69 lines
1.4 KiB
C
Executable File
69 lines
1.4 KiB
C
Executable File
#include <stdio.h>
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#include <stdlib.h>
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#include <sys/file.h>
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#include <sys/types.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <limits.h>
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#include <endian.h>
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int
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main(int argc, char *argv[])
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{
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if (argc != 4) {
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return 1;
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}
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int fdin = open(argv[1], O_RDONLY);
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int fdout = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0666);
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if (fdin == -1 || fdout == -1) {
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return 1;
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}
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char *p;
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errno = 0;
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long long mod = strtoll(argv[3], &p, 10);
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if (errno || *p || p == argv[3] || !mod || (int32_t) mod != mod) {
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return 1;
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}
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unsigned long long res = 0;
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unsigned long long num = 1;
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unsigned char buf;
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int r = read(fdin, &buf, sizeof(buf));
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if (r && r != sizeof(buf)) {
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return 1;
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}
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while (r > 0) {
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for (int i = 0; i < CHAR_BIT; i++) {
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num %= mod;
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res += (num * num) % mod;
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res %= mod;
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if (buf & (1 << i)) {
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int32_t res32 = res;
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if (write(fdout, &res32, sizeof(res32)) == -1) {
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return 1;
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}
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}
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num++;
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}
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r = read(fdin, &buf, sizeof(buf));
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if (r && r != sizeof(buf)) {
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return 1;
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}
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}
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if (r == -1) {
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return 1;
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}
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close(fdin);
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close(fdout);
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return 0;
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}
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