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#include <stdio.h>

unsigned char src[5000000];

unsigned char dest[10000000];

unsigned char dec[10000000];

#define CRC(x) (crc = (crc << 5) | (x))

unsigned long compress (unsigned char *in, unsigned char *out, unsigned long size)

{

  unsigned char hist[0x10000] = {0};

  unsigned char *mask;

  unsigned short hash = 0;

  unsigned i, b;

  unsigned long csize = 5;

  unsigned long crc = 0;

  *out++ = (size >> 24) & 0xff;

  *out++ = (size >> 16) & 0xff;

  *out++ = (size >> 8) & 0xff;

  *out++ = (size >> 0) & 0xff;

  mask = out++;

  *mask = 0;

  for (i = 0, b = 0; i < size; i++) {

    CRC(*in);

    if (*in == hist[hash]) *mask |= 1 << b;

    else {

      *out++ = *in;

      csize++;

    }

    hist[hash] = *in;

    hash <<= 8;

    hash |= *in;

    if (++b == 8) {

      mask = out++;

      csize++;

      *mask = 0;

      b = 0;

    }

    in++;

  }

  printf ("original CRC = %08x\n", crc);

  return csize;

}

unsigned long decompress (unsigned char *in, unsigned char *out)

{

  unsigned char hist[0x10000] = {0};

  unsigned long size;

  int b = 0, i;

  unsigned char *mask;

  unsigned short hash = 0;

  unsigned long crc = 0;

  CRC(*in); size = (*in++) << 24;

  CRC(*in); size |= (*in++) << 16;

  CRC(*in); size |= (*in++) << 8;

  CRC(*in); size |= (*in++) << 0;

  CRC(*in); mask = in++;

  for (i = 0; i < size; i++) {

    unsigned char c;

    if ((*mask >> b) & 1) c = hist[hash];

    else CRC(c = *in++);

    *out++ = c;

    hist[hash] = c;

    hash <<= 8;

    hash |= c;

    hash &= 0xffff;

    if (++b == 8) {

      CRC(*in);

      mask = in++;

      b = 0;

    }

  }

  printf ("compressed CRC = %08x\n", crc);

  return size;

}

int main (int argc, char *argv[])

{

  FILE *fi;

  unsigned short hash = 0;

  int i, size;

  char tmp[50];

  unsigned long crc = 0;

  if (argc != 2) return -1;

  fi = fopen (argv[1], "rb");

  if (!fi) return 1;

  size = fread (src, 1, sizeof (src), fi);

  fclose (fi);

  printf ("original size = %i (%08x)\n", size, size);

  size = compress (src, dest, size);

  printf ("compressed size = %i (%08x)\n", size, size);

  sprintf (tmp, "%s.cmp", argv[1]);

  fi = fopen (tmp, "wb+");

  fwrite (dest, 1, size, fi);

  fclose (fi);

  size = decompress (dest, dec);

  printf ("decompressed size = %i (%08x)\n", size, size);

  for (i = 0; i < size; i++)

    if (src[i] != dec[i]) {

      printf ("error!\n");

      return 1;

    }

#if 0

  fi = fopen ("fl_img.dec", "wb+");

  fwrite (dec, 1, size, fi);

  fclose (fi);

#endif

  return 0;

}