#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

static uint64_t fnv1a64_bytes(const void *data, size_t n, uint64_t h) [[unsequenced]] {
    const uint8_t *p = (const uint8_t *)data;
    for (size_t i = 0; i < n; ++i) {
        h ^= p[i];
        h *= 1099511628211ull;
    }
    return h;
}

static uint64_t fnv1a64_file(const char filepath[static 1]) {
    FILE *f = fopen(filepath, "rb");
    if (!f)
        return 0;
    uint64_t h = 1469598103934665603ull;
    static constexpr size_t BUF_SIZE = 16384;
    char buf[BUF_SIZE];
    size_t bytes = 0;

    while ((bytes = fread(buf, sizeof(char), BUF_SIZE, f)) != 0) {
        h = fnv1a64_bytes(buf, bytes, h);
    }
    fclose(f);
    return h;
}

int main(int argc, char **argv) {
    if (argc != 2) {
        printf("Incorrect arguments.\n");
        return EXIT_FAILURE;
    }
    uint64_t hash_value = fnv1a64_file(argv[1]);
    printf("%s: 0x%lx\n", argv[1], hash_value);
    return EXIT_SUCCESS;
}