/* ************************************************************************** This program creates a CRC checksum and encodes the file that is named in the command line. Compile with: gcc encode_crc.c -Wall -o encode_crc Author: Michael Margraf (michael.margraf@freecom.com) Copyright: Freecom Technology GmbH, Berlin, 2004 www.freecom.com This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA ************************************************************************* */ #include #include #include #include // ******************************************************************* // CCITT polynom G(x)=x^16+x^12+x^5+1 #define POLYNOM 0x1021 // CRC algorithm with MSB first int make_crc16(int crc, char new) { int i; crc = crc ^ (((int)new) << 8); for(i=0; i<8; i++) { // work on 8 bits in "new" crc <<= 1; // MSBs first if(crc & 0x10000) crc ^= POLYNOM; } return crc & 0xFFFF; } // ******************************************************************* // Reads the file "filename" into memory and returns pointer to the buffer. static char *readfile(char *filename, int *size) { FILE *fp; char *buffer; struct stat info; if (stat(filename,&info)!=0) return NULL; if ((fp=fopen(filename,"r"))==NULL) return NULL; buffer=NULL; for (;;) { if ((buffer=(char *)malloc(info.st_size+1))==NULL) break; if (fread(buffer,1,info.st_size,fp)!=info.st_size) { free(buffer); buffer=NULL; break; } buffer[info.st_size]='\0'; if(size) *size = info.st_size; break; } (void)fclose(fp); return buffer; } // ******************************************************************* int main(int argc, char** argv) { if(argc < 3) { printf("ERROR: Argument missing!\n\n"); return 1; } int count; // size of file in bytes char *p, *master = readfile(argv[1], &count); if(!master) { printf("ERROR: File not found!\n"); return 1; } int crc = 0xFFFF, z; p = master; for(z=0; z 2) { // with flag for device recognition ? p = argv[2]; for(z=strlen(p); z>0; z--) { crc ^= (int)(*p); *(p++) = (char)crc; // encode device flag } } */ p = master; for(z=0; z 3) { // add flag for device recognition ? fwrite(argv[3], strlen(argv[3]), sizeof(char), fp); } else { // Device is an FSG, so byte swap (IXP4xx is big endian) crc16 = ((crc16 >> 8) & 0xFF) | ((crc16 << 8) & 0xFF00); } fwrite(&crc16, 1, sizeof(short), fp); // first write CRC fwrite(master, count, sizeof(char), fp); // write content fclose(fp); free(master); return 0; } 5 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202