git.zerfleddert.de Git - proxmark3-svn/blob - common/iso15693tools.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 // ISO15693 CRC & other commons
   7 //-----------------------------------------------------------------------------
   8
   9
  10 #include "proxmark3.h"
  11 #include <stdint.h>
  12 #include <stdlib.h>
  13 //#include "iso15693tools.h"
  14 #ifdef ON_DEVICE
  15 #include "printf.h"
  16 #else
  17 #include <stdio.h>
  18 #endif
  19
  20
  21 #define POLY 0x8408
  22
  23
  24 // The CRC as described in ISO 15693-Part 3-Annex C
  25 //      v       buffer with data
  26 //              n       length
  27 //      returns crc as 16bit value
  28 uint16_t Iso15693Crc(uint8_t *v, int n)
  29 {
  30         uint32_t reg;
  31         int i, j;
  32
  33         reg = 0xffff;
  34         for(i = 0; i < n; i++) {
  35                 reg = reg ^ ((uint32_t)v[i]);
  36                 for (j = 0; j < 8; j++) {
  37                         if (reg & 0x0001) {
  38                                 reg = (reg >> 1) ^ 0x8408;
  39                         } else {
  40                                 reg = (reg >> 1);
  41                         }
  42                 }
  43         }
  44
  45         return ~(uint16_t)(reg & 0xffff);
  46 }
  47
  48 // adds a CRC to a dataframe
  49 //      req[]   iso15963 frame without crc
  50 //              n       length without crc
  51 // returns the new length of the dataframe.
  52 int Iso15693AddCrc(uint8_t *req, int n) {
  53         uint16_t crc=Iso15693Crc(req,n);
  54         req[n] = crc & 0xff;
  55         req[n+1] = crc >> 8;
  56         return n+2;
  57 }
  58
  59
  60 // returns a string representation of the UID
  61 // UID is transmitted and stored LSB first, displayed MSB first
  62 //              target    char* buffer, where to put the UID, if NULL a static buffer is returned
  63 //              uid[]           the UID in transmission order
  64 //      return: ptr to string
  65 char* Iso15693sprintUID(char *target,uint8_t *uid) {
  66   static char tempbuf[2*8+1]="";
  67   if (target==NULL) target=tempbuf;
  68   sprintf(target,"%02X%02X%02X%02X%02X%02X%02X%02X",
  69                                 uid[7],uid[6],uid[5],uid[4],uid[3],uid[2],uid[1],uid[0]);
  70   return target;
  71 }
  72
  73 uint16_t iclass_crc16(char *data_p, unsigned short length)
  74 {
  75       unsigned char i;
  76       unsigned int data;
  77           uint16_t crc = 0xffff;
  78
  79       if (length == 0)
  80             return (~crc);
  81
  82       do
  83       {
  84             for (i=0, data=(unsigned int)0xff & *data_p++;
  85                  i < 8;
  86                  i++, data >>= 1)
  87             {
  88                   if ((crc & 0x0001) ^ (data & 0x0001))
  89                         crc = (crc >> 1) ^ POLY;
  90                   else  crc >>= 1;
  91             }
  92       } while (--length);
  93
  94       crc = ~crc;
  95       data = crc;
  96       crc = (crc << 8) | (data >> 8 & 0xff);
  97       crc = crc ^ 0xBC3;
  98       return (crc);
  99 }
 100