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dxt.c
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#define HL_NAME(n) heaps_##n
#include <hl.h>
static const int BIT5[] = { 0, 8, 16, 25, 33, 41, 49, 58, 66, 74, 82, 90, 99, 107, 115, 123, 132, 140, 148, 156, 165, 173, 181, 189, 197, 206, 214, 222, 230, 239, 247, 255 };
static const int BIT6[] = { 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 130, 134, 138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190, 194, 198, 202, 206, 210, 215, 219, 223, 227, 231, 235, 239, 243, 247, 251, 255 };
#define MK_COLOR(r,g,b,a) (((a)<<24) | ((b)<<16) | ((g)<<8) | (r))
#define DXT_COLOR1(c,a) MK_COLOR( \
BIT5[(c & 0xFC00) >> 11], \
BIT6[(c & 0x07E0) >> 5], \
BIT5[(c & 0x001F)], \
a)
#define DXT_COLOR2(c0,c1,a) MK_COLOR( \
(BIT5[(c0 & 0xFC00) >> 11] + BIT5[(c1 & 0xFC00) >> 11]) / 2, \
(BIT6[(c0 & 0x07E0) >> 5] + BIT6[(c1 & 0x07E0) >> 5]) / 2, \
(BIT5[c0 & 0x001F] + BIT5[c1 & 0x001F]) / 2, \
a)
#define DXT_COLOR3(c0,c1,a) MK_COLOR( \
(2 * BIT5[(c0 & 0xFC00) >> 11] + BIT5[(c1 & 0xFC00) >> 11]) / 3, \
(2 * BIT6[(c0 & 0x07E0) >> 5] + BIT6[(c1 & 0x07E0) >> 5]) / 3, \
(2 * BIT5[c0 & 0x001F] + BIT5[c1 & 0x001F]) / 3, \
a)
static int dxtAlpha(int a0, int a1, int t) {
if (a0 > a1) switch (t) {
case 0: return a0;
case 1: return a1;
case 2: return (6 * a0 + a1) / 7;
case 3: return (5 * a0 + 2 * a1) / 7;
case 4: return (4 * a0 + 3 * a1) / 7;
case 5: return (3 * a0 + 4 * a1) / 7;
case 6: return (2 * a0 + 5 * a1) / 7;
case 7: return (a0 + 6 * a1) / 7;
}
else switch (t) {
case 0: return a0;
case 1: return a1;
case 2: return (4 * a0 + a1) / 5;
case 3: return (3 * a0 + 2 * a1) / 5;
case 4: return (2 * a0 + 3 * a1) / 5;
case 5: return (a0 + 4 * a1) / 5;
case 6: return 0;
case 7: return 255;
}
return 0;
}
static int dxtColor(int c0, int c1, int a, int t) {
switch (t) {
case 0: return DXT_COLOR1(c0, a);
case 1: return DXT_COLOR1(c1, a);
case 2: return (c0 > c1) ? DXT_COLOR3(c0, c1, a) : DXT_COLOR2(c0, c1, a);
case 3: return (c0 > c1) ? DXT_COLOR3(c1, c0, a) : 0;
}
return 0;
}
HL_PRIM bool HL_NAME(dxt_decode)( vbyte *data, int *out, int width, int height, int format ) {
int x,y,k;
int index = 0;
int write = 0;
int alpha[16];
switch( format ) {
case 1:
for(y=0;y<height>>2;y++) {
for(x=0;x<width>>2;x++) {
int c0 = data[index] | (data[index + 1] << 8); index += 2;
int c1 = data[index] | (data[index + 1] << 8); index += 2;
for(k=0;k<4;k++) {
unsigned char c = data[index++];
int t0 = c & 0x03;
int t1 = (c & 0x0C) >> 2;
int t2 = (c & 0x30) >> 4;
int t3 = (c & 0xC0) >> 6;
int w = write + k * width;
out[w++] = dxtColor(c0, c1, 0xFF, t0);
out[w++] = dxtColor(c0, c1, 0xFF, t1);
out[w++] = dxtColor(c0, c1, 0xFF, t2);
out[w++] = dxtColor(c0, c1, 0xFF, t3);
}
write += 4;
}
write += 3 * width;
}
return true;
case 2:
for(y=0;y<height>>2;y++) {
for(x=0;x<width>>2;x++) {
int ap = 0;
for(k=0;k<4;k++) {
int a0 = data[index++];
int a1 = data[index++];
alpha[ap++] = 17 * ((a0 & 0xF0) >> 4);
alpha[ap++] = 17 * (a0 & 0x0F);
alpha[ap++] = 17 * ((a1 & 0xF0) >> 4);
alpha[ap++] = 17 * (a1 & 0x0F);
}
ap = 0;
int c0 = data[index] | (data[index + 1] << 8); index += 2;
int c1 = data[index] | (data[index + 1] << 8); index += 2;
for (int k = 0; k<4; k++) {
int c = data[index++];
int t0 = c & 0x03;
int t1 = (c & 0x0C) >> 2;
int t2 = (c & 0x30) >> 4;
int t3 = (c & 0xC0) >> 6;
int w = write + k * width;
out[w++] = dxtColor(c0, c1, alpha[ap++], t0);
out[w++] = dxtColor(c0, c1, alpha[ap++], t1);
out[w++] = dxtColor(c0, c1, alpha[ap++], t2);
out[w++] = dxtColor(c0, c1, alpha[ap++], t3);
}
write += 4;
}
write += 3 * width;
}
return true;
case 3:
for(y=0;y<height>>2;y++) {
for(x=0;x<width>>2;x++) {
int a0 = data[index++];
int a1 = data[index++];
int b0 = data[index] | (data[index + 1] << 8) | (data[index + 2] << 16); index += 3;
int b1 = data[index] | (data[index + 1] << 8) | (data[index + 2] << 16); index += 3;
alpha[0] = b0 & 0x07;
alpha[1] = (b0 >> 3) & 0x07;
alpha[2] = (b0 >> 6) & 0x07;
alpha[3] = (b0 >> 9) & 0x07;
alpha[4] = (b0 >> 12) & 0x07;
alpha[5] = (b0 >> 15) & 0x07;
alpha[6] = (b0 >> 18) & 0x07;
alpha[7] = (b0 >> 21) & 0x07;
alpha[8] = b1 & 0x07;
alpha[9] = (b1 >> 3) & 0x07;
alpha[10] = (b1 >> 6) & 0x07;
alpha[11] = (b1 >> 9) & 0x07;
alpha[12] = (b1 >> 12) & 0x07;
alpha[13] = (b1 >> 15) & 0x07;
alpha[14] = (b1 >> 18) & 0x07;
alpha[15] = (b1 >> 21) & 0x07;
int c0 = data[index] | (data[index + 1] << 8); index += 2;
int c1 = data[index] | (data[index + 1] << 8); index += 2;
int ap = 0;
for (int k = 0; k<4; k++) {
int c = data[index++];
int t0 = c & 0x03;
int t1 = (c & 0x0C) >> 2;
int t2 = (c & 0x30) >> 4;
int t3 = (c & 0xC0) >> 6;
int w = write + k * width;
out[w++] = dxtColor(c0, c1, dxtAlpha(a0, a1, alpha[ap++]), t0);
out[w++] = dxtColor(c0, c1, dxtAlpha(a0, a1, alpha[ap++]), t1);
out[w++] = dxtColor(c0, c1, dxtAlpha(a0, a1, alpha[ap++]), t2);
out[w++] = dxtColor(c0, c1, dxtAlpha(a0, a1, alpha[ap++]), t3);
}
write += 4;
}
write += 3 * width;
}
return true;
default:
return false;
}
}
DEFINE_PRIM(_BOOL, dxt_decode, _BYTES _BYTES _I32 _I32 _I32);