DLLEXPORT double adler32_file(char* filename)
{
    FILE * ptrFile = fopen(filename, "rb");

    if (ptrFile == NULL) return(-1);

    fseek(ptrFile, 0, SEEK_END);
    long lSize = ftell(ptrFile);
    rewind(ptrFile);

    char * buffer = (char*)malloc(sizeof(char) * lSize);
    if (buffer == NULL) return(-2);

    size_t result = fread(buffer, 1, lSize, ptrFile);
    if (result != lSize) return(-3);

    puts(buffer);

    int buffSize = strlen(buffer);
    unsigned long s1 = 1;
    unsigned long s2 = 0;

    for (int i = 0; i <= buffSize; i++) {
        s1 = (s1 + buffer[i]) % 65521;
        s2 = (s2 + s1) % 65521;
    }

    fclose(ptrFile);
    free(buffer);
    return (s2 << 16) + s1;
}

FILE * ptrFile = fopen(filename, "rb");

    if (ptrFile == NULL) return(-1);

    long pSize = (1024 * 1024 * 1024) * 16;

    unsigned char * buffer = (unsigned char*)malloc(sizeof(unsigned char) * pSize);
    if (buffer == NULL) return(-2);

    unsigned long s1 = 1;
    unsigned long s2 = 0;

    while (true) {
        size_t result = fread(buffer, 1, pSize, ptrFile);

        for (int i = 0; i < result; i++) {
            s1 = (s1 + buffer[i]) % 65521;
            s2 = (s2 + s1) % 65521;
        }

  if (feof(ptrFile)) break;
    }

    fclose(ptrFile);
    free(buffer);
    return (s2 << 16) + s1;

DLLEXPORT double adler32_file(char* filename)
{
    FILE * ptrFile = fopen(filename, "rb");

    if (ptrFile == NULL) return(-1);

    const unsigned int pSize = 1024 * 128;

    unsigned char * buffer = (unsigned char*)malloc(pSize);
    if (buffer == NULL) return(-2);
    
    unsigned long s1 = 1, s2 = 0;

    size_t result;
    while (true) {
        result = fread(buffer, 1, pSize, ptrFile);

        for (int i = 0; i < result; i++){
            s1 = s1 + buffer[i];
            if (s1 > 65520) s1 %= 65521;
            s2 = s2 + s1;
            if (s2 > 65520) s2 %= 65521;
        }
        if (result != pSize) break;
    }

    fclose(ptrFile);
    free(buffer);
    return (s2 << 16) + s1;
}