mycrc32.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>
#include <immintrin.h>
#include <omp.h>

#define READ_BINARY "rb"

#define CHUNK_SIZE (1024 * 1024 * 10)

unsigned int crc32c (unsigned char *buf, int len, unsigned int crc)
{
        unsigned int i;
        uint64_t * bp64 = (uint64_t *) buf;

        for (i = 0; i < (len - (len % 8)) / 8; i++)
        {
                crc = _mm_crc32_u64 ((uint64_t) crc, bp64[i]);
        }
        for (i *= 8; i < len; i++)
        {
                crc = _mm_crc32_u8 (crc, buf[i]);
        }

        return crc;
}

int main(int argc, char *argv[]) {
        struct stat st;
        char *buf = malloc(CHUNK_SIZE);

        char *filename = argv[1];
        stat(filename, &st);

        off_t fsize = st.st_size;

        FILE *fp = fopen64(filename, READ_BINARY);
        if (fp == NULL) {
                printf("%s is not exist\n", filename);
        }

        size_t readed = 0;
        size_t wread = 0;
        unsigned int crc = 0;
        while (fsize > 0) {
            wread = fsize > CHUNK_SIZE ? CHUNK_SIZE : fsize;
            readed = fread(buf, wread, 1, fp);
            crc = crc32c((unsigned char*)buf, wread, 0);
            fsize -= wread;
            printf("%ld\n", crc);
        }
  
        fclose(fp);
        free(buf);
        return 0;
}