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CHG: merged the forum user @jason 's fixes to LEGIC. *UNTESTED*

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CHG: changed the CRC implementations.
This commit is contained in:
iceman1001 2016-07-28 21:41:44 +02:00
commit 3e134b4c20
16 changed files with 1368 additions and 163 deletions
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33
common/crc16.c
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@ -9,11 +9,9 @@
#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++) {
@ -29,8 +27,8 @@ uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t
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;
@ -47,25 +45,6 @@ uint16_t crc16_ccitt(uint8_t const *message, int length) {
}
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);
}