Function WriteCompressionByte

Descent3/LoadLevel.cpp:2226–2281

Does a RLE compression run of the values given the byte array 'val'.

// Does a RLE compression run of the values given the byte array 'val'.
int WriteCompressionByte(CFILE *fp, uint8_t *val, int total, int just_count, int compress) {
  int done = 0;
  int written = 0;
  int curptr = 0;

  ASSERT(!(just_count == 1 && compress == 0));

  if (compress == NO_COMPRESS) {
    int i;

    // Write 0 to indicate no compression
    cf_WriteByte(fp, NO_COMPRESS);
    for (i = 0; i < total; i++)
      cf_WriteByte(fp, val[i]);

    return total;
  } else {
    // Indicate compression
    if (!just_count)
      cf_WriteByte(fp, COMPRESS);
  }

  while (!done) {
    if (curptr == total) {
      done = 1;
      continue;
    }

    ASSERT(curptr < total);

    uint8_t curval = val[curptr];
    uint8_t count = 1;

    while ((curptr + count) < total && val[curptr + count] == curval && count < 250)
      count++;

    written += 2;

    if (just_count) {
      curptr += count;
      continue;
    }

    if (count == 1) {
      cf_WriteByte(fp, 0);
      cf_WriteByte(fp, curval);
    } else {
      cf_WriteByte(fp, count);
      cf_WriteByte(fp, curval);
    }

    curptr += count;
  }

  return written;
}

// Does a RLE compression run of the values given the int16_t array 'val'.