tools/firmware-utils/src/encode_crc.c

   1 /* **************************************************************************
   2
   3    This program creates a CRC checksum and encodes the file that is named
   4    in the command line.
   5
   6    Compile with:  gcc encode_crc.c -Wall -o encode_crc
   7
   8    Author:     Michael Margraf  (michael.margraf@freecom.com)
   9    Copyright:  Freecom Technology GmbH, Berlin, 2004
  10                www.freecom.com
  11
  12   This program is free software; you can redistribute it and/or modify
  13   it under the terms of the GNU General Public License as published by
  14   the Free Software Foundation; either version 2 of the License, or
  15   (at your option) any later version.
  16
  17   This program is distributed in the hope that it will be useful,
  18   but WITHOUT ANY WARRANTY; without even the implied warranty of
  19   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  20   General Public License for more details.
  21
  22   You should have received a copy of the GNU General Public License
  23   along with this program; if not, write to the Free Software
  24   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  25
  26  ************************************************************************* */
  27
  28
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/stat.h>
  33
  34 // *******************************************************************
  35 // CCITT polynom G(x)=x^16+x^12+x^5+1
  36 #define POLYNOM  0x1021
  37
  38 // CRC algorithm with MSB first
  39 int make_crc16(int crc, char new)
  40 {
  41   int i;
  42   crc = crc ^ (((int)new) << 8);
  43
  44   for(i=0; i<8; i++) {  // work on 8 bits in "new"
  45     crc <<= 1;          // MSBs first
  46     if(crc & 0x10000)  crc ^= POLYNOM;
  47   }
  48   return crc & 0xFFFF;
  49 }
  50
  51 // *******************************************************************
  52 // Reads the file "filename" into memory and returns pointer to the buffer.
  53 static char *readfile(char *filename, int *size)
  54 {
  55         FILE            *fp;
  56         char            *buffer;
  57         struct stat     info;
  58
  59         if (stat(filename,&info)!=0)
  60                 return NULL;
  61
  62         if ((fp=fopen(filename,"r"))==NULL)
  63                 return NULL;
  64
  65         buffer=NULL;
  66         for (;;)
  67         {
  68                 if ((buffer=(char *)malloc(info.st_size+1))==NULL)
  69                         break;
  70
  71                 if (fread(buffer,1,info.st_size,fp)!=info.st_size)
  72                 {
  73                         free(buffer);
  74                         buffer=NULL;
  75                         break;
  76                 }
  77
  78                 buffer[info.st_size]='\0';
  79                 if(size) *size = info.st_size;
  80
  81                 break;
  82         }
  83
  84         (void)fclose(fp);
  85
  86         return buffer;
  87 }
  88
  89
  90 // *******************************************************************
  91 int main(int argc, char** argv)
  92 {
  93   if(argc < 3) {
  94     printf("ERROR: Argument missing!\n\n");
  95     return 1;
  96   }
  97
  98   int count;  // size of file in bytes
  99   char *p, *master = readfile(argv[1], &count);
 100   if(!master) {
 101     printf("ERROR: File not found!\n");
 102     return 1;
 103   }
 104
 105   int crc = 0xFFFF, z;
 106
 107   p = master;
 108   for(z=0; z<count; z++)
 109     crc = make_crc16(crc, *(p++));  // calculate CRC
 110   short crc16 = (short)crc;
 111
 112         /*
 113   if(argc > 2) {   // with flag for device recognition ?
 114     p = argv[2];
 115     for(z=strlen(p); z>0; z--) {
 116       crc ^= (int)(*p);
 117       *(p++) = (char)crc;  // encode device flag
 118     }
 119   }
 120         */
 121
 122   p = master;
 123   for(z=0; z<count; z++) {
 124     crc ^= (int)(*p);
 125     *(p++) = (char)crc;  // encode file
 126   }
 127
 128
 129   // write encoded file...
 130   FILE *fp = fopen(argv[2], "w");
 131   if(!fp) {
 132     printf("ERROR: File not writeable!\n");
 133     return 1;
 134   }
 135
 136   if(argc > 3) {  // add flag for device recognition ?
 137     fwrite(argv[3], strlen(argv[3]), sizeof(char), fp);
 138   }
 139   else {
 140     // Device is an FSG, so byte swap (IXP4xx is big endian)
 141     crc16 = ((crc16 >> 8) & 0xFF) | ((crc16 << 8) & 0xFF00);
 142   }
 143
 144   fwrite(&crc16, 1, sizeof(short), fp);     // first write CRC
 145
 146   fwrite(master, count, sizeof(char), fp);  // write content
 147   fclose(fp);
 148
 149   free(master);
 150   return 0;
 151 }