#include <stdio.h>
#include <string.h>
#include "CRC32.h"

#define CRC32_POLY 0x04C11DB7

//using namespace std;

#ifndef _MAX_PATH
#define _MAX_PATH 255
#endif

UINT64 reflect(UINT64 ref, char ch)
{

      UINT64 value(0); 

      // Swap bit 0 for bit 7 
      // bit 1 for bit 6, etc. 
      for(int i = 1; i < (ch + 1); i++) 
      { 
            if(ref & 1) 
                  value |= 1 << (ch - i); 
            ref >>= 1; 
      } 
      return value; 
} 



CRC32::CRC32() {
    UINT32 i, j;
    for (i = 0; i < 256; ++i) {
        crc32_table[i]=(UINT32)(reflect(i, 8) << 24); 
        for (j = 0; j < 8; j++) 
            crc32_table[i] = (crc32_table[i] << 1) ^
                    (crc32_table[i] & (1 << 31) ? CRC32_POLY : 0); 
        crc32_table[i] = (UINT32)reflect(crc32_table[i], 32); 
    }
    reset();
}

UINT32 CRC32::getCrc(const CHAR* filename)
{
    CRC32 crc;

    FILE* file = fopen(filename, "rb");
    int read = fgetc(file);
    while (read != EOF) {
        crc.update((UINT8)read);
        read = fgetc(file);
    }
    fclose(file);

    return crc.getValue();
}

UINT32 CRC32::getCrc(UINT8* image, UINT32 imageSize)
{
    CRC32 crc;
    for (UINT32 i = 0; i < imageSize; i++)
        crc.update(image[i]);

    return crc.getValue();
}

/*
void CRC32::formInternalFilename(CHAR* out, const CHAR* in, const CHAR* ext)
{
    strcpy(out, in);
    char *p = strstr(out, ".zip");
    *p = '\0';
    strcat(out, ext);
    p = &out[strlen((char *)out)];
    while(--p > out)
    {
        if(*p == '\\' || *p == '/')
            break;
    }
    strcpy(out, p+1);
}
*/

void CRC32::reset() {
    crc = 0xFFFFFFFF;
}

void CRC32::update(UINT8 data) {
    crc = (crc >> 8) ^ crc32_table[(crc & 0xFF) ^ data]; 
}

void CRC32::update(UINT8* data, UINT32 length) {
    for (UINT32 i = 0; i < length; i++)
        //crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ data[i]];
        crc = (crc >> 8) ^ crc32_table[(crc & 0xFF) ^ data[i]]; 
}

UINT32 CRC32::getValue() {
    return ~crc;
}