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Add CCITT Kermit CRC check for FDX-B demod

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This commit is contained in:
marshmellow42 2015-06-04 12:53:19 -04:00
commit 6eaa8da9dc
3 changed files with 51 additions and 26 deletions
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16
client/cmddata.c
View file

@ -23,6 +23,7 @@
#include "lfdemod.h"
#include "usb_cmd.h"
#include "crc.h"
#include "crc16.h"
uint8_t DemodBuffer[MAX_DEMOD_BUF_LEN];
uint8_t g_debugMode;
@ -1501,9 +1502,10 @@ int CmdFDXBdemodBI(const char *Cmd){
if (g_debugMode) {
char *bin = sprint_bin_break(BitStream,size,16);
PrintAndLog("DEBUG BinStream:\n%s",bin);
PrintAndLog("0x%s", sprint_hex(BitStream,16));
}
PrintAndLog("\nFDX-B / ISO 11784/5 Animal Tag ID Found:");
if (g_debugMode) PrintAndLog("startmarker %d; Size %d", preambleIndex, size);
if (g_debugMode) PrintAndLog("Start marker %d; Size %d", preambleIndex, size);
//return 1;
//got a good demod
@ -1515,14 +1517,22 @@ int CmdFDXBdemodBI(const char *Cmd){
uint32_t crc16 = bytebits_to_byteLSBF(BitStream+64,16);
uint32_t extended = bytebits_to_byteLSBF(BitStream+80,24);
uint64_t rawid = ((uint64_t)bytebits_to_byteLSBF(BitStream,32)<<32) | bytebits_to_byteLSBF(BitStream+32,32);
uint8_t raw[8];
num_to_bytes(rawid, 8, raw);
uint8_t *ID = SwapEndian64(raw, 8, 4);
if (g_debugMode) PrintAndLog("Raw ID Hex: %s", sprint_hex(ID,8));
uint16_t calcCrc = crc16_ccitt_kermit(ID, 8);
PrintAndLog("Animal ID: %u-%012llu", countryCode, NationalCode);
PrintAndLog("National Code: %012llu", NationalCode);
PrintAndLog("CountryCode: %u", countryCode);
PrintAndLog("Extended Data: %s", dataBlockBit ? "True" : "False");
PrintAndLog("reserved Code: %u", reservedCode);
PrintAndLog("Animal Tag: %s", animalBit ? "True" : "False");
PrintAndLog("CRC: 0x%02X", crc16);
PrintAndLog("Extended: 0x%X", extended);
PrintAndLog("CRC: 0x%04X - [%04X] - %s", crc16, calcCrc, (calcCrc == crc16) ? "Passed" : "Failed");
PrintAndLog("Extended: 0x%X\n", extended);
return 1;
}

56
common/crc16.c
View file

@ -11,35 +11,49 @@
unsigned short update_crc16( unsigned short crc, unsigned char c )
{
unsigned short i, v, tcrc = 0;
unsigned short i, v, tcrc = 0;
v = (crc ^ c) & 0xff;
for (i = 0; i < 8; i++) {
tcrc = ( (tcrc ^ v) & 1 ) ? ( tcrc >> 1 ) ^ 0x8408 : tcrc >> 1;
v >>= 1;
}
v = (crc ^ c) & 0xff;
for (i = 0; i < 8; i++) {
tcrc = ( (tcrc ^ v) & 1 ) ? ( tcrc >> 1 ) ^ 0x8408 : tcrc >> 1;
v >>= 1;
}
return ((crc >> 8) ^ tcrc)&0xffff;
return ((crc >> 8) ^ tcrc)&0xffff;
}
uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t polynomial) {
if (length == 0)
return (~remainder);
if (length == 0) return (~remainder);
for (int byte = 0; byte < length; ++byte) {
remainder ^= (message[byte] << 8);
for (uint8_t bit = 8; bit > 0; --bit) {
if (remainder & 0x8000) {
remainder = (remainder << 1) ^ polynomial;
} else {
remainder = (remainder << 1);
}
}
}
return remainder;
for (int byte = 0; byte < length; ++byte) {
remainder ^= (message[byte] << 8);
for (uint8_t bit = 8; bit > 0; --bit) {
if (remainder & 0x8000) {
remainder = (remainder << 1) ^ polynomial;
} else {
remainder = (remainder << 1);
}
}
}
return remainder;
}
uint16_t crc16_ccitt(uint8_t const *message, int length) {
return crc16(message, length, 0xffff, 0x1021);
return crc16(message, length, 0xffff, 0x1021);
}
uint16_t crc16_ccitt_kermit(uint8_t const *message, int length) {
if (length == 0) return 0;
uint32_t crc = 0, q = 0;
uint8_t c;
for (int i = 0; i < length; i++){
c = message[i];
q = (crc ^ c ) & 0xF;
crc = (crc >> 4) ^ (q * 0x1081);
q = (crc ^ (c >> 4)) & 0xF;
crc = (crc >> 4) ^ (q * 0x1081);
}
return crc;
}

1
common/crc16.h
View file

@ -12,4 +12,5 @@
unsigned short update_crc16(unsigned short crc, unsigned char c);
uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t polynomial);
uint16_t crc16_ccitt(uint8_t const *message, int length);
uint16_t crc16_ccitt_kermit(uint8_t const *message, int length);
#endif