Function mad_header_decode

modules/data/mp3/libmad/frame.c:296–428

* NAME: header->decode() * DESCRIPTION: read the next frame header from the stream */

 * DESCRIPTION:	read the next frame header from the stream
 */
int mad_header_decode(struct mad_header *header, struct mad_stream *stream)
{
  register unsigned char const *ptr, *end;
  unsigned int pad_slot, N;

  ptr = stream->next_frame;
  end = stream->bufend;

  if (ptr == 0) {
    stream->error = MAD_ERROR_BUFPTR;
    goto fail;
  }

  /* stream skip */
  if (stream->skiplen) {
    if (!stream->sync)
      ptr = stream->this_frame;

    if ((unsigned int)(end - ptr) < stream->skiplen) {
      stream->skiplen   -= end - ptr;
      stream->next_frame = end;

      stream->error = MAD_ERROR_BUFLEN;
      goto fail;
    }

    ptr += stream->skiplen;
    stream->skiplen = 0;

    stream->sync = 1;
  }

 sync:
  /* synchronize */
  if (stream->sync) {
    if (end - ptr < MAD_BUFFER_GUARD) {
      stream->next_frame = ptr;

      stream->error = MAD_ERROR_BUFLEN;
      goto fail;
    }
    else if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) {
      /* mark point where frame sync word was expected */
      stream->this_frame = ptr;
      stream->next_frame = ptr + 1;

      stream->error = MAD_ERROR_LOSTSYNC;
      goto fail;
    }
  }
  else {
    mad_bit_init(&stream->ptr, ptr);

    if (mad_stream_sync(stream) == -1) {
      if (end - stream->next_frame >= MAD_BUFFER_GUARD)
	stream->next_frame = end - MAD_BUFFER_GUARD;

      stream->error = MAD_ERROR_BUFLEN;