git.zerfleddert.de Git - proxmark3-svn/blob - common/crc.c

   1 //-----------------------------------------------------------------------------
   2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   3 // at your option, any later version. See the LICENSE.txt file for the text of
   4 // the license.
   5 //-----------------------------------------------------------------------------
   6 // Generic CRC calculation code.
   7 //-----------------------------------------------------------------------------
   8 // the Check value below in the comments is CRC of the string '123456789'
   9 //
  10 #include "crc.h"
  11
  12 void crc_init_ref(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor, bool refin, bool refout) {
  13         crc_init(crc, order, polynom, initial_value, final_xor);
  14         crc->refin = refin;
  15         crc->refout = refout;
  16         crc_clear(crc);
  17 }
  18
  19 void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor) {
  20         crc->order = order;
  21         crc->topbit = BITMASK( order-1 );
  22         crc->polynom = polynom;
  23         crc->initial_value = initial_value;
  24         crc->final_xor = final_xor;
  25         crc->mask = (1L<<order)-1;
  26         crc->refin = FALSE;
  27         crc->refout = FALSE;
  28         crc_clear(crc);
  29 }
  30
  31 void crc_clear(crc_t *crc) {
  32         crc->state = crc->initial_value & crc->mask;
  33         if (crc->refin)
  34                 crc->state = reflect(crc->state, crc->order);
  35 }
  36
  37 void crc_update(crc_t *crc, uint32_t indata, int data_width){
  38
  39         //reflected
  40         if (crc->refin) indata = reflect(indata, data_width);
  41
  42         // Bring the next byte into the remainder.
  43         crc->state ^= indata << (crc->order - data_width);
  44
  45         for( uint8_t bit = data_width; bit > 0; --bit) {
  46                  // Try to divide the current data bit.
  47                 if (crc->state & crc->topbit)
  48                         crc->state = (crc->state << 1) ^ crc->polynom;
  49                 else
  50                         crc->state = (crc->state << 1);
  51         }
  52 }
  53
  54 uint32_t crc_finish(crc_t *crc) {
  55         uint32_t val = crc->state;
  56         if (crc->refout) val = reflect(val, crc->order);
  57         return ( val ^ crc->final_xor ) & crc->mask;
  58 }
  59
  60 /*
  61 static void print_crc(crc_t *crc) {
  62         printf(" Order  %d\n Poly   %x\n Init   %x\n Final  %x\n Mask   %x\n topbit %x\n RefIn  %s\n RefOut %s\n State  %x\n",
  63                 crc->order,
  64                 crc->polynom,
  65                 crc->initial_value,
  66                 crc->final_xor,
  67                 crc->mask,
  68                 crc->topbit,
  69                 (crc->refin) ? "TRUE":"FALSE",
  70                 (crc->refout) ? "TRUE":"FALSE",
  71                 crc->state
  72         );
  73 }
  74 */
  75
  76 // width=8  poly=0x31  init=0x00  refin=true  refout=true  xorout=0x00  check=0xA1  name="CRC-8/MAXIM"
  77 uint32_t CRC8Maxim(uint8_t *buff, size_t size) {
  78         crc_t crc;
  79         crc_init_ref(&crc, 8, 0x31, 0, 0, TRUE, TRUE);
  80         for ( int i=0; i < size; ++i)
  81                 crc_update(&crc, buff[i], 8);
  82         return crc_finish(&crc);
  83 }
  84
  85
  86 // width=4  poly=0xC, reversed poly=0x7  init=0x5   refin=true  refout=true  xorout=0x0000  check=  name="CRC-4/LEGIC"
  87 // width=8  poly=0x63, reversed poly=0x8D  init=0x55  refin=true  refout=true  xorout=0x0000  check=0xC6  name="CRC-8/LEGIC"
  88 // the CRC needs to be reversed before returned.
  89 uint32_t CRC8Legic(uint8_t *buff, size_t size) {
  90         crc_t crc;
  91         crc_init_ref(&crc, 8, 0x63, 0x55, 0, TRUE, TRUE);
  92         for ( int i = 0; i < size; ++i)
  93                 crc_update(&crc, buff[i], 8);
  94         return reflect(crc_finish(&crc), 8);
  95 }
  96
  97 // This CRC-16 is used in Legic Advant systems.
  98 // width=8  poly=0xB400, reversed poly=0x  init=depends  refin=true  refout=true  xorout=0x0000  check=  name="CRC-16/LEGIC"
  99 uint32_t CRC16Legic(uint8_t *buff, size_t size, uint8_t uidcrc) {
 100
 101         #define CRC16_POLY_LEGIC 0xB400
 102         uint16_t initial = reflect(uidcrc, 8);
 103         //uint16_t initial = uidcrc;
 104         initial |= initial << 8;
 105         crc_t crc;
 106         crc_init_ref(&crc, 16, CRC16_POLY_LEGIC, initial, 0, TRUE, TRUE);
 107         for ( int i=0; i < size; ++i)
 108                 crc_update(&crc, buff[i], 8);
 109         return reflect(crc_finish(&crc), 16);
 110 }
 111
 112 //w=16  poly=0x3d65  init=0x0000  refin=true  refout=true  xorout=0xffff  check=0xea82  name="CRC-16/DNP"
 113 uint32_t CRC16_DNP(uint8_t *buff, size_t size) {
 114         crc_t crc;
 115         crc_init_ref(&crc, 16, 0x3d65, 0, 0xffff, TRUE, TRUE);
 116         for ( int i=0; i < size; ++i)
 117                 crc_update(&crc, buff[i], 8);
 118
 119         return BSWAP_16(crc_finish(&crc));
 120 }
 121
 122 //width=16  poly=0x1021  init=0x1d0f  refin=false  refout=false  xorout=0x0000  check=0xe5cc  name="CRC-16/AUG-CCITT"
 123 uint32_t CRC16_CCITT(uint8_t *buff, size_t size) {
 124         crc_t crc;
 125         crc_init(&crc, 16, 0x1021, 0x1d0f, 0);
 126         for ( int i=0; i < size; ++i)
 127                 crc_update(&crc, buff[i], 8);
 128         return  crc_finish(&crc);
 129 }