90 lines
1.5 KiB
C
90 lines
1.5 KiB
C
/* berechnet EPROM Checksummen */
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#include <stdio.h>
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static void usage(char *);
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int main(int argc, char **argv) {
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char d,e,a1,a2;
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int i,begin=0,end=-1,c;
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FILE *f;
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char *filename;
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if(argc < 2 || argc > 4 )
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usage(argv[0]);
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filename = argv[1];
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if(argc > 2)
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begin = atoi(argv[2]);
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if(argc > 3)
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end = atoi(argv[3]);
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if( end != -1 && begin > end ) {
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fprintf(stderr, "begin adress cannot be higher than end adress\n");
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usage(argv[0]);
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}
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if( ! ( f = fopen(filename, "rb") ) ) {
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fprintf(stderr, "cannot open %s \n", filename);
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usage(argv[0]);
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}
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fseek(f,begin,SEEK_SET);
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d=0xff; e=0xff;
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c=begin;
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while(!feof(f)) {
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if( end != -1 && c == end )
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break;
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else
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c++;
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a1 = fgetc(f);
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if( ferror(f) ) {
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printf("File error\n");
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break;
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}
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if( feof(f) ) {
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break;
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}
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a1=a1 ^ d;
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d=a1;
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for (i=0;i<4;i++)
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{if ((a1 & 1)> 0) {a1=a1 >> 1; a1=a1 | 0x80;}
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else {a1=a1 >> 1; a1=a1 & 0x7f;}}
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a1=a1 & 0x0f;
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a1=a1 ^ d;
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d=a1;
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for (i=0;i<3;i++)
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{if ((a1 & 1)>0) {a1=a1 >> 1; a1=a1 | 0x80;}
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else {a1=a1 >> 1; a1=a1 & 0x7f;}}
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a2=a1;
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a1=a1 & 0x1f;
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a1=a1 ^ e;
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e=a1;
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a1=a2;
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if ((a1 & 1)>0) {a1=a1 >> 1; a1=a1 | 0x80;}
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else {a1=a1 >> 1; a1=a1 & 0x7f;}
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a1=a1 & 0xf0;
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a1=a1 ^ e;
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e=a1;
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a1=a2;
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a1=a1 & 0xe0;
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a1=a1 ^ d;
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d=e;
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e=a1;
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}
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fclose(f);
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printf ("%s %02x%02x\n","crc_checksum:",d & 0xff,e & 0xff);
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return 0;
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}
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static void usage(char *progname) {
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printf("usage: %s file [start adress] [end adress]\n", progname);
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exit(1);
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}
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