#include <stdbool.h>
#include "checksum.h"

static void init_crc32_tab(void);
static bool crc_tab32_init = false;
static uint32_t	crc_tab32[256];

static void init_crc32_tab(void) {

    uint32_t i;
    uint32_t j;
    uint32_t crc;

    for (i = 0; i < 256; i++) {
        crc = i;
        for (j = 0; j < 8; j++) {
            if (crc & 0x00000001L) {
                crc = (crc >> 1) ^ CRC_POLY_32;
            }
            else {
                crc = crc >> 1;
            }
        }
        crc_tab32[i] = crc;
    }
    crc_tab32_init = true;
}

const char* checkbrute_format()
{
    return "JAMCRC";
}

const char* checkbrute_version()
{
    return "0.1";
}

uint32_t checkbrute_hash32(unsigned char* data, size_t size)
{
    uint32_t crc;
    uint32_t tmp;
    uint32_t long_c;
    const unsigned char *ptr;
    size_t a;

    if (!crc_tab32_init)
        init_crc32_tab();

    crc = CRC_START_32;
    ptr = data;

    if (ptr != NULL)
        for (a = 0; a < size; a++) {
            long_c = 0x000000FFL & (uint32_t)*ptr;
            tmp = crc ^ long_c;
            crc = (crc >> 8) ^ crc_tab32[tmp & 0xff];
            ptr++;
        }

    crc ^= 0x00000000L;

    return crc & 0xffffffffL;
}

int checkbrute_hashsz()
{
    return 4;
}