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