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fix: 'crc iclass' doesn't need byteswapping

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This commit is contained in:
iceman1001 2018-02-01 09:33:34 +01:00
parent 721ba5d287
commit bcf6fcd193
1 changed files with 10 additions and 3 deletions
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13
common/crc16.c
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@ -147,6 +147,12 @@ uint16_t crc16(uint8_t const *d, size_t length, uint16_t remainder, uint16_t pol
}
void compute_crc(CrcType_t ct, const uint8_t *d, size_t n, uint8_t *first, uint8_t *second) {
// can't calc a crc on less than 3 byte. (1byte + 2 crc bytes)
if ( n < 3 ) return;
init_table(ct);
uint16_t crc = 0;
switch (ct) {
case CRC_14A: crc = crc16_a(d, n); break;
@ -167,10 +173,13 @@ void compute_crc(CrcType_t ct, const uint8_t *d, size_t n, uint8_t *first, uint8
uint16_t crc16_ccitt(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0xffff, false, false);
}
// FDX-B ISO11784/85) uses KERMIT
//poly=0x1021 init=0x0000 refin=true refout=true xorout=0x0000 name="KERMIT"
uint16_t crc16_kermit(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0x0000, true, true);
}
// FeliCa uses XMODEM
//poly=0x1021 init=0x0000 refin=false refout=false xorout=0x0000 name="XMODEM"
uint16_t crc16_xmodem(uint8_t const *d, size_t n) {
@ -198,14 +207,12 @@ uint16_t crc16_a(uint8_t const *d, size_t n) {
// poly 0x1021 reflected 0x8408
// poly=0x1021 init=0x4807 refin=true refout=true xorout=0x0BC3 check=0xF0B8 name="CRC-16/ICLASS"
uint16_t crc16_iclass(uint8_t const *d, size_t n) {
return BSWAP_16(crc16_fast(d, n, 0x4807, true, true));
return crc16_fast(d, n, 0x4807, true, true);
}
// This CRC-16 is used in Legic Advant systems.
// poly=0xB400, init=depends refin=true refout=true xorout=0x0000 check= name="CRC-16/LEGIC"
uint16_t crc16_legic(uint8_t const *d, size_t n, uint8_t uidcrc) {
//uint16_t initial = reflect8(uidcrc);
//initial |= initial << 8;
uint16_t initial = uidcrc << 8 | uidcrc;
return crc16_fast(d, n, initial, true, true);
}