16_modbus_table[ 8][d[ 7]                       ] ^
+		      crc16_modbus_table[ 7][d[ 8]                       ] ^
+		      crc16_modbus_table[ 6][d[ 9]                       ] ^
+		      crc16_modbus_table[ 5][d[10]                       ] ^
+		      crc16_modbus_table[ 4][d[11]                       ] ^
+		      crc16_modbus_table[ 3][d[12]                       ] ^
+		      crc16_modbus_table[ 2][d[13]                       ] ^
+		      crc16_modbus_table[ 1][d[14]                       ] ^
+		      crc16_modbus_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc_table[tbl_idx] ^ (crc >> 8)) & 0xffff;
+		crc = (crc16_modbus_table[0][tbl_idx] ^ (crc >> 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_modbus/extconf.rb b/ext/digest/crc16_modbus/extconf.rb
index 8373439..0fc53d0 100644
--- a/ext/digest/crc16_modbus/extconf.rb
+++ b/ext/digest/crc16_modbus/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_modbus_table.h", "crc16_modbus_table", 16, 0x8005, true)
+
 create_header
 create_makefile "crc16_modbus_ext"
diff --git a/ext/digest/crc16_usb/crc16_usb.c b/ext/digest/crc16_usb/crc16_usb.c
index b6561a8..776ba4e 100644
--- a/ext/digest/crc16_usb/crc16_usb.c
+++ b/ext/digest/crc16_usb/crc16_usb.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_usb.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc_table[256] = {
-	0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
-	0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,
-	0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,
-	0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,
-	0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
-	0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
-	0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
-	0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
-	0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
-	0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
-	0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
-	0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
-	0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
-	0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
-	0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
-	0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
-	0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
-	0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
-	0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
-	0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
-	0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
-	0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
-	0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
-	0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
-	0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
-	0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
-	0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
-	0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
-	0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
-	0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
-	0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
-	0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_usb_table.h"
 
 crc16_t crc16_usb_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_usb_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_usb_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_usb_table[13][d[ 2]                       ] ^
+		      crc16_usb_table[12][d[ 3]                       ] ^
+		      crc16_usb_table[11][d[ 4]                       ] ^
+		      crc16_usb_table[10][d[ 5]                       ] ^
+		      crc16_usb_table[ 9][d[ 6]                       ] ^
+		      crc16_usb_table[ 8][d[ 7]                       ] ^
+		      crc16_usb_table[ 7][d[ 8]                       ] ^
+		      crc16_usb_table[ 6][d[ 9]                       ] ^
+		      crc16_usb_table[ 5][d[10]                       ] ^
+		      crc16_usb_table[ 4][d[11]                       ] ^
+		      crc16_usb_table[ 3][d[12]                       ] ^
+		      crc16_usb_table[ 2][d[13]                       ] ^
+		      crc16_usb_table[ 1][d[14]                       ] ^
+		      crc16_usb_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc_table[tbl_idx] ^ (crc >> 8)) & 0xffff;
+		crc = (crc16_usb_table[0][tbl_idx] ^ (crc >> 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_usb/extconf.rb b/ext/digest/crc16_usb/extconf.rb
index 6aa74d0..6928eae 100644
--- a/ext/digest/crc16_usb/extconf.rb
+++ b/ext/digest/crc16_usb/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_usb_table.h", "crc16_usb_table", 16, 0x8005, true)
+
 create_header
 create_makefile "crc16_usb_ext"
diff --git a/ext/digest/crc16_x_25/crc16_x_25.c b/ext/digest/crc16_x_25/crc16_x_25.c
index 9c3b8bc..d69b650 100644
--- a/ext/digest/crc16_x_25/crc16_x_25.c
+++ b/ext/digest/crc16_x_25/crc16_x_25.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_x_25.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc_table[256] = {
-	0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
-	0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
-	0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
-	0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
-	0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
-	0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
-	0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
-	0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
-	0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
-	0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
-	0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
-	0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
-	0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
-	0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
-	0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
-	0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
-	0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
-	0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
-	0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
-	0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
-	0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
-	0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
-	0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
-	0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
-	0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
-	0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
-	0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
-	0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
-	0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
-	0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
-	0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
-	0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_x_25_table.h"
 
 crc16_t crc16_x_25_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_x_25_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_x_25_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_x_25_table[13][d[ 2]                       ] ^
+		      crc16_x_25_table[12][d[ 3]                       ] ^
+		      crc16_x_25_table[11][d[ 4]                       ] ^
+		      crc16_x_25_table[10][d[ 5]                       ] ^
+		      crc16_x_25_table[ 9][d[ 6]                       ] ^
+		      crc16_x_25_table[ 8][d[ 7]                       ] ^
+		      crc16_x_25_table[ 7][d[ 8]                       ] ^
+		      crc16_x_25_table[ 6][d[ 9]                       ] ^
+		      crc16_x_25_table[ 5][d[10]                       ] ^
+		      crc16_x_25_table[ 4][d[11]                       ] ^
+		      crc16_x_25_table[ 3][d[12]                       ] ^
+		      crc16_x_25_table[ 2][d[13]                       ] ^
+		      crc16_x_25_table[ 1][d[14]                       ] ^
+		      crc16_x_25_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc_table[tbl_idx] ^ (crc >> 8)) & 0xffff;
+		crc = (crc16_x_25_table[0][tbl_idx] ^ (crc >> 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_x_25/extconf.rb b/ext/digest/crc16_x_25/extconf.rb
index 4f775db..5d9ed55 100644
--- a/ext/digest/crc16_x_25/extconf.rb
+++ b/ext/digest/crc16_x_25/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_x_25_table.h", "crc16_x_25_table", 16, 0x1021, true)
+
 create_header
 create_makefile "crc16_x_25_ext"
diff --git a/ext/digest/crc16_xmodem/crc16_xmodem.c b/ext/digest/crc16_xmodem/crc16_xmodem.c
index f797a10..9be1019 100644
--- a/ext/digest/crc16_xmodem/crc16_xmodem.c
+++ b/ext/digest/crc16_xmodem/crc16_xmodem.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_xmodem.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc16_xmodem_table[256] = {
-	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
-	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
-	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
-	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
-	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
-	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
-	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
-	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
-	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
-	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
-	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
-	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
-	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
-	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
-	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
-	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
-	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
-	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
-	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
-	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
-	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
-	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
-	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
-	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
-	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
-	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
-	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
-	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
-	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
-	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
-	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
-	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_xmodem_table.h"
 
 crc16_t crc16_xmodem_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_xmodem_table[15][d[ 0] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_xmodem_table[14][d[ 1] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_xmodem_table[13][d[ 2]                       ] ^
+		      crc16_xmodem_table[12][d[ 3]                       ] ^
+		      crc16_xmodem_table[11][d[ 4]                       ] ^
+		      crc16_xmodem_table[10][d[ 5]                       ] ^
+		      crc16_xmodem_table[ 9][d[ 6]                       ] ^
+		      crc16_xmodem_table[ 8][d[ 7]                       ] ^
+		      crc16_xmodem_table[ 7][d[ 8]                       ] ^
+		      crc16_xmodem_table[ 6][d[ 9]                       ] ^
+		      crc16_xmodem_table[ 5][d[10]                       ] ^
+		      crc16_xmodem_table[ 4][d[11]                       ] ^
+		      crc16_xmodem_table[ 3][d[12]                       ] ^
+		      crc16_xmodem_table[ 2][d[13]                       ] ^
+		      crc16_xmodem_table[ 1][d[14]                       ] ^
+		      crc16_xmodem_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 8) ^ *d) & 0xff;
-		crc = (crc16_xmodem_table[tbl_idx] ^ (crc << 8)) & 0xffff;
+		crc = (crc16_xmodem_table[0][tbl_idx] ^ (crc << 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_xmodem/extconf.rb b/ext/digest/crc16_xmodem/extconf.rb
index c290c5b..6551eaf 100644
--- a/ext/digest/crc16_xmodem/extconf.rb
+++ b/ext/digest/crc16_xmodem/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_xmodem_table.h", "crc16_xmodem_table", 16, 0x1021, false)
+
 create_header
 create_makefile "crc16_xmodem_ext"
diff --git a/ext/digest/crc16_zmodem/crc16_zmodem.c b/ext/digest/crc16_zmodem/crc16_zmodem.c
index 45c364b..1212669 100644
--- a/ext/digest/crc16_zmodem/crc16_zmodem.c
+++ b/ext/digest/crc16_zmodem/crc16_zmodem.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc16_zmodem.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc16_t crc16_zmodem_table[256] = {
-	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
-	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
-	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
-	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
-	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
-	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
-	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
-	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
-	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
-	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
-	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
-	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
-	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
-	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
-	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
-	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
-	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
-	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
-	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
-	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
-	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
-	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
-	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
-	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
-	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
-	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
-	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
-	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
-	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
-	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
-	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
-	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc16_zmodem_table.h"
 
 crc16_t crc16_zmodem_update(crc16_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc16_zmodem_table[15][d[ 0] ^ ((crc >>  8) & 0xff)] ^
+		      crc16_zmodem_table[14][d[ 1] ^ ((crc >>  0) & 0xff)] ^
+		      crc16_zmodem_table[13][d[ 2]                       ] ^
+		      crc16_zmodem_table[12][d[ 3]                       ] ^
+		      crc16_zmodem_table[11][d[ 4]                       ] ^
+		      crc16_zmodem_table[10][d[ 5]                       ] ^
+		      crc16_zmodem_table[ 9][d[ 6]                       ] ^
+		      crc16_zmodem_table[ 8][d[ 7]                       ] ^
+		      crc16_zmodem_table[ 7][d[ 8]                       ] ^
+		      crc16_zmodem_table[ 6][d[ 9]                       ] ^
+		      crc16_zmodem_table[ 5][d[10]                       ] ^
+		      crc16_zmodem_table[ 4][d[11]                       ] ^
+		      crc16_zmodem_table[ 3][d[12]                       ] ^
+		      crc16_zmodem_table[ 2][d[13]                       ] ^
+		      crc16_zmodem_table[ 1][d[14]                       ] ^
+		      crc16_zmodem_table[ 0][d[15]                       ];
+		crc &= 0xffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 8) ^ *d) & 0xff;
-		crc = (crc16_zmodem_table[tbl_idx] ^ (crc << 8)) & 0xffff;
+		crc = (crc16_zmodem_table[0][tbl_idx] ^ (crc << 8)) & 0xffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc16_zmodem/extconf.rb b/ext/digest/crc16_zmodem/extconf.rb
index bc2e4fa..4146dd8 100644
--- a/ext/digest/crc16_zmodem/extconf.rb
+++ b/ext/digest/crc16_zmodem/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc16_zmodem_table.h", "crc16_zmodem_table", 16, 0x1021, false)
+
 create_header
 create_makefile "crc16_zmodem_ext"
diff --git a/ext/digest/crc24/crc24.c b/ext/digest/crc24/crc24.c
index 6c1c44e..91e6587 100644
--- a/ext/digest/crc24/crc24.c
+++ b/ext/digest/crc24/crc24.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc24.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc24_t crc24_table[256] = {
-	0x000000, 0x864cfb, 0x8ad50d, 0x0c99f6, 0x93e6e1, 0x15aa1a, 0x1933ec, 0x9f7f17,
-	0xa18139, 0x27cdc2, 0x2b5434, 0xad18cf, 0x3267d8, 0xb42b23, 0xb8b2d5, 0x3efe2e,
-	0xc54e89, 0x430272, 0x4f9b84, 0xc9d77f, 0x56a868, 0xd0e493, 0xdc7d65, 0x5a319e,
-	0x64cfb0, 0xe2834b, 0xee1abd, 0x685646, 0xf72951, 0x7165aa, 0x7dfc5c, 0xfbb0a7,
-	0x0cd1e9, 0x8a9d12, 0x8604e4, 0x00481f, 0x9f3708, 0x197bf3, 0x15e205, 0x93aefe,
-	0xad50d0, 0x2b1c2b, 0x2785dd, 0xa1c926, 0x3eb631, 0xb8faca, 0xb4633c, 0x322fc7,
-	0xc99f60, 0x4fd39b, 0x434a6d, 0xc50696, 0x5a7981, 0xdc357a, 0xd0ac8c, 0x56e077,
-	0x681e59, 0xee52a2, 0xe2cb54, 0x6487af, 0xfbf8b8, 0x7db443, 0x712db5, 0xf7614e,
-	0x19a3d2, 0x9fef29, 0x9376df, 0x153a24, 0x8a4533, 0x0c09c8, 0x00903e, 0x86dcc5,
-	0xb822eb, 0x3e6e10, 0x32f7e6, 0xb4bb1d, 0x2bc40a, 0xad88f1, 0xa11107, 0x275dfc,
-	0xdced5b, 0x5aa1a0, 0x563856, 0xd074ad, 0x4f0bba, 0xc94741, 0xc5deb7, 0x43924c,
-	0x7d6c62, 0xfb2099, 0xf7b96f, 0x71f594, 0xee8a83, 0x68c678, 0x645f8e, 0xe21375,
-	0x15723b, 0x933ec0, 0x9fa736, 0x19ebcd, 0x8694da, 0x00d821, 0x0c41d7, 0x8a0d2c,
-	0xb4f302, 0x32bff9, 0x3e260f, 0xb86af4, 0x2715e3, 0xa15918, 0xadc0ee, 0x2b8c15,
-	0xd03cb2, 0x567049, 0x5ae9bf, 0xdca544, 0x43da53, 0xc596a8, 0xc90f5e, 0x4f43a5,
-	0x71bd8b, 0xf7f170, 0xfb6886, 0x7d247d, 0xe25b6a, 0x641791, 0x688e67, 0xeec29c,
-	0x3347a4, 0xb50b5f, 0xb992a9, 0x3fde52, 0xa0a145, 0x26edbe, 0x2a7448, 0xac38b3,
-	0x92c69d, 0x148a66, 0x181390, 0x9e5f6b, 0x01207c, 0x876c87, 0x8bf571, 0x0db98a,
-	0xf6092d, 0x7045d6, 0x7cdc20, 0xfa90db, 0x65efcc, 0xe3a337, 0xef3ac1, 0x69763a,
-	0x578814, 0xd1c4ef, 0xdd5d19, 0x5b11e2, 0xc46ef5, 0x42220e, 0x4ebbf8, 0xc8f703,
-	0x3f964d, 0xb9dab6, 0xb54340, 0x330fbb, 0xac70ac, 0x2a3c57, 0x26a5a1, 0xa0e95a,
-	0x9e1774, 0x185b8f, 0x14c279, 0x928e82, 0x0df195, 0x8bbd6e, 0x872498, 0x016863,
-	0xfad8c4, 0x7c943f, 0x700dc9, 0xf64132, 0x693e25, 0xef72de, 0xe3eb28, 0x65a7d3,
-	0x5b59fd, 0xdd1506, 0xd18cf0, 0x57c00b, 0xc8bf1c, 0x4ef3e7, 0x426a11, 0xc426ea,
-	0x2ae476, 0xaca88d, 0xa0317b, 0x267d80, 0xb90297, 0x3f4e6c, 0x33d79a, 0xb59b61,
-	0x8b654f, 0x0d29b4, 0x01b042, 0x87fcb9, 0x1883ae, 0x9ecf55, 0x9256a3, 0x141a58,
-	0xefaaff, 0x69e604, 0x657ff2, 0xe33309, 0x7c4c1e, 0xfa00e5, 0xf69913, 0x70d5e8,
-	0x4e2bc6, 0xc8673d, 0xc4fecb, 0x42b230, 0xddcd27, 0x5b81dc, 0x57182a, 0xd154d1,
-	0x26359f, 0xa07964, 0xace092, 0x2aac69, 0xb5d37e, 0x339f85, 0x3f0673, 0xb94a88,
-	0x87b4a6, 0x01f85d, 0x0d61ab, 0x8b2d50, 0x145247, 0x921ebc, 0x9e874a, 0x18cbb1,
-	0xe37b16, 0x6537ed, 0x69ae1b, 0xefe2e0, 0x709df7, 0xf6d10c, 0xfa48fa, 0x7c0401,
-	0x42fa2f, 0xc4b6d4, 0xc82f22, 0x4e63d9, 0xd11cce, 0x575035, 0x5bc9c3, 0xdd8538
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc24_table.h"
 
 crc24_t crc24_update(crc24_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc24_table[15][d[ 0] ^ ((crc >> 16) & 0xff)] ^
+		      crc24_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc24_table[13][d[ 2] ^ ((crc >>  0) & 0xff)] ^
+		      crc24_table[12][d[ 3]                       ] ^
+		      crc24_table[11][d[ 4]                       ] ^
+		      crc24_table[10][d[ 5]                       ] ^
+		      crc24_table[ 9][d[ 6]                       ] ^
+		      crc24_table[ 8][d[ 7]                       ] ^
+		      crc24_table[ 7][d[ 8]                       ] ^
+		      crc24_table[ 6][d[ 9]                       ] ^
+		      crc24_table[ 5][d[10]                       ] ^
+		      crc24_table[ 4][d[11]                       ] ^
+		      crc24_table[ 3][d[12]                       ] ^
+		      crc24_table[ 2][d[13]                       ] ^
+		      crc24_table[ 1][d[14]                       ] ^
+		      crc24_table[ 0][d[15]                       ];
+		crc &= 0xffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 16) ^ *d) & 0xff;
-		crc = (crc24_table[tbl_idx] ^ (crc << 8)) & 0xffffff;
+		crc = (crc24_table[0][tbl_idx] ^ (crc << 8)) & 0xffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc24/extconf.rb b/ext/digest/crc24/extconf.rb
index 925d555..bbf34b8 100644
--- a/ext/digest/crc24/extconf.rb
+++ b/ext/digest/crc24/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc24_table.h", "crc24_table", 24, 0x00864cfb, false)
+
 create_header
 create_makefile "crc24_ext"
diff --git a/ext/digest/crc32/crc32.c b/ext/digest/crc32/crc32.c
index be9a49d..9279f42 100644
--- a/ext/digest/crc32/crc32.c
+++ b/ext/digest/crc32/crc32.c
@@ -14,54 +14,42 @@
  *  - Algorithm     = table-driven
  */
 #include "crc32.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32_table[256] = {
-	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
-	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
-	0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
-	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
-	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
-	0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
-	0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
-	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
-	0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
-	0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
-	0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
-	0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
-	0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
-	0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
-	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
-	0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
-	0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
-	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
-	0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
-	0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
-	0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
-	0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32_table.h"
 
 crc32_t crc32_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc32_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc32_table[13][d[ 2] ^ ((crc >> 16) & 0xff)] ^
+		      crc32_table[12][d[ 3] ^ ((crc >> 24) & 0xff)] ^
+		      crc32_table[11][d[ 4]                       ] ^
+		      crc32_table[10][d[ 5]                       ] ^
+		      crc32_table[ 9][d[ 6]                       ] ^
+		      crc32_table[ 8][d[ 7]                       ] ^
+		      crc32_table[ 7][d[ 8]                       ] ^
+		      crc32_table[ 6][d[ 9]                       ] ^
+		      crc32_table[ 5][d[10]                       ] ^
+		      crc32_table[ 4][d[11]                       ] ^
+		      crc32_table[ 3][d[12]                       ] ^
+		      crc32_table[ 2][d[13]                       ] ^
+		      crc32_table[ 1][d[14]                       ] ^
+		      crc32_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc32_table[tbl_idx] ^ (crc >> 8)) & 0xffffffff;
+		crc = (crc32_table[0][tbl_idx] ^ (crc >> 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32/extconf.rb b/ext/digest/crc32/extconf.rb
index 0b2138b..5291c47 100644
--- a/ext/digest/crc32/extconf.rb
+++ b/ext/digest/crc32/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32_table.h", "crc32_table", 32, 0x04c11db7, true)
+
 create_header
 create_makefile "crc32_ext"
diff --git a/ext/digest/crc32_bzip2/crc32_bzip2.c b/ext/digest/crc32_bzip2/crc32_bzip2.c
index d8b09da..8b7055c 100644
--- a/ext/digest/crc32_bzip2/crc32_bzip2.c
+++ b/ext/digest/crc32_bzip2/crc32_bzip2.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc32_bzip2.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32_bzip2_table[256] = {
-	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
-	0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
-	0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
-	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
-	0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
-	0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
-	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
-	0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
-	0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
-	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
-	0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
-	0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
-	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
-	0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
-	0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
-	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
-	0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
-	0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
-	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
-	0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
-	0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
-	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
-	0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
-	0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
-	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
-	0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
-	0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
-	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
-	0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
-	0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
-	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
-	0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32_bzip2_table.h"
 
 crc32_t crc32_bzip2_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32_bzip2_table[15][d[ 0] ^ ((crc >> 24) & 0xff)] ^
+		      crc32_bzip2_table[14][d[ 1] ^ ((crc >> 16) & 0xff)] ^
+		      crc32_bzip2_table[13][d[ 2] ^ ((crc >>  8) & 0xff)] ^
+		      crc32_bzip2_table[12][d[ 3] ^ ((crc >>  0) & 0xff)] ^
+		      crc32_bzip2_table[11][d[ 4]                       ] ^
+		      crc32_bzip2_table[10][d[ 5]                       ] ^
+		      crc32_bzip2_table[ 9][d[ 6]                       ] ^
+		      crc32_bzip2_table[ 8][d[ 7]                       ] ^
+		      crc32_bzip2_table[ 7][d[ 8]                       ] ^
+		      crc32_bzip2_table[ 6][d[ 9]                       ] ^
+		      crc32_bzip2_table[ 5][d[10]                       ] ^
+		      crc32_bzip2_table[ 4][d[11]                       ] ^
+		      crc32_bzip2_table[ 3][d[12]                       ] ^
+		      crc32_bzip2_table[ 2][d[13]                       ] ^
+		      crc32_bzip2_table[ 1][d[14]                       ] ^
+		      crc32_bzip2_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 24) ^ *d) & 0xff;
-		crc = (crc32_bzip2_table[tbl_idx] ^ (crc << 8)) & 0xffffffff;
+		crc = (crc32_bzip2_table[0][tbl_idx] ^ (crc << 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32_bzip2/extconf.rb b/ext/digest/crc32_bzip2/extconf.rb
index c6c47f1..edc45d9 100644
--- a/ext/digest/crc32_bzip2/extconf.rb
+++ b/ext/digest/crc32_bzip2/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32_bzip2_table.h", "crc32_bzip2_table", 32, 0x04c11db7, false)
+
 create_header
 create_makefile "crc32_bzip2_ext"
diff --git a/ext/digest/crc32_jam/crc32_jam.c b/ext/digest/crc32_jam/crc32_jam.c
index f5cd76a..e20beee 100644
--- a/ext/digest/crc32_jam/crc32_jam.c
+++ b/ext/digest/crc32_jam/crc32_jam.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc32_jam.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32_table[256] = {
-	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
-	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
-	0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
-	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
-	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
-	0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
-	0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
-	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
-	0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
-	0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
-	0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
-	0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
-	0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
-	0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
-	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
-	0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
-	0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
-	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
-	0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
-	0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
-	0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
-	0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32_jam_table.h"
 
 crc32_t crc32_jam_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32_jam_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc32_jam_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc32_jam_table[13][d[ 2] ^ ((crc >> 16) & 0xff)] ^
+		      crc32_jam_table[12][d[ 3] ^ ((crc >> 24) & 0xff)] ^
+		      crc32_jam_table[11][d[ 4]                       ] ^
+		      crc32_jam_table[10][d[ 5]                       ] ^
+		      crc32_jam_table[ 9][d[ 6]                       ] ^
+		      crc32_jam_table[ 8][d[ 7]                       ] ^
+		      crc32_jam_table[ 7][d[ 8]                       ] ^
+		      crc32_jam_table[ 6][d[ 9]                       ] ^
+		      crc32_jam_table[ 5][d[10]                       ] ^
+		      crc32_jam_table[ 4][d[11]                       ] ^
+		      crc32_jam_table[ 3][d[12]                       ] ^
+		      crc32_jam_table[ 2][d[13]                       ] ^
+		      crc32_jam_table[ 1][d[14]                       ] ^
+		      crc32_jam_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc32_table[tbl_idx] ^ (crc >> 8)) & 0xffffffff;
+		crc = (crc32_jam_table[0][tbl_idx] ^ (crc >> 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32_jam/extconf.rb b/ext/digest/crc32_jam/extconf.rb
index 2ad560d..f6c60a4 100644
--- a/ext/digest/crc32_jam/extconf.rb
+++ b/ext/digest/crc32_jam/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32_jam_table.h", "crc32_jam_table", 32, 0x04c11db7, true)
+
 create_header
 create_makefile "crc32_jam_ext"
diff --git a/ext/digest/crc32_mpeg/crc32_mpeg.c b/ext/digest/crc32_mpeg/crc32_mpeg.c
index 77ec2ea..d30785f 100644
--- a/ext/digest/crc32_mpeg/crc32_mpeg.c
+++ b/ext/digest/crc32_mpeg/crc32_mpeg.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc32_mpeg.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32_mpeg_table[256] = {
-	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
-	0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
-	0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
-	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
-	0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
-	0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
-	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
-	0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
-	0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
-	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
-	0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
-	0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
-	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
-	0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
-	0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
-	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
-	0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
-	0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
-	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
-	0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
-	0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
-	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
-	0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
-	0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
-	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
-	0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
-	0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
-	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
-	0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
-	0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
-	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
-	0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32_mpeg_table.h"
 
 crc32_t crc32_mpeg_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32_mpeg_table[15][d[ 0] ^ ((crc >> 24) & 0xff)] ^
+		      crc32_mpeg_table[14][d[ 1] ^ ((crc >> 16) & 0xff)] ^
+		      crc32_mpeg_table[13][d[ 2] ^ ((crc >>  8) & 0xff)] ^
+		      crc32_mpeg_table[12][d[ 3] ^ ((crc >>  0) & 0xff)] ^
+		      crc32_mpeg_table[11][d[ 4]                       ] ^
+		      crc32_mpeg_table[10][d[ 5]                       ] ^
+		      crc32_mpeg_table[ 9][d[ 6]                       ] ^
+		      crc32_mpeg_table[ 8][d[ 7]                       ] ^
+		      crc32_mpeg_table[ 7][d[ 8]                       ] ^
+		      crc32_mpeg_table[ 6][d[ 9]                       ] ^
+		      crc32_mpeg_table[ 5][d[10]                       ] ^
+		      crc32_mpeg_table[ 4][d[11]                       ] ^
+		      crc32_mpeg_table[ 3][d[12]                       ] ^
+		      crc32_mpeg_table[ 2][d[13]                       ] ^
+		      crc32_mpeg_table[ 1][d[14]                       ] ^
+		      crc32_mpeg_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 24) ^ *d) & 0xff;
-		crc = (crc32_mpeg_table[tbl_idx] ^ (crc << 8)) & 0xffffffff;
+		crc = (crc32_mpeg_table[0][tbl_idx] ^ (crc << 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32_mpeg/extconf.rb b/ext/digest/crc32_mpeg/extconf.rb
index a65e0bb..bb420f1 100644
--- a/ext/digest/crc32_mpeg/extconf.rb
+++ b/ext/digest/crc32_mpeg/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32_mpeg_table.h", "crc32_mpeg_table", 32, 0x04c11db7, false)
+
 create_header
 create_makefile "crc32_mpeg_ext"
diff --git a/ext/digest/crc32_posix/crc32_posix.c b/ext/digest/crc32_posix/crc32_posix.c
index 1ede671..105204e 100644
--- a/ext/digest/crc32_posix/crc32_posix.c
+++ b/ext/digest/crc32_posix/crc32_posix.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc32_posix.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32_posix_table[256] = {
-	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
-	0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
-	0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
-	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
-	0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
-	0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
-	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
-	0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
-	0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
-	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
-	0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
-	0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
-	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
-	0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
-	0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
-	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
-	0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
-	0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
-	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
-	0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
-	0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
-	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
-	0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
-	0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
-	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
-	0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
-	0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
-	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
-	0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
-	0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
-	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
-	0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32_posix_table.h"
 
 crc32_t crc32_posix_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32_posix_table[15][d[ 0] ^ ((crc >> 24) & 0xff)] ^
+		      crc32_posix_table[14][d[ 1] ^ ((crc >> 16) & 0xff)] ^
+		      crc32_posix_table[13][d[ 2] ^ ((crc >>  8) & 0xff)] ^
+		      crc32_posix_table[12][d[ 3] ^ ((crc >>  0) & 0xff)] ^
+		      crc32_posix_table[11][d[ 4]                       ] ^
+		      crc32_posix_table[10][d[ 5]                       ] ^
+		      crc32_posix_table[ 9][d[ 6]                       ] ^
+		      crc32_posix_table[ 8][d[ 7]                       ] ^
+		      crc32_posix_table[ 7][d[ 8]                       ] ^
+		      crc32_posix_table[ 6][d[ 9]                       ] ^
+		      crc32_posix_table[ 5][d[10]                       ] ^
+		      crc32_posix_table[ 4][d[11]                       ] ^
+		      crc32_posix_table[ 3][d[12]                       ] ^
+		      crc32_posix_table[ 2][d[13]                       ] ^
+		      crc32_posix_table[ 1][d[14]                       ] ^
+		      crc32_posix_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 24) ^ *d) & 0xff;
-		crc = (crc32_posix_table[tbl_idx] ^ (crc << 8)) & 0xffffffff;
+		crc = (crc32_posix_table[0][tbl_idx] ^ (crc << 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32_posix/extconf.rb b/ext/digest/crc32_posix/extconf.rb
index fb3c2a9..356d36b 100644
--- a/ext/digest/crc32_posix/extconf.rb
+++ b/ext/digest/crc32_posix/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32_posix_table.h", "crc32_posix_table", 32, 0x04c11db7, false)
+
 create_header
 create_makefile "crc32_posix_ext"
diff --git a/ext/digest/crc32_xfer/crc32_xfer.c b/ext/digest/crc32_xfer/crc32_xfer.c
index 141ee42..46aeb22 100644
--- a/ext/digest/crc32_xfer/crc32_xfer.c
+++ b/ext/digest/crc32_xfer/crc32_xfer.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc32_xfer.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32_xfer_table[256] = {
-	0x00000000, 0x000000af, 0x0000015e, 0x000001f1, 0x000002bc, 0x00000213, 0x000003e2, 0x0000034d,
-	0x00000578, 0x000005d7, 0x00000426, 0x00000489, 0x000007c4, 0x0000076b, 0x0000069a, 0x00000635,
-	0x00000af0, 0x00000a5f, 0x00000bae, 0x00000b01, 0x0000084c, 0x000008e3, 0x00000912, 0x000009bd,
-	0x00000f88, 0x00000f27, 0x00000ed6, 0x00000e79, 0x00000d34, 0x00000d9b, 0x00000c6a, 0x00000cc5,
-	0x000015e0, 0x0000154f, 0x000014be, 0x00001411, 0x0000175c, 0x000017f3, 0x00001602, 0x000016ad,
-	0x00001098, 0x00001037, 0x000011c6, 0x00001169, 0x00001224, 0x0000128b, 0x0000137a, 0x000013d5,
-	0x00001f10, 0x00001fbf, 0x00001e4e, 0x00001ee1, 0x00001dac, 0x00001d03, 0x00001cf2, 0x00001c5d,
-	0x00001a68, 0x00001ac7, 0x00001b36, 0x00001b99, 0x000018d4, 0x0000187b, 0x0000198a, 0x00001925,
-	0x00002bc0, 0x00002b6f, 0x00002a9e, 0x00002a31, 0x0000297c, 0x000029d3, 0x00002822, 0x0000288d,
-	0x00002eb8, 0x00002e17, 0x00002fe6, 0x00002f49, 0x00002c04, 0x00002cab, 0x00002d5a, 0x00002df5,
-	0x00002130, 0x0000219f, 0x0000206e, 0x000020c1, 0x0000238c, 0x00002323, 0x000022d2, 0x0000227d,
-	0x00002448, 0x000024e7, 0x00002516, 0x000025b9, 0x000026f4, 0x0000265b, 0x000027aa, 0x00002705,
-	0x00003e20, 0x00003e8f, 0x00003f7e, 0x00003fd1, 0x00003c9c, 0x00003c33, 0x00003dc2, 0x00003d6d,
-	0x00003b58, 0x00003bf7, 0x00003a06, 0x00003aa9, 0x000039e4, 0x0000394b, 0x000038ba, 0x00003815,
-	0x000034d0, 0x0000347f, 0x0000358e, 0x00003521, 0x0000366c, 0x000036c3, 0x00003732, 0x0000379d,
-	0x000031a8, 0x00003107, 0x000030f6, 0x00003059, 0x00003314, 0x000033bb, 0x0000324a, 0x000032e5,
-	0x00005780, 0x0000572f, 0x000056de, 0x00005671, 0x0000553c, 0x00005593, 0x00005462, 0x000054cd,
-	0x000052f8, 0x00005257, 0x000053a6, 0x00005309, 0x00005044, 0x000050eb, 0x0000511a, 0x000051b5,
-	0x00005d70, 0x00005ddf, 0x00005c2e, 0x00005c81, 0x00005fcc, 0x00005f63, 0x00005e92, 0x00005e3d,
-	0x00005808, 0x000058a7, 0x00005956, 0x000059f9, 0x00005ab4, 0x00005a1b, 0x00005bea, 0x00005b45,
-	0x00004260, 0x000042cf, 0x0000433e, 0x00004391, 0x000040dc, 0x00004073, 0x00004182, 0x0000412d,
-	0x00004718, 0x000047b7, 0x00004646, 0x000046e9, 0x000045a4, 0x0000450b, 0x000044fa, 0x00004455,
-	0x00004890, 0x0000483f, 0x000049ce, 0x00004961, 0x00004a2c, 0x00004a83, 0x00004b72, 0x00004bdd,
-	0x00004de8, 0x00004d47, 0x00004cb6, 0x00004c19, 0x00004f54, 0x00004ffb, 0x00004e0a, 0x00004ea5,
-	0x00007c40, 0x00007cef, 0x00007d1e, 0x00007db1, 0x00007efc, 0x00007e53, 0x00007fa2, 0x00007f0d,
-	0x00007938, 0x00007997, 0x00007866, 0x000078c9, 0x00007b84, 0x00007b2b, 0x00007ada, 0x00007a75,
-	0x000076b0, 0x0000761f, 0x000077ee, 0x00007741, 0x0000740c, 0x000074a3, 0x00007552, 0x000075fd,
-	0x000073c8, 0x00007367, 0x00007296, 0x00007239, 0x00007174, 0x000071db, 0x0000702a, 0x00007085,
-	0x000069a0, 0x0000690f, 0x000068fe, 0x00006851, 0x00006b1c, 0x00006bb3, 0x00006a42, 0x00006aed,
-	0x00006cd8, 0x00006c77, 0x00006d86, 0x00006d29, 0x00006e64, 0x00006ecb, 0x00006f3a, 0x00006f95,
-	0x00006350, 0x000063ff, 0x0000620e, 0x000062a1, 0x000061ec, 0x00006143, 0x000060b2, 0x0000601d,
-	0x00006628, 0x00006687, 0x00006776, 0x000067d9, 0x00006494, 0x0000643b, 0x000065ca, 0x00006565
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32_xfer_table.h"
 
 crc32_t crc32_xfer_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32_xfer_table[15][d[ 0] ^ ((crc >> 24) & 0xff)] ^
+		      crc32_xfer_table[14][d[ 1] ^ ((crc >> 16) & 0xff)] ^
+		      crc32_xfer_table[13][d[ 2] ^ ((crc >>  8) & 0xff)] ^
+		      crc32_xfer_table[12][d[ 3] ^ ((crc >>  0) & 0xff)] ^
+		      crc32_xfer_table[11][d[ 4]                       ] ^
+		      crc32_xfer_table[10][d[ 5]                       ] ^
+		      crc32_xfer_table[ 9][d[ 6]                       ] ^
+		      crc32_xfer_table[ 8][d[ 7]                       ] ^
+		      crc32_xfer_table[ 7][d[ 8]                       ] ^
+		      crc32_xfer_table[ 6][d[ 9]                       ] ^
+		      crc32_xfer_table[ 5][d[10]                       ] ^
+		      crc32_xfer_table[ 4][d[11]                       ] ^
+		      crc32_xfer_table[ 3][d[12]                       ] ^
+		      crc32_xfer_table[ 2][d[13]                       ] ^
+		      crc32_xfer_table[ 1][d[14]                       ] ^
+		      crc32_xfer_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = ((crc >> 24) ^ *d) & 0xff;
-		crc = (crc32_xfer_table[tbl_idx] ^ (crc << 8)) & 0xffffffff;
+		crc = (crc32_xfer_table[0][tbl_idx] ^ (crc << 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32_xfer/extconf.rb b/ext/digest/crc32_xfer/extconf.rb
index 978f559..61d8304 100644
--- a/ext/digest/crc32_xfer/extconf.rb
+++ b/ext/digest/crc32_xfer/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32_xfer_table.h", "crc32_xfer_table", 32, 0x000000af, false)
+
 create_header
 create_makefile "crc32_xfer_ext"
diff --git a/ext/digest/crc32c/crc32c.c b/ext/digest/crc32c/crc32c.c
index d0eaee7..36c66ab 100644
--- a/ext/digest/crc32c/crc32c.c
+++ b/ext/digest/crc32c/crc32c.c
@@ -15,54 +15,42 @@
  */
 
 #include "crc32c.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc32_t crc32c_table[256] = {
-	0x00000000, 0xf26b8303, 0xe13b70f7, 0x1350f3f4, 0xc79a971f, 0x35f1141c, 0x26a1e7e8, 0xd4ca64eb,
-	0x8ad958cf, 0x78b2dbcc, 0x6be22838, 0x9989ab3b, 0x4d43cfd0, 0xbf284cd3, 0xac78bf27, 0x5e133c24,
-	0x105ec76f, 0xe235446c, 0xf165b798, 0x030e349b, 0xd7c45070, 0x25afd373, 0x36ff2087, 0xc494a384,
-	0x9a879fa0, 0x68ec1ca3, 0x7bbcef57, 0x89d76c54, 0x5d1d08bf, 0xaf768bbc, 0xbc267848, 0x4e4dfb4b,
-	0x20bd8ede, 0xd2d60ddd, 0xc186fe29, 0x33ed7d2a, 0xe72719c1, 0x154c9ac2, 0x061c6936, 0xf477ea35,
-	0xaa64d611, 0x580f5512, 0x4b5fa6e6, 0xb93425e5, 0x6dfe410e, 0x9f95c20d, 0x8cc531f9, 0x7eaeb2fa,
-	0x30e349b1, 0xc288cab2, 0xd1d83946, 0x23b3ba45, 0xf779deae, 0x05125dad, 0x1642ae59, 0xe4292d5a,
-	0xba3a117e, 0x4851927d, 0x5b016189, 0xa96ae28a, 0x7da08661, 0x8fcb0562, 0x9c9bf696, 0x6ef07595,
-	0x417b1dbc, 0xb3109ebf, 0xa0406d4b, 0x522bee48, 0x86e18aa3, 0x748a09a0, 0x67dafa54, 0x95b17957,
-	0xcba24573, 0x39c9c670, 0x2a993584, 0xd8f2b687, 0x0c38d26c, 0xfe53516f, 0xed03a29b, 0x1f682198,
-	0x5125dad3, 0xa34e59d0, 0xb01eaa24, 0x42752927, 0x96bf4dcc, 0x64d4cecf, 0x77843d3b, 0x85efbe38,
-	0xdbfc821c, 0x2997011f, 0x3ac7f2eb, 0xc8ac71e8, 0x1c661503, 0xee0d9600, 0xfd5d65f4, 0x0f36e6f7,
-	0x61c69362, 0x93ad1061, 0x80fde395, 0x72966096, 0xa65c047d, 0x5437877e, 0x4767748a, 0xb50cf789,
-	0xeb1fcbad, 0x197448ae, 0x0a24bb5a, 0xf84f3859, 0x2c855cb2, 0xdeeedfb1, 0xcdbe2c45, 0x3fd5af46,
-	0x7198540d, 0x83f3d70e, 0x90a324fa, 0x62c8a7f9, 0xb602c312, 0x44694011, 0x5739b3e5, 0xa55230e6,
-	0xfb410cc2, 0x092a8fc1, 0x1a7a7c35, 0xe811ff36, 0x3cdb9bdd, 0xceb018de, 0xdde0eb2a, 0x2f8b6829,
-	0x82f63b78, 0x709db87b, 0x63cd4b8f, 0x91a6c88c, 0x456cac67, 0xb7072f64, 0xa457dc90, 0x563c5f93,
-	0x082f63b7, 0xfa44e0b4, 0xe9141340, 0x1b7f9043, 0xcfb5f4a8, 0x3dde77ab, 0x2e8e845f, 0xdce5075c,
-	0x92a8fc17, 0x60c37f14, 0x73938ce0, 0x81f80fe3, 0x55326b08, 0xa759e80b, 0xb4091bff, 0x466298fc,
-	0x1871a4d8, 0xea1a27db, 0xf94ad42f, 0x0b21572c, 0xdfeb33c7, 0x2d80b0c4, 0x3ed04330, 0xccbbc033,
-	0xa24bb5a6, 0x502036a5, 0x4370c551, 0xb11b4652, 0x65d122b9, 0x97baa1ba, 0x84ea524e, 0x7681d14d,
-	0x2892ed69, 0xdaf96e6a, 0xc9a99d9e, 0x3bc21e9d, 0xef087a76, 0x1d63f975, 0x0e330a81, 0xfc588982,
-	0xb21572c9, 0x407ef1ca, 0x532e023e, 0xa145813d, 0x758fe5d6, 0x87e466d5, 0x94b49521, 0x66df1622,
-	0x38cc2a06, 0xcaa7a905, 0xd9f75af1, 0x2b9cd9f2, 0xff56bd19, 0x0d3d3e1a, 0x1e6dcdee, 0xec064eed,
-	0xc38d26c4, 0x31e6a5c7, 0x22b65633, 0xd0ddd530, 0x0417b1db, 0xf67c32d8, 0xe52cc12c, 0x1747422f,
-	0x49547e0b, 0xbb3ffd08, 0xa86f0efc, 0x5a048dff, 0x8ecee914, 0x7ca56a17, 0x6ff599e3, 0x9d9e1ae0,
-	0xd3d3e1ab, 0x21b862a8, 0x32e8915c, 0xc083125f, 0x144976b4, 0xe622f5b7, 0xf5720643, 0x07198540,
-	0x590ab964, 0xab613a67, 0xb831c993, 0x4a5a4a90, 0x9e902e7b, 0x6cfbad78, 0x7fab5e8c, 0x8dc0dd8f,
-	0xe330a81a, 0x115b2b19, 0x020bd8ed, 0xf0605bee, 0x24aa3f05, 0xd6c1bc06, 0xc5914ff2, 0x37faccf1,
-	0x69e9f0d5, 0x9b8273d6, 0x88d28022, 0x7ab90321, 0xae7367ca, 0x5c18e4c9, 0x4f48173d, 0xbd23943e,
-	0xf36e6f75, 0x0105ec76, 0x12551f82, 0xe03e9c81, 0x34f4f86a, 0xc69f7b69, 0xd5cf889d, 0x27a40b9e,
-	0x79b737ba, 0x8bdcb4b9, 0x988c474d, 0x6ae7c44e, 0xbe2da0a5, 0x4c4623a6, 0x5f16d052, 0xad7d5351
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc32c_table.h"
 
 crc32_t crc32c_update(crc32_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc32c_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc32c_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc32c_table[13][d[ 2] ^ ((crc >> 16) & 0xff)] ^
+		      crc32c_table[12][d[ 3] ^ ((crc >> 24) & 0xff)] ^
+		      crc32c_table[11][d[ 4]                       ] ^
+		      crc32c_table[10][d[ 5]                       ] ^
+		      crc32c_table[ 9][d[ 6]                       ] ^
+		      crc32c_table[ 8][d[ 7]                       ] ^
+		      crc32c_table[ 7][d[ 8]                       ] ^
+		      crc32c_table[ 6][d[ 9]                       ] ^
+		      crc32c_table[ 5][d[10]                       ] ^
+		      crc32c_table[ 4][d[11]                       ] ^
+		      crc32c_table[ 3][d[12]                       ] ^
+		      crc32c_table[ 2][d[13]                       ] ^
+		      crc32c_table[ 1][d[14]                       ] ^
+		      crc32c_table[ 0][d[15]                       ];
+		crc &= 0xffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc32c_table[tbl_idx] ^ (crc >> 8)) & 0xffffffff;
+		crc = (crc32c_table[0][tbl_idx] ^ (crc >> 8)) & 0xffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc32c/extconf.rb b/ext/digest/crc32c/extconf.rb
index 5369e3f..b1ce351 100644
--- a/ext/digest/crc32c/extconf.rb
+++ b/ext/digest/crc32c/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc32c_table.h", "crc32c_table", 32, 0x1edc6f41, true)
+
 create_header
 create_makefile "crc32c_ext"
diff --git a/ext/digest/crc5/crc5.c b/ext/digest/crc5/crc5.c
index 66020f5..ce05e82 100644
--- a/ext/digest/crc5/crc5.c
+++ b/ext/digest/crc5/crc5.c
@@ -15,38 +15,42 @@
  */
 
 #include "crc5.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc5_t crc5_table[256] = {
-	0x00, 0x0e, 0x1c, 0x12, 0x11, 0x1f, 0x0d, 0x03, 0x0b, 0x05, 0x17, 0x19, 0x1a, 0x14, 0x06, 0x08,
-	0x16, 0x18, 0x0a, 0x04, 0x07, 0x09, 0x1b, 0x15, 0x1d, 0x13, 0x01, 0x0f, 0x0c, 0x02, 0x10, 0x1e,
-	0x05, 0x0b, 0x19, 0x17, 0x14, 0x1a, 0x08, 0x06, 0x0e, 0x00, 0x12, 0x1c, 0x1f, 0x11, 0x03, 0x0d,
-	0x13, 0x1d, 0x0f, 0x01, 0x02, 0x0c, 0x1e, 0x10, 0x18, 0x16, 0x04, 0x0a, 0x09, 0x07, 0x15, 0x1b,
-	0x0a, 0x04, 0x16, 0x18, 0x1b, 0x15, 0x07, 0x09, 0x01, 0x0f, 0x1d, 0x13, 0x10, 0x1e, 0x0c, 0x02,
-	0x1c, 0x12, 0x00, 0x0e, 0x0d, 0x03, 0x11, 0x1f, 0x17, 0x19, 0x0b, 0x05, 0x06, 0x08, 0x1a, 0x14,
-	0x0f, 0x01, 0x13, 0x1d, 0x1e, 0x10, 0x02, 0x0c, 0x04, 0x0a, 0x18, 0x16, 0x15, 0x1b, 0x09, 0x07,
-	0x19, 0x17, 0x05, 0x0b, 0x08, 0x06, 0x14, 0x1a, 0x12, 0x1c, 0x0e, 0x00, 0x03, 0x0d, 0x1f, 0x11,
-	0x14, 0x1a, 0x08, 0x06, 0x05, 0x0b, 0x19, 0x17, 0x1f, 0x11, 0x03, 0x0d, 0x0e, 0x00, 0x12, 0x1c,
-	0x02, 0x0c, 0x1e, 0x10, 0x13, 0x1d, 0x0f, 0x01, 0x09, 0x07, 0x15, 0x1b, 0x18, 0x16, 0x04, 0x0a,
-	0x11, 0x1f, 0x0d, 0x03, 0x00, 0x0e, 0x1c, 0x12, 0x1a, 0x14, 0x06, 0x08, 0x0b, 0x05, 0x17, 0x19,
-	0x07, 0x09, 0x1b, 0x15, 0x16, 0x18, 0x0a, 0x04, 0x0c, 0x02, 0x10, 0x1e, 0x1d, 0x13, 0x01, 0x0f,
-	0x1e, 0x10, 0x02, 0x0c, 0x0f, 0x01, 0x13, 0x1d, 0x15, 0x1b, 0x09, 0x07, 0x04, 0x0a, 0x18, 0x16,
-	0x08, 0x06, 0x14, 0x1a, 0x19, 0x17, 0x05, 0x0b, 0x03, 0x0d, 0x1f, 0x11, 0x12, 0x1c, 0x0e, 0x00,
-	0x1b, 0x15, 0x07, 0x09, 0x0a, 0x04, 0x16, 0x18, 0x10, 0x1e, 0x0c, 0x02, 0x01, 0x0f, 0x1d, 0x13,
-	0x0d, 0x03, 0x11, 0x1f, 0x1c, 0x12, 0x00, 0x0e, 0x06, 0x08, 0x1a, 0x14, 0x17, 0x19, 0x0b, 0x05
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc5_table.h"
 
 crc5_t crc5_update(crc5_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc5_table[15][d[ 0] ^ crc] ^
+		      crc5_table[14][d[ 1]      ] ^
+		      crc5_table[13][d[ 2]      ] ^
+		      crc5_table[12][d[ 3]      ] ^
+		      crc5_table[11][d[ 4]      ] ^
+		      crc5_table[10][d[ 5]      ] ^
+		      crc5_table[ 9][d[ 6]      ] ^
+		      crc5_table[ 8][d[ 7]      ] ^
+		      crc5_table[ 7][d[ 8]      ] ^
+		      crc5_table[ 6][d[ 9]      ] ^
+		      crc5_table[ 5][d[10]      ] ^
+		      crc5_table[ 4][d[11]      ] ^
+		      crc5_table[ 3][d[12]      ] ^
+		      crc5_table[ 2][d[13]      ] ^
+		      crc5_table[ 1][d[14]      ] ^
+		      crc5_table[ 0][d[15]      ];
+		crc &= 0x1f;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
-		tbl_idx = crc ^ *d;
-		crc = (crc5_table[tbl_idx] ^ (crc >> 8)) & 0x1f;
+		tbl_idx = (crc ^ *d) & 0xff;
+		crc = (crc5_table[0][tbl_idx]) & 0x1f;
 		d++;
 	}
 
diff --git a/ext/digest/crc5/extconf.rb b/ext/digest/crc5/extconf.rb
index 84feb26..94a3b7e 100644
--- a/ext/digest/crc5/extconf.rb
+++ b/ext/digest/crc5/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc5_table.h", "crc5_table", 5, 0x05, true)
+
 create_header
 create_makefile "crc5_ext"
diff --git a/ext/digest/crc64/crc64.c b/ext/digest/crc64/crc64.c
index ea3a7e4..cbdef35 100644
--- a/ext/digest/crc64/crc64.c
+++ b/ext/digest/crc64/crc64.c
@@ -15,86 +15,42 @@
  */
 
 #include "crc64.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc64_t crc64_table[256] = {
-	0x0000000000000000, 0x01b0000000000000, 0x0360000000000000, 0x02d0000000000000,
-	0x06c0000000000000, 0x0770000000000000, 0x05a0000000000000, 0x0410000000000000,
-	0x0d80000000000000, 0x0c30000000000000, 0x0ee0000000000000, 0x0f50000000000000,
-	0x0b40000000000000, 0x0af0000000000000, 0x0820000000000000, 0x0990000000000000,
-	0x1b00000000000000, 0x1ab0000000000000, 0x1860000000000000, 0x19d0000000000000,
-	0x1dc0000000000000, 0x1c70000000000000, 0x1ea0000000000000, 0x1f10000000000000,
-	0x1680000000000000, 0x1730000000000000, 0x15e0000000000000, 0x1450000000000000,
-	0x1040000000000000, 0x11f0000000000000, 0x1320000000000000, 0x1290000000000000,
-	0x3600000000000000, 0x37b0000000000000, 0x3560000000000000, 0x34d0000000000000,
-	0x30c0000000000000, 0x3170000000000000, 0x33a0000000000000, 0x3210000000000000,
-	0x3b80000000000000, 0x3a30000000000000, 0x38e0000000000000, 0x3950000000000000,
-	0x3d40000000000000, 0x3cf0000000000000, 0x3e20000000000000, 0x3f90000000000000,
-	0x2d00000000000000, 0x2cb0000000000000, 0x2e60000000000000, 0x2fd0000000000000,
-	0x2bc0000000000000, 0x2a70000000000000, 0x28a0000000000000, 0x2910000000000000,
-	0x2080000000000000, 0x2130000000000000, 0x23e0000000000000, 0x2250000000000000,
-	0x2640000000000000, 0x27f0000000000000, 0x2520000000000000, 0x2490000000000000,
-	0x6c00000000000000, 0x6db0000000000000, 0x6f60000000000000, 0x6ed0000000000000,
-	0x6ac0000000000000, 0x6b70000000000000, 0x69a0000000000000, 0x6810000000000000,
-	0x6180000000000000, 0x6030000000000000, 0x62e0000000000000, 0x6350000000000000,
-	0x6740000000000000, 0x66f0000000000000, 0x6420000000000000, 0x6590000000000000,
-	0x7700000000000000, 0x76b0000000000000, 0x7460000000000000, 0x75d0000000000000,
-	0x71c0000000000000, 0x7070000000000000, 0x72a0000000000000, 0x7310000000000000,
-	0x7a80000000000000, 0x7b30000000000000, 0x79e0000000000000, 0x7850000000000000,
-	0x7c40000000000000, 0x7df0000000000000, 0x7f20000000000000, 0x7e90000000000000,
-	0x5a00000000000000, 0x5bb0000000000000, 0x5960000000000000, 0x58d0000000000000,
-	0x5cc0000000000000, 0x5d70000000000000, 0x5fa0000000000000, 0x5e10000000000000,
-	0x5780000000000000, 0x5630000000000000, 0x54e0000000000000, 0x5550000000000000,
-	0x5140000000000000, 0x50f0000000000000, 0x5220000000000000, 0x5390000000000000,
-	0x4100000000000000, 0x40b0000000000000, 0x4260000000000000, 0x43d0000000000000,
-	0x47c0000000000000, 0x4670000000000000, 0x44a0000000000000, 0x4510000000000000,
-	0x4c80000000000000, 0x4d30000000000000, 0x4fe0000000000000, 0x4e50000000000000,
-	0x4a40000000000000, 0x4bf0000000000000, 0x4920000000000000, 0x4890000000000000,
-	0xd800000000000000, 0xd9b0000000000000, 0xdb60000000000000, 0xdad0000000000000,
-	0xdec0000000000000, 0xdf70000000000000, 0xdda0000000000000, 0xdc10000000000000,
-	0xd580000000000000, 0xd430000000000000, 0xd6e0000000000000, 0xd750000000000000,
-	0xd340000000000000, 0xd2f0000000000000, 0xd020000000000000, 0xd190000000000000,
-	0xc300000000000000, 0xc2b0000000000000, 0xc060000000000000, 0xc1d0000000000000,
-	0xc5c0000000000000, 0xc470000000000000, 0xc6a0000000000000, 0xc710000000000000,
-	0xce80000000000000, 0xcf30000000000000, 0xcde0000000000000, 0xcc50000000000000,
-	0xc840000000000000, 0xc9f0000000000000, 0xcb20000000000000, 0xca90000000000000,
-	0xee00000000000000, 0xefb0000000000000, 0xed60000000000000, 0xecd0000000000000,
-	0xe8c0000000000000, 0xe970000000000000, 0xeba0000000000000, 0xea10000000000000,
-	0xe380000000000000, 0xe230000000000000, 0xe0e0000000000000, 0xe150000000000000,
-	0xe540000000000000, 0xe4f0000000000000, 0xe620000000000000, 0xe790000000000000,
-	0xf500000000000000, 0xf4b0000000000000, 0xf660000000000000, 0xf7d0000000000000,
-	0xf3c0000000000000, 0xf270000000000000, 0xf0a0000000000000, 0xf110000000000000,
-	0xf880000000000000, 0xf930000000000000, 0xfbe0000000000000, 0xfa50000000000000,
-	0xfe40000000000000, 0xfff0000000000000, 0xfd20000000000000, 0xfc90000000000000,
-	0xb400000000000000, 0xb5b0000000000000, 0xb760000000000000, 0xb6d0000000000000,
-	0xb2c0000000000000, 0xb370000000000000, 0xb1a0000000000000, 0xb010000000000000,
-	0xb980000000000000, 0xb830000000000000, 0xbae0000000000000, 0xbb50000000000000,
-	0xbf40000000000000, 0xbef0000000000000, 0xbc20000000000000, 0xbd90000000000000,
-	0xaf00000000000000, 0xaeb0000000000000, 0xac60000000000000, 0xadd0000000000000,
-	0xa9c0000000000000, 0xa870000000000000, 0xaaa0000000000000, 0xab10000000000000,
-	0xa280000000000000, 0xa330000000000000, 0xa1e0000000000000, 0xa050000000000000,
-	0xa440000000000000, 0xa5f0000000000000, 0xa720000000000000, 0xa690000000000000,
-	0x8200000000000000, 0x83b0000000000000, 0x8160000000000000, 0x80d0000000000000,
-	0x84c0000000000000, 0x8570000000000000, 0x87a0000000000000, 0x8610000000000000,
-	0x8f80000000000000, 0x8e30000000000000, 0x8ce0000000000000, 0x8d50000000000000,
-	0x8940000000000000, 0x88f0000000000000, 0x8a20000000000000, 0x8b90000000000000,
-	0x9900000000000000, 0x98b0000000000000, 0x9a60000000000000, 0x9bd0000000000000,
-	0x9fc0000000000000, 0x9e70000000000000, 0x9ca0000000000000, 0x9d10000000000000,
-	0x9480000000000000, 0x9530000000000000, 0x97e0000000000000, 0x9650000000000000,
-	0x9240000000000000, 0x93f0000000000000, 0x9120000000000000, 0x9090000000000000
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc64_table.h"
 
 crc64_t crc64_update(crc64_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc64_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc64_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc64_table[13][d[ 2] ^ ((crc >> 16) & 0xff)] ^
+		      crc64_table[12][d[ 3] ^ ((crc >> 24) & 0xff)] ^
+		      crc64_table[11][d[ 4] ^ ((crc >> 32) & 0xff)] ^
+		      crc64_table[10][d[ 5] ^ ((crc >> 40) & 0xff)] ^
+		      crc64_table[ 9][d[ 6] ^ ((crc >> 48) & 0xff)] ^
+		      crc64_table[ 8][d[ 7] ^ ((crc >> 56) & 0xff)] ^
+		      crc64_table[ 7][d[ 8]                       ] ^
+		      crc64_table[ 6][d[ 9]                       ] ^
+		      crc64_table[ 5][d[10]                       ] ^
+		      crc64_table[ 4][d[11]                       ] ^
+		      crc64_table[ 3][d[12]                       ] ^
+		      crc64_table[ 2][d[13]                       ] ^
+		      crc64_table[ 1][d[14]                       ] ^
+		      crc64_table[ 0][d[15]                       ];
+		crc &= 0xffffffffffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc64_table[tbl_idx] ^ (crc >> 8)) & 0xffffffffffffffff;
+		crc = (crc64_table[0][tbl_idx] ^ (crc >> 8)) & 0xffffffffffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc64/extconf.rb b/ext/digest/crc64/extconf.rb
index d0f1f8a..10c4cfc 100644
--- a/ext/digest/crc64/extconf.rb
+++ b/ext/digest/crc64/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc64_table.h", "crc64_table", 64, 0x000000000000001b, true)
+
 create_header
 create_makefile "crc64_ext"
diff --git a/ext/digest/crc64_jones/crc64_jones.c b/ext/digest/crc64_jones/crc64_jones.c
index 7f0232c..9e4cb39 100644
--- a/ext/digest/crc64_jones/crc64_jones.c
+++ b/ext/digest/crc64_jones/crc64_jones.c
@@ -15,86 +15,42 @@
  */
 
 #include "crc64_jones.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc64_t crc64_table[256] = {
-	0x0000000000000000, 0x7ad870c830358979, 0xf5b0e190606b12f2, 0x8f689158505e9b8b,
-	0xc038e5739841b68f, 0xbae095bba8743ff6, 0x358804e3f82aa47d, 0x4f50742bc81f2d04,
-	0xab28ecb46814fe75, 0xd1f09c7c5821770c, 0x5e980d24087fec87, 0x24407dec384a65fe,
-	0x6b1009c7f05548fa, 0x11c8790fc060c183, 0x9ea0e857903e5a08, 0xe478989fa00bd371,
-	0x7d08ff3b88be6f81, 0x07d08ff3b88be6f8, 0x88b81eabe8d57d73, 0xf2606e63d8e0f40a,
-	0xbd301a4810ffd90e, 0xc7e86a8020ca5077, 0x4880fbd87094cbfc, 0x32588b1040a14285,
-	0xd620138fe0aa91f4, 0xacf86347d09f188d, 0x2390f21f80c18306, 0x594882d7b0f40a7f,
-	0x1618f6fc78eb277b, 0x6cc0863448deae02, 0xe3a8176c18803589, 0x997067a428b5bcf0,
-	0xfa11fe77117cdf02, 0x80c98ebf2149567b, 0x0fa11fe77117cdf0, 0x75796f2f41224489,
-	0x3a291b04893d698d, 0x40f16bccb908e0f4, 0xcf99fa94e9567b7f, 0xb5418a5cd963f206,
-	0x513912c379682177, 0x2be1620b495da80e, 0xa489f35319033385, 0xde51839b2936bafc,
-	0x9101f7b0e12997f8, 0xebd98778d11c1e81, 0x64b116208142850a, 0x1e6966e8b1770c73,
-	0x8719014c99c2b083, 0xfdc17184a9f739fa, 0x72a9e0dcf9a9a271, 0x08719014c99c2b08,
-	0x4721e43f0183060c, 0x3df994f731b68f75, 0xb29105af61e814fe, 0xc849756751dd9d87,
-	0x2c31edf8f1d64ef6, 0x56e99d30c1e3c78f, 0xd9810c6891bd5c04, 0xa3597ca0a188d57d,
-	0xec09088b6997f879, 0x96d1784359a27100, 0x19b9e91b09fcea8b, 0x636199d339c963f2,
-	0xdf7adabd7a6e2d6f, 0xa5a2aa754a5ba416, 0x2aca3b2d1a053f9d, 0x50124be52a30b6e4,
-	0x1f423fcee22f9be0, 0x659a4f06d21a1299, 0xeaf2de5e82448912, 0x902aae96b271006b,
-	0x74523609127ad31a, 0x0e8a46c1224f5a63, 0x81e2d7997211c1e8, 0xfb3aa75142244891,
-	0xb46ad37a8a3b6595, 0xceb2a3b2ba0eecec, 0x41da32eaea507767, 0x3b024222da65fe1e,
-	0xa2722586f2d042ee, 0xd8aa554ec2e5cb97, 0x57c2c41692bb501c, 0x2d1ab4dea28ed965,
-	0x624ac0f56a91f461, 0x1892b03d5aa47d18, 0x97fa21650afae693, 0xed2251ad3acf6fea,
-	0x095ac9329ac4bc9b, 0x7382b9faaaf135e2, 0xfcea28a2faafae69, 0x8632586aca9a2710,
-	0xc9622c4102850a14, 0xb3ba5c8932b0836d, 0x3cd2cdd162ee18e6, 0x460abd1952db919f,
-	0x256b24ca6b12f26d, 0x5fb354025b277b14, 0xd0dbc55a0b79e09f, 0xaa03b5923b4c69e6,
-	0xe553c1b9f35344e2, 0x9f8bb171c366cd9b, 0x10e3202993385610, 0x6a3b50e1a30ddf69,
-	0x8e43c87e03060c18, 0xf49bb8b633338561, 0x7bf329ee636d1eea, 0x012b592653589793,
-	0x4e7b2d0d9b47ba97, 0x34a35dc5ab7233ee, 0xbbcbcc9dfb2ca865, 0xc113bc55cb19211c,
-	0x5863dbf1e3ac9dec, 0x22bbab39d3991495, 0xadd33a6183c78f1e, 0xd70b4aa9b3f20667,
-	0x985b3e827bed2b63, 0xe2834e4a4bd8a21a, 0x6debdf121b863991, 0x1733afda2bb3b0e8,
-	0xf34b37458bb86399, 0x8993478dbb8deae0, 0x06fbd6d5ebd3716b, 0x7c23a61ddbe6f812,
-	0x3373d23613f9d516, 0x49aba2fe23cc5c6f, 0xc6c333a67392c7e4, 0xbc1b436e43a74e9d,
-	0x95ac9329ac4bc9b5, 0xef74e3e19c7e40cc, 0x601c72b9cc20db47, 0x1ac40271fc15523e,
-	0x5594765a340a7f3a, 0x2f4c0692043ff643, 0xa02497ca54616dc8, 0xdafce7026454e4b1,
-	0x3e847f9dc45f37c0, 0x445c0f55f46abeb9, 0xcb349e0da4342532, 0xb1eceec59401ac4b,
-	0xfebc9aee5c1e814f, 0x8464ea266c2b0836, 0x0b0c7b7e3c7593bd, 0x71d40bb60c401ac4,
-	0xe8a46c1224f5a634, 0x927c1cda14c02f4d, 0x1d148d82449eb4c6, 0x67ccfd4a74ab3dbf,
-	0x289c8961bcb410bb, 0x5244f9a98c8199c2, 0xdd2c68f1dcdf0249, 0xa7f41839ecea8b30,
-	0x438c80a64ce15841, 0x3954f06e7cd4d138, 0xb63c61362c8a4ab3, 0xcce411fe1cbfc3ca,
-	0x83b465d5d4a0eece, 0xf96c151de49567b7, 0x76048445b4cbfc3c, 0x0cdcf48d84fe7545,
-	0x6fbd6d5ebd3716b7, 0x15651d968d029fce, 0x9a0d8ccedd5c0445, 0xe0d5fc06ed698d3c,
-	0xaf85882d2576a038, 0xd55df8e515432941, 0x5a3569bd451db2ca, 0x20ed197575283bb3,
-	0xc49581ead523e8c2, 0xbe4df122e51661bb, 0x3125607ab548fa30, 0x4bfd10b2857d7349,
-	0x04ad64994d625e4d, 0x7e7514517d57d734, 0xf11d85092d094cbf, 0x8bc5f5c11d3cc5c6,
-	0x12b5926535897936, 0x686de2ad05bcf04f, 0xe70573f555e26bc4, 0x9ddd033d65d7e2bd,
-	0xd28d7716adc8cfb9, 0xa85507de9dfd46c0, 0x273d9686cda3dd4b, 0x5de5e64efd965432,
-	0xb99d7ed15d9d8743, 0xc3450e196da80e3a, 0x4c2d9f413df695b1, 0x36f5ef890dc31cc8,
-	0x79a59ba2c5dc31cc, 0x037deb6af5e9b8b5, 0x8c157a32a5b7233e, 0xf6cd0afa9582aa47,
-	0x4ad64994d625e4da, 0x300e395ce6106da3, 0xbf66a804b64ef628, 0xc5bed8cc867b7f51,
-	0x8aeeace74e645255, 0xf036dc2f7e51db2c, 0x7f5e4d772e0f40a7, 0x05863dbf1e3ac9de,
-	0xe1fea520be311aaf, 0x9b26d5e88e0493d6, 0x144e44b0de5a085d, 0x6e963478ee6f8124,
-	0x21c640532670ac20, 0x5b1e309b16452559, 0xd476a1c3461bbed2, 0xaeaed10b762e37ab,
-	0x37deb6af5e9b8b5b, 0x4d06c6676eae0222, 0xc26e573f3ef099a9, 0xb8b627f70ec510d0,
-	0xf7e653dcc6da3dd4, 0x8d3e2314f6efb4ad, 0x0256b24ca6b12f26, 0x788ec2849684a65f,
-	0x9cf65a1b368f752e, 0xe62e2ad306bafc57, 0x6946bb8b56e467dc, 0x139ecb4366d1eea5,
-	0x5ccebf68aecec3a1, 0x2616cfa09efb4ad8, 0xa97e5ef8cea5d153, 0xd3a62e30fe90582a,
-	0xb0c7b7e3c7593bd8, 0xca1fc72bf76cb2a1, 0x45775673a732292a, 0x3faf26bb9707a053,
-	0x70ff52905f188d57, 0x0a2722586f2d042e, 0x854fb3003f739fa5, 0xff97c3c80f4616dc,
-	0x1bef5b57af4dc5ad, 0x61372b9f9f784cd4, 0xee5fbac7cf26d75f, 0x9487ca0fff135e26,
-	0xdbd7be24370c7322, 0xa10fceec0739fa5b, 0x2e675fb4576761d0, 0x54bf2f7c6752e8a9,
-	0xcdcf48d84fe75459, 0xb71738107fd2dd20, 0x387fa9482f8c46ab, 0x42a7d9801fb9cfd2,
-	0x0df7adabd7a6e2d6, 0x772fdd63e7936baf, 0xf8474c3bb7cdf024, 0x829f3cf387f8795d,
-	0x66e7a46c27f3aa2c, 0x1c3fd4a417c62355, 0x935745fc4798b8de, 0xe98f353477ad31a7,
-	0xa6df411fbfb21ca3, 0xdc0731d78f8795da, 0x536fa08fdfd90e51, 0x29b7d047efec8728
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc64_jones_table.h"
 
 crc64_t crc64_jones_update(crc64_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc64_jones_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc64_jones_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc64_jones_table[13][d[ 2] ^ ((crc >> 16) & 0xff)] ^
+		      crc64_jones_table[12][d[ 3] ^ ((crc >> 24) & 0xff)] ^
+		      crc64_jones_table[11][d[ 4] ^ ((crc >> 32) & 0xff)] ^
+		      crc64_jones_table[10][d[ 5] ^ ((crc >> 40) & 0xff)] ^
+		      crc64_jones_table[ 9][d[ 6] ^ ((crc >> 48) & 0xff)] ^
+		      crc64_jones_table[ 8][d[ 7] ^ ((crc >> 56) & 0xff)] ^
+		      crc64_jones_table[ 7][d[ 8]                       ] ^
+		      crc64_jones_table[ 6][d[ 9]                       ] ^
+		      crc64_jones_table[ 5][d[10]                       ] ^
+		      crc64_jones_table[ 4][d[11]                       ] ^
+		      crc64_jones_table[ 3][d[12]                       ] ^
+		      crc64_jones_table[ 2][d[13]                       ] ^
+		      crc64_jones_table[ 1][d[14]                       ] ^
+		      crc64_jones_table[ 0][d[15]                       ];
+		crc &= 0xffffffffffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc64_table[tbl_idx] ^ (crc >> 8)) & 0xffffffffffffffff;
+		crc = (crc64_jones_table[0][tbl_idx] ^ (crc >> 8)) & 0xffffffffffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc64_jones/extconf.rb b/ext/digest/crc64_jones/extconf.rb
index 70cff91..ab9fa62 100644
--- a/ext/digest/crc64_jones/extconf.rb
+++ b/ext/digest/crc64_jones/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc64_jones_table.h", "crc64_jones_table", 64, 0xad93d23594c935a9, true)
+
 create_header
 create_makefile "crc64_jones_ext"
diff --git a/ext/digest/crc64_xz/crc64_xz.c b/ext/digest/crc64_xz/crc64_xz.c
index c076512..ce75d00 100644
--- a/ext/digest/crc64_xz/crc64_xz.c
+++ b/ext/digest/crc64_xz/crc64_xz.c
@@ -15,86 +15,42 @@
  */
 
 #include "crc64_xz.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc64_t crc64_table[256] = {
-	0x0000000000000000, 0xb32e4cbe03a75f6f, 0xf4843657a840a05b, 0x47aa7ae9abe7ff34,
-	0x7bd0c384ff8f5e33, 0xc8fe8f3afc28015c, 0x8f54f5d357cffe68, 0x3c7ab96d5468a107,
-	0xf7a18709ff1ebc66, 0x448fcbb7fcb9e309, 0x0325b15e575e1c3d, 0xb00bfde054f94352,
-	0x8c71448d0091e255, 0x3f5f08330336bd3a, 0x78f572daa8d1420e, 0xcbdb3e64ab761d61,
-	0x7d9ba13851336649, 0xceb5ed8652943926, 0x891f976ff973c612, 0x3a31dbd1fad4997d,
-	0x064b62bcaebc387a, 0xb5652e02ad1b6715, 0xf2cf54eb06fc9821, 0x41e11855055bc74e,
-	0x8a3a2631ae2dda2f, 0x39146a8fad8a8540, 0x7ebe1066066d7a74, 0xcd905cd805ca251b,
-	0xf1eae5b551a2841c, 0x42c4a90b5205db73, 0x056ed3e2f9e22447, 0xb6409f5cfa457b28,
-	0xfb374270a266cc92, 0x48190ecea1c193fd, 0x0fb374270a266cc9, 0xbc9d3899098133a6,
-	0x80e781f45de992a1, 0x33c9cd4a5e4ecdce, 0x7463b7a3f5a932fa, 0xc74dfb1df60e6d95,
-	0x0c96c5795d7870f4, 0xbfb889c75edf2f9b, 0xf812f32ef538d0af, 0x4b3cbf90f69f8fc0,
-	0x774606fda2f72ec7, 0xc4684a43a15071a8, 0x83c230aa0ab78e9c, 0x30ec7c140910d1f3,
-	0x86ace348f355aadb, 0x3582aff6f0f2f5b4, 0x7228d51f5b150a80, 0xc10699a158b255ef,
-	0xfd7c20cc0cdaf4e8, 0x4e526c720f7dab87, 0x09f8169ba49a54b3, 0xbad65a25a73d0bdc,
-	0x710d64410c4b16bd, 0xc22328ff0fec49d2, 0x85895216a40bb6e6, 0x36a71ea8a7ace989,
-	0x0adda7c5f3c4488e, 0xb9f3eb7bf06317e1, 0xfe5991925b84e8d5, 0x4d77dd2c5823b7ba,
-	0x64b62bcaebc387a1, 0xd7986774e864d8ce, 0x90321d9d438327fa, 0x231c512340247895,
-	0x1f66e84e144cd992, 0xac48a4f017eb86fd, 0xebe2de19bc0c79c9, 0x58cc92a7bfab26a6,
-	0x9317acc314dd3bc7, 0x2039e07d177a64a8, 0x67939a94bc9d9b9c, 0xd4bdd62abf3ac4f3,
-	0xe8c76f47eb5265f4, 0x5be923f9e8f53a9b, 0x1c4359104312c5af, 0xaf6d15ae40b59ac0,
-	0x192d8af2baf0e1e8, 0xaa03c64cb957be87, 0xeda9bca512b041b3, 0x5e87f01b11171edc,
-	0x62fd4976457fbfdb, 0xd1d305c846d8e0b4, 0x96797f21ed3f1f80, 0x2557339fee9840ef,
-	0xee8c0dfb45ee5d8e, 0x5da24145464902e1, 0x1a083bacedaefdd5, 0xa9267712ee09a2ba,
-	0x955cce7fba6103bd, 0x267282c1b9c65cd2, 0x61d8f8281221a3e6, 0xd2f6b4961186fc89,
-	0x9f8169ba49a54b33, 0x2caf25044a02145c, 0x6b055fede1e5eb68, 0xd82b1353e242b407,
-	0xe451aa3eb62a1500, 0x577fe680b58d4a6f, 0x10d59c691e6ab55b, 0xa3fbd0d71dcdea34,
-	0x6820eeb3b6bbf755, 0xdb0ea20db51ca83a, 0x9ca4d8e41efb570e, 0x2f8a945a1d5c0861,
-	0x13f02d374934a966, 0xa0de61894a93f609, 0xe7741b60e174093d, 0x545a57dee2d35652,
-	0xe21ac88218962d7a, 0x5134843c1b317215, 0x169efed5b0d68d21, 0xa5b0b26bb371d24e,
-	0x99ca0b06e7197349, 0x2ae447b8e4be2c26, 0x6d4e3d514f59d312, 0xde6071ef4cfe8c7d,
-	0x15bb4f8be788911c, 0xa6950335e42fce73, 0xe13f79dc4fc83147, 0x521135624c6f6e28,
-	0x6e6b8c0f1807cf2f, 0xdd45c0b11ba09040, 0x9aefba58b0476f74, 0x29c1f6e6b3e0301b,
-	0xc96c5795d7870f42, 0x7a421b2bd420502d, 0x3de861c27fc7af19, 0x8ec62d7c7c60f076,
-	0xb2bc941128085171, 0x0192d8af2baf0e1e, 0x4638a2468048f12a, 0xf516eef883efae45,
-	0x3ecdd09c2899b324, 0x8de39c222b3eec4b, 0xca49e6cb80d9137f, 0x7967aa75837e4c10,
-	0x451d1318d716ed17, 0xf6335fa6d4b1b278, 0xb199254f7f564d4c, 0x02b769f17cf11223,
-	0xb4f7f6ad86b4690b, 0x07d9ba1385133664, 0x4073c0fa2ef4c950, 0xf35d8c442d53963f,
-	0xcf273529793b3738, 0x7c0979977a9c6857, 0x3ba3037ed17b9763, 0x888d4fc0d2dcc80c,
-	0x435671a479aad56d, 0xf0783d1a7a0d8a02, 0xb7d247f3d1ea7536, 0x04fc0b4dd24d2a59,
-	0x3886b22086258b5e, 0x8ba8fe9e8582d431, 0xcc0284772e652b05, 0x7f2cc8c92dc2746a,
-	0x325b15e575e1c3d0, 0x8175595b76469cbf, 0xc6df23b2dda1638b, 0x75f16f0cde063ce4,
-	0x498bd6618a6e9de3, 0xfaa59adf89c9c28c, 0xbd0fe036222e3db8, 0x0e21ac88218962d7,
-	0xc5fa92ec8aff7fb6, 0x76d4de52895820d9, 0x317ea4bb22bfdfed, 0x8250e80521188082,
-	0xbe2a516875702185, 0x0d041dd676d77eea, 0x4aae673fdd3081de, 0xf9802b81de97deb1,
-	0x4fc0b4dd24d2a599, 0xfceef8632775faf6, 0xbb44828a8c9205c2, 0x086ace348f355aad,
-	0x34107759db5dfbaa, 0x873e3be7d8faa4c5, 0xc094410e731d5bf1, 0x73ba0db070ba049e,
-	0xb86133d4dbcc19ff, 0x0b4f7f6ad86b4690, 0x4ce50583738cb9a4, 0xffcb493d702be6cb,
-	0xc3b1f050244347cc, 0x709fbcee27e418a3, 0x3735c6078c03e797, 0x841b8ab98fa4b8f8,
-	0xadda7c5f3c4488e3, 0x1ef430e13fe3d78c, 0x595e4a08940428b8, 0xea7006b697a377d7,
-	0xd60abfdbc3cbd6d0, 0x6524f365c06c89bf, 0x228e898c6b8b768b, 0x91a0c532682c29e4,
-	0x5a7bfb56c35a3485, 0xe955b7e8c0fd6bea, 0xaeffcd016b1a94de, 0x1dd181bf68bdcbb1,
-	0x21ab38d23cd56ab6, 0x9285746c3f7235d9, 0xd52f0e859495caed, 0x6601423b97329582,
-	0xd041dd676d77eeaa, 0x636f91d96ed0b1c5, 0x24c5eb30c5374ef1, 0x97eba78ec690119e,
-	0xab911ee392f8b099, 0x18bf525d915feff6, 0x5f1528b43ab810c2, 0xec3b640a391f4fad,
-	0x27e05a6e926952cc, 0x94ce16d091ce0da3, 0xd3646c393a29f297, 0x604a2087398eadf8,
-	0x5c3099ea6de60cff, 0xef1ed5546e415390, 0xa8b4afbdc5a6aca4, 0x1b9ae303c601f3cb,
-	0x56ed3e2f9e224471, 0xe5c372919d851b1e, 0xa26908783662e42a, 0x114744c635c5bb45,
-	0x2d3dfdab61ad1a42, 0x9e13b115620a452d, 0xd9b9cbfcc9edba19, 0x6a978742ca4ae576,
-	0xa14cb926613cf817, 0x1262f598629ba778, 0x55c88f71c97c584c, 0xe6e6c3cfcadb0723,
-	0xda9c7aa29eb3a624, 0x69b2361c9d14f94b, 0x2e184cf536f3067f, 0x9d36004b35545910,
-	0x2b769f17cf112238, 0x9858d3a9ccb67d57, 0xdff2a94067518263, 0x6cdce5fe64f6dd0c,
-	0x50a65c93309e7c0b, 0xe388102d33392364, 0xa4226ac498dedc50, 0x170c267a9b79833f,
-	0xdcd7181e300f9e5e, 0x6ff954a033a8c131, 0x28532e49984f3e05, 0x9b7d62f79be8616a,
-	0xa707db9acf80c06d, 0x14299724cc279f02, 0x5383edcd67c06036, 0xe0ada17364673f59
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc64_xz_table.h"
 
 crc64_t crc64_xz_update(crc64_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc64_xz_table[15][d[ 0] ^ ((crc >>  0) & 0xff)] ^
+		      crc64_xz_table[14][d[ 1] ^ ((crc >>  8) & 0xff)] ^
+		      crc64_xz_table[13][d[ 2] ^ ((crc >> 16) & 0xff)] ^
+		      crc64_xz_table[12][d[ 3] ^ ((crc >> 24) & 0xff)] ^
+		      crc64_xz_table[11][d[ 4] ^ ((crc >> 32) & 0xff)] ^
+		      crc64_xz_table[10][d[ 5] ^ ((crc >> 40) & 0xff)] ^
+		      crc64_xz_table[ 9][d[ 6] ^ ((crc >> 48) & 0xff)] ^
+		      crc64_xz_table[ 8][d[ 7] ^ ((crc >> 56) & 0xff)] ^
+		      crc64_xz_table[ 7][d[ 8]                       ] ^
+		      crc64_xz_table[ 6][d[ 9]                       ] ^
+		      crc64_xz_table[ 5][d[10]                       ] ^
+		      crc64_xz_table[ 4][d[11]                       ] ^
+		      crc64_xz_table[ 3][d[12]                       ] ^
+		      crc64_xz_table[ 2][d[13]                       ] ^
+		      crc64_xz_table[ 1][d[14]                       ] ^
+		      crc64_xz_table[ 0][d[15]                       ];
+		crc &= 0xffffffffffffffff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
 		tbl_idx = (crc ^ *d) & 0xff;
-		crc = (crc64_table[tbl_idx] ^ (crc >> 8)) & 0xffffffffffffffff;
+		crc = (crc64_xz_table[0][tbl_idx] ^ (crc >> 8)) & 0xffffffffffffffff;
 		d++;
 	}
 
diff --git a/ext/digest/crc64_xz/extconf.rb b/ext/digest/crc64_xz/extconf.rb
index 621cd2e..690c23b 100644
--- a/ext/digest/crc64_xz/extconf.rb
+++ b/ext/digest/crc64_xz/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc64_xz_table.h", "crc64_xz_table", 64, 0x42f0e1eba9ea3693, true)
+
 create_header
 create_makefile "crc64_xz_ext"
diff --git a/ext/digest/crc8/crc8.c b/ext/digest/crc8/crc8.c
index 7042bf8..9e58c86 100644
--- a/ext/digest/crc8/crc8.c
+++ b/ext/digest/crc8/crc8.c
@@ -15,38 +15,42 @@
  */
 
 #include "crc8.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc8_t crc8_1wire_table[256] = {
-	0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15, 0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
-	0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65, 0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
-	0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5, 0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
-	0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85, 0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
-	0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2, 0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
-	0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2, 0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
-	0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32, 0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
-	0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42, 0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
-	0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c, 0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
-	0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec, 0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
-	0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c, 0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
-	0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c, 0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
-	0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b, 0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
-	0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b, 0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
-	0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb, 0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
-	0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb, 0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc8_table.h"
 
 crc8_t crc8_update(crc8_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc8_table[15][d[ 0] ^ crc] ^
+		      crc8_table[14][d[ 1]      ] ^
+		      crc8_table[13][d[ 2]      ] ^
+		      crc8_table[12][d[ 3]      ] ^
+		      crc8_table[11][d[ 4]      ] ^
+		      crc8_table[10][d[ 5]      ] ^
+		      crc8_table[ 9][d[ 6]      ] ^
+		      crc8_table[ 8][d[ 7]      ] ^
+		      crc8_table[ 7][d[ 8]      ] ^
+		      crc8_table[ 6][d[ 9]      ] ^
+		      crc8_table[ 5][d[10]      ] ^
+		      crc8_table[ 4][d[11]      ] ^
+		      crc8_table[ 3][d[12]      ] ^
+		      crc8_table[ 2][d[13]      ] ^
+		      crc8_table[ 1][d[14]      ] ^
+		      crc8_table[ 0][d[15]      ];
+		crc &= 0xff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
-		tbl_idx = crc ^ *d;
-		crc = crc8_1wire_table[tbl_idx] & 0xff;
+		tbl_idx = (crc ^ *d) & 0xff;
+		crc = (crc8_table[0][tbl_idx]) & 0xff;
 		d++;
 	}
 
diff --git a/ext/digest/crc8/extconf.rb b/ext/digest/crc8/extconf.rb
index 1be8492..1c624a5 100644
--- a/ext/digest/crc8/extconf.rb
+++ b/ext/digest/crc8/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc8_table.h", "crc8_table", 8, 0x07, false)
+
 create_header
 create_makefile "crc8_ext"
diff --git a/ext/digest/crc8_1wire/crc8_1wire.c b/ext/digest/crc8_1wire/crc8_1wire.c
index 51ed75a..9e9f052 100644
--- a/ext/digest/crc8_1wire/crc8_1wire.c
+++ b/ext/digest/crc8_1wire/crc8_1wire.c
@@ -15,38 +15,42 @@
  */
 
 #include "crc8_1wire.h"
+#include "extconf.h"
 
-/**
- * Static table used for the table_driven implementation.
- */
-static const crc8_t crc8_table[256] = {
-	0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83, 0xc2, 0x9c, 0x7e, 0x20, 0xa3, 0xfd, 0x1f, 0x41,
-	0x9d, 0xc3, 0x21, 0x7f, 0xfc, 0xa2, 0x40, 0x1e, 0x5f, 0x01, 0xe3, 0xbd, 0x3e, 0x60, 0x82, 0xdc,
-	0x23, 0x7d, 0x9f, 0xc1, 0x42, 0x1c, 0xfe, 0xa0, 0xe1, 0xbf, 0x5d, 0x03, 0x80, 0xde, 0x3c, 0x62,
-	0xbe, 0xe0, 0x02, 0x5c, 0xdf, 0x81, 0x63, 0x3d, 0x7c, 0x22, 0xc0, 0x9e, 0x1d, 0x43, 0xa1, 0xff,
-	0x46, 0x18, 0xfa, 0xa4, 0x27, 0x79, 0x9b, 0xc5, 0x84, 0xda, 0x38, 0x66, 0xe5, 0xbb, 0x59, 0x07,
-	0xdb, 0x85, 0x67, 0x39, 0xba, 0xe4, 0x06, 0x58, 0x19, 0x47, 0xa5, 0xfb, 0x78, 0x26, 0xc4, 0x9a,
-	0x65, 0x3b, 0xd9, 0x87, 0x04, 0x5a, 0xb8, 0xe6, 0xa7, 0xf9, 0x1b, 0x45, 0xc6, 0x98, 0x7a, 0x24,
-	0xf8, 0xa6, 0x44, 0x1a, 0x99, 0xc7, 0x25, 0x7b, 0x3a, 0x64, 0x86, 0xd8, 0x5b, 0x05, 0xe7, 0xb9,
-	0x8c, 0xd2, 0x30, 0x6e, 0xed, 0xb3, 0x51, 0x0f, 0x4e, 0x10, 0xf2, 0xac, 0x2f, 0x71, 0x93, 0xcd,
-	0x11, 0x4f, 0xad, 0xf3, 0x70, 0x2e, 0xcc, 0x92, 0xd3, 0x8d, 0x6f, 0x31, 0xb2, 0xec, 0x0e, 0x50,
-	0xaf, 0xf1, 0x13, 0x4d, 0xce, 0x90, 0x72, 0x2c, 0x6d, 0x33, 0xd1, 0x8f, 0x0c, 0x52, 0xb0, 0xee,
-	0x32, 0x6c, 0x8e, 0xd0, 0x53, 0x0d, 0xef, 0xb1, 0xf0, 0xae, 0x4c, 0x12, 0x91, 0xcf, 0x2d, 0x73,
-	0xca, 0x94, 0x76, 0x28, 0xab, 0xf5, 0x17, 0x49, 0x08, 0x56, 0xb4, 0xea, 0x69, 0x37, 0xd5, 0x8b,
-	0x57, 0x09, 0xeb, 0xb5, 0x36, 0x68, 0x8a, 0xd4, 0x95, 0xcb, 0x29, 0x77, 0xf4, 0xaa, 0x48, 0x16,
-	0xe9, 0xb7, 0x55, 0x0b, 0x88, 0xd6, 0x34, 0x6a, 0x2b, 0x75, 0x97, 0xc9, 0x4a, 0x14, 0xf6, 0xa8,
-	0x74, 0x2a, 0xc8, 0x96, 0x15, 0x4b, 0xa9, 0xf7, 0xb6, 0xe8, 0x0a, 0x54, 0xd7, 0x89, 0x6b, 0x35
-};
+// This file is generated by generate_table in extconf.rb
+#include "crc8_1wire_table.h"
 
 crc8_t crc8_1wire_update(crc8_t crc, const void *data, size_t data_len)
 {
 	const unsigned char *d = (const unsigned char *)data;
 	unsigned int tbl_idx;
 
+	for (; data_len >= SLICE_SIZE; data_len -= SLICE_SIZE)
+	{
+		crc = crc8_1wire_table[15][d[ 0] ^ crc] ^
+		      crc8_1wire_table[14][d[ 1]      ] ^
+		      crc8_1wire_table[13][d[ 2]      ] ^
+		      crc8_1wire_table[12][d[ 3]      ] ^
+		      crc8_1wire_table[11][d[ 4]      ] ^
+		      crc8_1wire_table[10][d[ 5]      ] ^
+		      crc8_1wire_table[ 9][d[ 6]      ] ^
+		      crc8_1wire_table[ 8][d[ 7]      ] ^
+		      crc8_1wire_table[ 7][d[ 8]      ] ^
+		      crc8_1wire_table[ 6][d[ 9]      ] ^
+		      crc8_1wire_table[ 5][d[10]      ] ^
+		      crc8_1wire_table[ 4][d[11]      ] ^
+		      crc8_1wire_table[ 3][d[12]      ] ^
+		      crc8_1wire_table[ 2][d[13]      ] ^
+		      crc8_1wire_table[ 1][d[14]      ] ^
+		      crc8_1wire_table[ 0][d[15]      ];
+		crc &= 0xff;
+		d += SLICE_SIZE;
+	}
+
 	while (data_len--)
 	{
-		tbl_idx = crc ^ *d;
-		crc = (crc8_table[tbl_idx] ^ (crc >> 8)) & 0xff;
+		tbl_idx = (crc ^ *d) & 0xff;
+		crc = (crc8_1wire_table[0][tbl_idx]) & 0xff;
 		d++;
 	}
 
diff --git a/ext/digest/crc8_1wire/extconf.rb b/ext/digest/crc8_1wire/extconf.rb
index 8b45a79..c13a28f 100644
--- a/ext/digest/crc8_1wire/extconf.rb
+++ b/ext/digest/crc8_1wire/extconf.rb
@@ -1,7 +1,10 @@
 require 'mkmf'
+require_relative '../gentable'
 
 have_header("stdint.h")
 have_header('stddef.h')
 
+generate_table("crc8_1wire_table.h", "crc8_1wire_table", 8, 0x31, true)
+
 create_header
 create_makefile "crc8_1wire_ext"
diff --git a/ext/digest/gentable.rb b/ext/digest/gentable.rb
new file mode 100644
index 0000000..28afd1e
--- /dev/null
+++ b/ext/digest/gentable.rb
@@ -0,0 +1,105 @@
+require "erb"
+
+class Integer
+  def bitreflect(bits)
+    dest = 0
+    src  = self
+
+    bits.times {
+      dest = (dest << 1) | src[0]
+      src >>= 1
+    }
+
+    dest
+  end
+end
+
+def generate_table(path, table_name, bitwidth, polynomial, reflect_input)
+  raise "wrong polynomial (expect odd number, but given #{polynomial})" unless polynomial.odd?
+
+  slice_size = 16
+
+  case
+  when bitwidth < 1 || bitwidth > 64
+    raise "wrong bitwidth (expect 1..64, but given #{bitwidth})"
+  when bitwidth <= 8
+    bitclass = 8
+  when bitwidth <= 16
+    bitclass = 16
+  when bitwidth <= 32
+    bitclass = 32
+  else # bitwidth <= 64
+    bitclass = 64
+  end
+
+  # If the bit input is NORMAL, reverse the bit direction after performing
+  # the same table generation method as REFLECT.  This is because this
+  # eliminates the need to consider the alignment of the upper bits.
+
+  modified_poly = polynomial.bitreflect(bitwidth)
+
+  table0 = 256.times.map { |i|
+    8.times {
+      if i[0].zero?
+        i = (i >> 1)
+      else
+        i = (i >> 1) ^ modified_poly
+      end
+    }
+
+    i
+  }
+
+  table = [table0]
+
+  (1...slice_size).each do |s|
+    table_prev = table[s - 1]
+
+    table << 256.times.map { |i|
+      e = table_prev[i]
+      ((e >> 8) ^ table0[0xff & e])
+    }
+  end
+
+  unless reflect_input
+    table.map! { |t|
+      256.times.map { |i|
+        idx = i.bitreflect(8)
+        t[idx].bitreflect(bitwidth)
+      }
+    }
+  end
+
+  crcint    = "uint#{bitclass}_t"
+  step      = bitclass > 16 ? 4 : 8
+  generator = File.basename(__FILE__)
+  template  = ERB.new(<<~"CRC_TABLE.H", trim_mode: "%").tap { |erb| erb.lineno = __LINE__ }
+    /*
+     * bitwidth: <%= bitwidth %>
+     * generator polynomial: <%= "0x%0*x" % [bitclass / 4, polynomial] %>
+     * input bit direction: <%= reflect_input ? "REFLECT" : "NORMAL" %>
+     * slice bytes per iteration: <%= slice_size %>
+     * slide bits per table: 8
+     *
+     * Licensed under: Creative Commons Zero License (CC0; https://creativecommons.org/publicdomain/zero/1.0/)
+     * Generated by: <%= generator %> of digest-crc
+     */
+
+    #define SLICE_SIZE <%= slice_size %>
+
+    static const <%= crcint %> <%= table_name %>[SLICE_SIZE][256] = {
+    % slice_size.times.map { |s|
+    \t{
+    %   (0...256).step(step) { |ibase|
+    \t\t<%= step.times.map { |i| "0x%0*x" % [bitclass / 4, table[s][ibase + i]] }.join(", ") %>,
+    %   }
+    \t},
+    % }
+    };
+  CRC_TABLE.H
+  template.filename = __FILE__
+
+  File.binwrite(path, template.result(binding))
+
+  slice_size
+end
diff --git a/spec/crc15_spec.rb b/spec/crc15_spec.rb
index 355fe80..ff04f92 100644
--- a/spec/crc15_spec.rb
+++ b/spec/crc15_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc15'
 
 describe Digest::CRC15 do
-  let(:string)   { '1234567890' }
-  let(:expected) { '178c' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '38d0' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_ccitt_spec.rb b/spec/crc16_ccitt_spec.rb
index 8338514..73438a6 100644
--- a/spec/crc16_ccitt_spec.rb
+++ b/spec/crc16_ccitt_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_ccitt'
 
 describe Digest::CRC16CCITT do
-  let(:string)   { '1234567890' }
-  let(:expected) { '3218' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '20c8' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_genibus_spec.rb b/spec/crc16_genibus_spec.rb
index 55206c2..de47838 100644
--- a/spec/crc16_genibus_spec.rb
+++ b/spec/crc16_genibus_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_genibus'
 
 describe Digest::CRC16Genibus do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'cde7' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { 'df37' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_kermit_spec.rb b/spec/crc16_kermit_spec.rb
index 6e9e86e..c23edb8 100644
--- a/spec/crc16_kermit_spec.rb
+++ b/spec/crc16_kermit_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_kermit'
 
 describe Digest::CRC16Kermit do
-  let(:string)   { '1234567890' }
-  let(:expected) { '286b' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '0252' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_modbus_spec.rb b/spec/crc16_modbus_spec.rb
index 5ad16f1..3eaaa11 100644
--- a/spec/crc16_modbus_spec.rb
+++ b/spec/crc16_modbus_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_modbus'
 
 describe Digest::CRC16Modbus do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'c20a' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '92ce' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_spec.rb b/spec/crc16_spec.rb
index 3e49775..d3bdfcf 100644
--- a/spec/crc16_spec.rb
+++ b/spec/crc16_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16'
 
 describe Digest::CRC16 do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'c57a' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { 'b6ea' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_usb_spec.rb b/spec/crc16_usb_spec.rb
index 5b99303..c743cf8 100644
--- a/spec/crc16_usb_spec.rb
+++ b/spec/crc16_usb_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_usb'
 
 describe Digest::CRC16USB do
-  let(:string)   { '1234567890' }
-  let(:expected) { '3df5' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '6d31' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_x_25_spec.rb b/spec/crc16_x_25_spec.rb
index 1cdc688..28be74a 100644
--- a/spec/crc16_x_25_spec.rb
+++ b/spec/crc16_x_25_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_x_25'
 
 describe Digest::CRC16X25 do
-  let(:string)   { '1234567890' }
-  let(:expected) { '4b13' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '7b60' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_xmodem_spec.rb b/spec/crc16_xmodem_spec.rb
index dc36a67..22a25bd 100644
--- a/spec/crc16_xmodem_spec.rb
+++ b/spec/crc16_xmodem_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_xmodem'
 
 describe Digest::CRC16XModem do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'd321' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '93a9' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc16_zmodem_spec.rb b/spec/crc16_zmodem_spec.rb
index 67ee526..1b56bb1 100644
--- a/spec/crc16_zmodem_spec.rb
+++ b/spec/crc16_zmodem_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc16_zmodem'
 
 describe Digest::CRC16ZModem do
-  let(:string) { '1234567890' }
-  let(:expected) { 'd321' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { '93a9' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc1_spec.rb b/spec/crc1_spec.rb
index d79afd1..cbed80e 100644
--- a/spec/crc1_spec.rb
+++ b/spec/crc1_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc1'
 
 describe Digest::CRC1 do
-  let(:string) { '1234567890' }
-  let(:expected) { '0d' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { 'ea' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc24_spec.rb b/spec/crc24_spec.rb
index ccfcc91..34e52cd 100644
--- a/spec/crc24_spec.rb
+++ b/spec/crc24_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc24'
 
 describe Digest::CRC24 do
-  let(:string) { '1234567890' }
-  let(:expected) { '8c0072' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { 'e4bcb9' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32_bzip2_spec.rb b/spec/crc32_bzip2_spec.rb
index 58f0df0..5383264 100644
--- a/spec/crc32_bzip2_spec.rb
+++ b/spec/crc32_bzip2_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32_bzip2'
 
 describe Digest::CRC32BZip2 do
-  let(:string) { '1234567890' }
-  let(:expected) { '506853b6' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { '32ffa6d7' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32_jam_spec.rb b/spec/crc32_jam_spec.rb
index a52da2c..c5732f6 100644
--- a/spec/crc32_jam_spec.rb
+++ b/spec/crc32_jam_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32_jam'
 
 describe Digest::CRC32Jam do
-  let(:string) { '1234567890' }
-  let(:expected) { 'd9e2511a' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { '2c91ece6' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32_mpeg_spec.rb b/spec/crc32_mpeg_spec.rb
index 0b8c6e4..adbfe68 100644
--- a/spec/crc32_mpeg_spec.rb
+++ b/spec/crc32_mpeg_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32_mpeg'
 
 describe Digest::CRC32MPEG do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'af97ac49' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { 'cd005928' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32_posix_spec.rb b/spec/crc32_posix_spec.rb
index df62e6e..e6100e3 100644
--- a/spec/crc32_posix_spec.rb
+++ b/spec/crc32_posix_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32_posix'
 
 describe Digest::CRC32POSIX do
-  let(:string) { '1234567890' }
-  let(:expected) { 'c181fd8e' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { '3b934973' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32_spec.rb b/spec/crc32_spec.rb
index 0e000ab..aea8415 100644
--- a/spec/crc32_spec.rb
+++ b/spec/crc32_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32'
 
 describe Digest::CRC32 do
-  let(:string) { '1234567890' }
-  let(:expected) { '261daee5' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { 'd36e1319' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32_xfer_spec.rb b/spec/crc32_xfer_spec.rb
index c2a93e0..a9793a7 100644
--- a/spec/crc32_xfer_spec.rb
+++ b/spec/crc32_xfer_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32_xfer'
 
 describe Digest::CRC32XFER do
-  let(:string) { '1234567890' }
-  let(:expected) { '0be368eb' }
+  let(:string) { '1234567890123456789' }
+  let(:expected) { 'a7326a3b' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc32c_spec.rb b/spec/crc32c_spec.rb
index 580098b..adb9a95 100644
--- a/spec/crc32c_spec.rb
+++ b/spec/crc32c_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc32c'
 
 describe Digest::CRC32c do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'f3dbd4fe' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '8d155cb9' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc5_spec.rb b/spec/crc5_spec.rb
index 80d0171..470084a 100644
--- a/spec/crc5_spec.rb
+++ b/spec/crc5_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc5'
 
 describe Digest::CRC5 do
-  let(:string)   { '1234567890' }
-  let(:expected) { '01' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '0e' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc64_jones_spec.rb b/spec/crc64_jones_spec.rb
index 03e7c1b..469424e 100644
--- a/spec/crc64_jones_spec.rb
+++ b/spec/crc64_jones_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc64_jones'
 
 describe Digest::CRC64Jones do
-  let(:string)   { '1234567890' }
-  let(:expected) { '68a745ba133af9bd' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { 'c5b27dfe868bb180' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc64_spec.rb b/spec/crc64_spec.rb
index 54c75a7..224a596 100644
--- a/spec/crc64_spec.rb
+++ b/spec/crc64_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc64'
 
 describe Digest::CRC64 do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'bc66a5a9388a5bef' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { 'e6c8b671184bb966' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc64_xz_spec.rb b/spec/crc64_xz_spec.rb
index 7a9a0c0..468d1fb 100644
--- a/spec/crc64_xz_spec.rb
+++ b/spec/crc64_xz_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc64_xz'
 
 describe Digest::CRC64XZ do
-  let(:string)   { '1234567890' }
-  let(:expected) { 'b1cb31bbb4a2b2be' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '6eecc5f3f4c26bd9' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc8_1wire_spec.rb b/spec/crc8_1wire_spec.rb
index 17c1bf4..1f9ff90 100644
--- a/spec/crc8_1wire_spec.rb
+++ b/spec/crc8_1wire_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc8_1wire'
 
 describe Digest::CRC8_1Wire do
-  let(:string)   { '1234567890' }
-  let(:expected) { '4f' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '71' }
 
   it_should_behave_like "CRC"
 end
diff --git a/spec/crc8_spec.rb b/spec/crc8_spec.rb
index de33f34..00396f7 100644
--- a/spec/crc8_spec.rb
+++ b/spec/crc8_spec.rb
@@ -3,8 +3,8 @@
 require 'digest/crc8'
 
 describe Digest::CRC8 do
-  let(:string)   { '1234567890' }
-  let(:expected) { '52' }
+  let(:string)   { '1234567890123456789' }
+  let(:expected) { '99' }
 
   it_should_behave_like "CRC"
 end