#include "crc16.h"
#define CRC16_POLY_CCITT 0x1021
#define CRC16_POLY 0x8408
-#define CRC16_POLY_LEGIC 0xB400
-unsigned short update_crc16( unsigned short crc, unsigned char c )
-{
- unsigned short i, v, tcrc = 0;
+uint16_t update_crc16( uint16_t crc, unsigned char c ) {
+ uint16_t i, v, tcrc = 0;
v = (crc ^ c) & 0xff;
for (i = 0; i < 8; i++) {
if (length == 0)
return (~remainder);
- for (int byte = 0; byte < length; ++byte) {
- remainder ^= (message[byte] << 8);
+ for (uint32_t i = 0; i < length; ++i) {
+ remainder ^= (message[i] << 8);
for (uint8_t bit = 8; bit > 0; --bit) {
if (remainder & 0x8000) {
remainder = (remainder << 1) ^ polynomial;
}
uint16_t crc16_ccitt_kermit(uint8_t const *message, int length) {
- return bit_reverse_uint16(crc16(message, length, 0x0000, CRC16_POLY_CCITT));
-}
-
-//ICEMAN: not working yet,
-// This CRC-16 is used in Legic Advant systems.
-uint16_t crc16_legic(uint8_t const *message, int length, uint16_t inital) {
- return crc16(message, length, inital, CRC16_POLY_LEGIC);
-}
-
-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;
+ uint16_t val = crc16(message, length, 0x0000, CRC16_POLY_CCITT);
+ return SwapBits(val, 16);
}