Now builds on avr-gcc 5.4.0.

light_ws2812_AVR/Light_WS2812/light_ws2812.c

@@ -124,6 +124,7 @@ void ws2812_sendarray(uint8_t *data,uint16_t datlen)
 
 void inline ws2812_sendarray_mask(uint8_t *data,uint16_t datlen,uint8_t maskhi)
 {
+  // `maskhi` is 0x80 if P?7 is the DATA line to the LED string, 0x04 for P?2 etc.
   uint8_t curbyte,ctr,masklo;
   uint8_t sreg_prev;
 #if __AVR_ARCH__ != 100  
@@ -133,17 +134,30 @@ void inline ws2812_sendarray_mask(uint8_t *data,uint16_t datlen,uint8_t maskhi)
   ws2812_DDRREG |= maskhi; // Enable output
 
   masklo	=~maskhi&ws2812_PORTREG;
+  // `masklo` becomes the value to write to the PORT? register in order to
+  // drive the DATA line low.
   maskhi |=        ws2812_PORTREG;
+  // `maskhi` becomes the value to write to the PORT? register in order to
+  // drive the DATA line high.  All other bits in the PORT? register are
+  // preserved by becoming part of the byte that is written here.
 
   sreg_prev=SREG;
+
+  // If we are not expected to support interrupts while driving the LED
+  // string..
 #ifdef interrupt_is_disabled
   cli();  
 #endif  
 
+  // Go through each byte that should be sent to the LED string..
   while (datlen--) {
     curbyte=*data++;
 
+#ifndef __GNUC__
     asm volatile(
+#else
+    __asm__ volatile(
+#endif
     "       ldi   %0,8  \n\t"
 #ifndef interrupt_is_disabled
     "       clt         \n\t"