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 // The CRC as described in ISO 15693-Part 3-Annex C
  16 //      v       buffer with data
  17 //              n       length
  18 //      returns crc as 16bit value
  19 uint16_t Iso15693Crc(uint8_t *v, int n)
  20 {
  21         uint32_t reg;
  22         int i, j;
  23
  24         reg = 0xffff;
  25         for(i = 0; i < n; i++) {
  26                 reg = reg ^ ((uint32_t)v[i]);
  27                 for (j = 0; j < 8; j++) {
  28                         if (reg & 0x0001) {
  29                                 reg = (reg >> 1) ^ 0x8408;
  30                         } else {
  31                                 reg = (reg >> 1);
  32                         }
  33                 }
  34         }
  35
  36         return ~(uint16_t)(reg & 0xffff);
  37 }
  38
  39 // adds a CRC to a dataframe
  40 //      req[]   iso15963 frame without crc
  41 //              n       length without crc
  42 // returns the new length of the dataframe.
  43 int Iso15693AddCrc(uint8_t *req, int n) {
  44         uint16_t crc=Iso15693Crc(req,n);
  45         req[n] = crc & 0xff;
  46         req[n+1] = crc >> 8;
  47         return n+2;
  48 }
  49
  50
  51 int sprintf(char *str, const char *format, ...);
  52
  53 // returns a string representation of the UID
  54 // UID is transmitted and stored LSB first, displayed MSB first
  55 //              target    char* buffer, where to put the UID, if NULL a static buffer is returned
  56 //              uid[]           the UID in transmission order
  57 //      return: ptr to string
  58 char* Iso15693sprintUID(char *target,uint8_t *uid) {
  59   static char tempbuf[2*8+1]="";
  60   if (target==NULL) target=tempbuf;
  61   sprintf(target,"%02hX%02hX%02hX%02hX%02hX%02hX%02hX%02hX",
  62                                 uid[7],uid[6],uid[5],uid[4],uid[3],uid[2],uid[1],uid[0]);
  63   return target;
  64 }
  65
  66
  67