48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
/*
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* Sum bytes in file mod 2^16
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*/
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#include <stdio.h>
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#include <stdlib.h>
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int main(int argc, char **argv)
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{
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unsigned sum;
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int i, c;
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FILE *f;
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long nbytes;
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int errflg = 0;
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i = 1;
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do {
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if (i < argc) {
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if ((f = fopen(argv[i], "r")) == NULL) {
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fprintf(stderr, "sum: Can't open %s\n", argv[i]);
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errflg += 10;
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continue;
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}
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} else
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f = stdin;
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sum = 0;
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nbytes = 0;
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while ((c = getc(f)) != EOF) {
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nbytes++;
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if (sum & 01)
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sum = (sum >> 1) + 0x8000;
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else
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sum >>= 1;
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sum += c;
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sum &= 0xFFFF;
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}
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if (ferror(f)) {
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errflg++;
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fprintf(stderr, "sum: read error on %s\n", argc > 1 ? argv[i] : "-");
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}
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printf("%05u%6ld", sum, (nbytes + BUFSIZ - 1) / BUFSIZ);
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if (argc > 2)
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printf(" %s", argv[i]);
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printf("\n");
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fclose(f);
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} while (++i < argc);
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exit(errflg);
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}
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