tools/firmware-utils/src/encode_crc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* **************************************************************************
   3
   4    This program creates a CRC checksum and encodes the file that is named
   5    in the command line.
   6
   7    Compile with:  gcc encode_crc.c -Wall -o encode_crc
   8
   9    Author:     Michael Margraf  (michael.margraf@freecom.com)
  10    Copyright:  Freecom Technology GmbH, Berlin, 2004
  11                www.freecom.com
  12
  13  ************************************************************************* */
  14
  15
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <sys/stat.h>
  20
  21 // *******************************************************************
  22 // CCITT polynom G(x)=x^16+x^12+x^5+1
  23 #define POLYNOM  0x1021
  24
  25 // CRC algorithm with MSB first
  26 int make_crc16(int crc, char new)
  27 {
  28   int i;
  29   crc = crc ^ (((int)new) << 8);
  30
  31   for(i=0; i<8; i++) {  // work on 8 bits in "new"
  32     crc <<= 1;          // MSBs first
  33     if(crc & 0x10000)  crc ^= POLYNOM;
  34   }
  35   return crc & 0xFFFF;
  36 }
  37
  38 // *******************************************************************
  39 // Reads the file "filename" into memory and returns pointer to the buffer.
  40 static char *readfile(char *filename, int *size)
  41 {
  42         FILE            *fp;
  43         char            *buffer;
  44         struct stat     info;
  45
  46         if (stat(filename,&info)!=0)
  47                 return NULL;
  48
  49         if ((fp=fopen(filename,"r"))==NULL)
  50                 return NULL;
  51
  52         buffer=NULL;
  53         for (;;)
  54         {
  55                 if ((buffer=(char *)malloc(info.st_size+1))==NULL)
  56                         break;
  57
  58                 if (fread(buffer,1,info.st_size,fp)!=info.st_size)
  59                 {
  60                         free(buffer);
  61                         buffer=NULL;
  62                         break;
  63                 }
  64
  65                 buffer[info.st_size]='\0';
  66                 if(size) *size = info.st_size;
  67
  68                 break;
  69         }
  70
  71         (void)fclose(fp);
  72
  73         return buffer;
  74 }
  75
  76
  77 // *******************************************************************
  78 int main(int argc, char** argv)
  79 {
  80   if(argc < 3) {
  81     printf("ERROR: Argument missing!\n\n");
  82     return 1;
  83   }
  84
  85   int count;  // size of file in bytes
  86   char *p, *master = readfile(argv[1], &count);
  87   if(!master) {
  88     printf("ERROR: File not found!\n");
  89     return 1;
  90   }
  91
  92   int crc = 0xFFFF, z;
  93
  94   p = master;
  95   for(z=0; z<count; z++)
  96     crc = make_crc16(crc, *(p++));  // calculate CRC
  97   short crc16 = (short)crc;
  98
  99         /*
 100   if(argc > 2) {   // with flag for device recognition ?
 101     p = argv[2];
 102     for(z=strlen(p); z>0; z--) {
 103       crc ^= (int)(*p);
 104       *(p++) = (char)crc;  // encode device flag
 105     }
 106   }
 107         */
 108
 109   p = master;
 110   for(z=0; z<count; z++) {
 111     crc ^= (int)(*p);
 112     *(p++) = (char)crc;  // encode file
 113   }
 114
 115
 116   // write encoded file...
 117   FILE *fp = fopen(argv[2], "w");
 118   if(!fp) {
 119     printf("ERROR: File not writeable!\n");
 120     return 1;
 121   }
 122
 123   if(argc > 3) {  // add flag for device recognition ?
 124     fwrite(argv[3], strlen(argv[3]), sizeof(char), fp);
 125   }
 126   else {
 127     // Device is an FSG, so byte swap (IXP4xx is big endian)
 128     crc16 = ((crc16 >> 8) & 0xFF) | ((crc16 << 8) & 0xFF00);
 129   }
 130
 131   fwrite(&crc16, 1, sizeof(short), fp);     // first write CRC
 132
 133   fwrite(master, count, sizeof(char), fp);  // write content
 134   fclose(fp);
 135
 136   free(master);
 137   return 0;
 138 }