Decompress

rle.c

u32 rle_decompress(u8** out, const u8* src) {
  // Extract the size of the data
  u32 originalSize = *((u32*) src) >> 8;
  u8* originalDst = calloc(originalSize, 1);

  // Advance past the header
  src += sizeof(u32);

  u8* dst = originalDst;
  for(u32 size = originalSize; size > 0;) {
    u8 byte = *src++;

    // Check if it's a compressed block
    if (byte & 0x80) {
      // Read the length of the block
      int len = (byte & 0x7F) + 3;
      size -= len;

      // Read in the byte used for the run
      byte = *src++;

      memset(dst, byte, len);
      dst += len;
    } else /* Uncompressed block */ {
      // Read the length of uncompressed bytes
      int len = (byte & 0x7F) + 1;
      size -= len;

      memcpy(dst, src, len);
      dst += len;
      src += len;
    }
  }

  *out = originalDst;
  return originalSize;
}