mirror of
https://github.com/RfidResearchGroup/proxmark3.git
synced 2024-09-20 15:26:13 +08:00
267 lines
7.2 KiB
C
267 lines
7.2 KiB
C
//-----------------------------------------------------------------------------
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// This code is licensed to you under the terms of the GNU GPL, version 2 or,
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// at your option, any later version. See the LICENSE.txt file for the text of
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// the license.
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//-----------------------------------------------------------------------------
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// CRC16
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//-----------------------------------------------------------------------------
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#include "crc16.h"
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static uint16_t crc_table[256];
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static bool crc_table_init = false;
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static CrcType_t crc_type = CRC_NONE;
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void init_table(CrcType_t ct) {
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// same crc algo, and initialised already
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if ( ct == crc_type && crc_table_init)
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return;
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// not the same crc algo. reset table.
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if ( ct != crc_type)
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reset_table();
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crc_type = ct;
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switch (ct) {
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case CRC_14443_A:
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case CRC_14443_B:
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case CRC_15693:
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case CRC_ICLASS: generate_table(CRC16_POLY_CCITT, true); break;
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case CRC_FELICA: generate_table(CRC16_POLY_CCITT, false); break;
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case CRC_LEGIC: generate_table(CRC16_POLY_LEGIC, true); break;
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case CRC_CCITT: generate_table(CRC16_POLY_CCITT, false); break;
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case CRC_KERMIT: generate_table(CRC16_POLY_CCITT, true); break;
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default:
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crc_table_init = false;
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crc_type = CRC_NONE;
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break;
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}
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}
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void generate_table( uint16_t polynomial, bool refin) {
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uint16_t i, j, crc, c;
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for (i = 0; i < 256; i++) {
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crc = 0;
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if (refin)
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c = reflect8(i) << 8;
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else
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c = i << 8;
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for (j = 0; j < 8; j++) {
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if ( (crc ^ c) & 0x8000 )
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crc = ( crc << 1 ) ^ polynomial;
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else
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crc = crc << 1;
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c = c << 1;
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}
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if (refin)
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crc = reflect16(crc);
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crc_table[i] = crc;
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}
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crc_table_init = true;
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}
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void reset_table(void) {
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memset(crc_table, 0, sizeof(crc_table));
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crc_table_init = false;
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crc_type = CRC_NONE;
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}
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// table lookup LUT solution
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uint16_t crc16_fast(uint8_t const *d, size_t n, uint16_t initval, bool refin, bool refout) {
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// fast lookup table algorithm without augmented zero bytes, e.g. used in pkzip.
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// only usable with polynom orders of 8, 16, 24 or 32.
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if (n == 0)
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return (~initval);
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uint16_t crc = initval;
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if (refin)
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crc = reflect16(crc);
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if (!refin)
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while (n--) crc = (crc << 8) ^ crc_table[ ((crc >> 8) ^ *d++) & 0xFF ];
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else
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while (n--) crc = (crc >> 8) ^ crc_table[ (crc & 0xFF) ^ *d++];
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if (refout^refin)
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crc = reflect16(crc);
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return crc;
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}
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// bit looped solution TODO REMOVED
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uint16_t update_crc16_ex( uint16_t crc, uint8_t c, uint16_t polynomial ) {
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uint16_t i, v, tmp = 0;
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v = (crc ^ c) & 0xff;
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for (i = 0; i < 8; i++) {
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if ( (tmp ^ v) & 1 )
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tmp = ( tmp >> 1 ) ^ polynomial;
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else
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tmp >>= 1;
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v >>= 1;
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}
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return ((crc >> 8) ^ tmp) & 0xffff;
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}
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uint16_t update_crc16( uint16_t crc, uint8_t c ) {
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return update_crc16_ex( crc, c, CRC16_POLY_CCITT);
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}
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// two ways. msb or lsb loop.
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uint16_t crc16(uint8_t const *d, size_t length, uint16_t remainder, uint16_t polynomial, bool refin, bool refout) {
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if (length == 0)
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return (~remainder);
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uint8_t c;
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for (uint32_t i = 0; i < length; ++i) {
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c = d[i];
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if (refin) c = reflect8(c);
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// xor in at msb
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remainder ^= (c << 8);
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// 8 iteration loop
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for (uint8_t j = 8; j; --j) {
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if (remainder & 0x8000) {
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remainder = (remainder << 1) ^ polynomial;
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} else {
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remainder <<= 1;
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}
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}
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}
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if (refout)
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remainder = reflect16(remainder);
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return remainder;
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}
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void compute_crc(CrcType_t ct, const uint8_t *d, size_t n, uint8_t *first, uint8_t *second) {
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// can't calc a crc on less than 1 byte
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if ( n == 0 ) return;
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init_table(ct);
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uint16_t crc = 0;
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switch (ct) {
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case CRC_14443_A: crc = crc16_a(d, n); break;
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case CRC_14443_B:
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case CRC_15693: crc = crc16_x25(d, n); break;
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case CRC_ICLASS: crc = crc16_iclass(d, n); break;
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case CRC_FELICA:crc = crc16_xmodem(d, n); break;
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//case CRC_LEGIC:
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case CRC_CCITT: crc = crc16_ccitt(d, n); break;
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case CRC_KERMIT: crc = crc16_kermit(d, n); break;
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default: break;
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}
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*first = (crc & 0xFF);
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*second = ((crc >> 8) & 0xFF);
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}
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uint16_t crc(CrcType_t ct, const uint8_t *d, size_t n) {
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// can't calc a crc on less than 3 byte. (1byte + 2 crc bytes)
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if ( n < 3 ) return 0;
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init_table(ct);
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switch (ct) {
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case CRC_14443_A: return crc16_a(d, n);
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case CRC_14443_B:
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case CRC_15693: return crc16_x25(d, n);
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case CRC_ICLASS: return crc16_iclass(d, n);
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case CRC_FELICA: return crc16_xmodem(d, n);
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//case CRC_LEGIC:
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case CRC_CCITT: return crc16_ccitt(d, n);
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case CRC_KERMIT: return crc16_kermit(d, n);
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default: break;
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}
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return 0;
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}
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// check CRC
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// ct crc type
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// d buffer with data
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// n length (including crc)
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//
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// This function uses the message + crc bytes in order to compare the "residue" afterwards.
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// crc16 algos like CRC-A become 0x000
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// while CRC-15693 become 0x0F47
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// If calculated with crc bytes, the residue should be 0xF0B8
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bool check_crc(CrcType_t ct, const uint8_t *d, size_t n) {
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// can't calc a crc on less than 3 byte. (1byte + 2 crc bytes)
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if ( n < 3 ) return false;
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init_table(ct);
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switch (ct) {
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case CRC_14443_A: return (crc16_a(d, n) == 0);
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case CRC_14443_B: return (crc16_x25(d, n) == X25_CRC_CHECK);
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case CRC_15693: return (crc16_x25(d, n) == X25_CRC_CHECK);
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case CRC_ICLASS: return (crc16_iclass(d, n) == 0);
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case CRC_FELICA: return (crc16_xmodem(d, n) == 0);
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//case CRC_LEGIC:
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case CRC_CCITT: return (crc16_ccitt(d, n) == 0);
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default: break;
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}
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return false;
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}
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// poly=0x1021 init=0xffff refin=false refout=false xorout=0x0000 check=0x29b1 residue=0x0000 name="CRC-16/CCITT-FALSE"
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uint16_t crc16_ccitt(uint8_t const *d, size_t n) {
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return crc16_fast(d, n, 0xffff, false, false);
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}
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// FDX-B ISO11784/85) uses KERMIT
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// poly=0x1021 init=0x0000 refin=true refout=true xorout=0x0000 name="KERMIT"
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uint16_t crc16_kermit(uint8_t const *d, size_t n) {
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return crc16_fast(d, n, 0x0000, true, true);
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}
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// FeliCa uses XMODEM
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// poly=0x1021 init=0x0000 refin=false refout=false xorout=0x0000 name="XMODEM"
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uint16_t crc16_xmodem(uint8_t const *d, size_t n) {
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return crc16_fast(d, n, 0x0000, false, false);
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}
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// Following standards uses X-25
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// ISO 15693,
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// ISO 14443 CRC-B
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// ISO/IEC 13239 (formerly ISO/IEC 3309)
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// poly=0x1021 init=0xffff refin=true refout=true xorout=0xffff name="X-25"
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uint16_t crc16_x25(uint8_t const *d, size_t n) {
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uint16_t crc = crc16_fast(d, n, 0xffff, true, true);
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crc = ~crc;
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return crc;
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}
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// CRC-A (14443-3)
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// poly=0x1021 init=0xc6c6 refin=true refout=true xorout=0x0000 name="CRC-A"
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uint16_t crc16_a(uint8_t const *d, size_t n) {
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return crc16_fast(d, n, 0xC6C6, true, true);
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}
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// iClass crc
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// initvalue 0x4807 reflected 0xE012
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// poly 0x1021 reflected 0x8408
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// poly=0x1021 init=0x4807 refin=true refout=true xorout=0x0BC3 check=0xF0B8 name="CRC-16/ICLASS"
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uint16_t crc16_iclass(uint8_t const *d, size_t n) {
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return crc16_fast(d, n, 0x4807, true, true);
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}
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// This CRC-16 is used in Legic Advant systems.
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// poly=0xB400, init=depends refin=true refout=true xorout=0x0000 check= name="CRC-16/LEGIC"
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uint16_t crc16_legic(uint8_t const *d, size_t n, uint8_t uidcrc) {
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uint16_t initial = uidcrc << 8 | uidcrc;
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return crc16_fast(d, n, initial, true, true);
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}
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