- return crc16(message, length, 0xffff, 0x1021);
+ return crc16(message, length, 0xffff, 0x1021);
+}
+
+uint16_t crc16_ccitt_kermit(uint8_t const *message, int length) {
+ return bit_reverse_uint16(crc16(message, length, 0x0000, 0x1021));
+}
+
+uint16_t bit_reverse_uint16 (uint16_t value) {
+ const uint16_t mask0 = 0x5555;
+ const uint16_t mask1 = 0x3333;
+ const uint16_t mask2 = 0x0F0F;
+ const uint16_t mask3 = 0x00FF;
+
+ value = (((~mask0) & value) >> 1) | ((mask0 & value) << 1);
+ value = (((~mask1) & value) >> 2) | ((mask1 & value) << 2);
+ value = (((~mask2) & value) >> 4) | ((mask2 & value) << 4);
+ value = (((~mask3) & value) >> 8) | ((mask3 & value) << 8);
+
+ return value;