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src/Source/LibWebP/src/dec/dec.idec.c  view on Meta::CPAN

      MBContext context;
      SaveContext(dec, token_br, &context);
      if (!VP8DecodeMB(dec, token_br)) {
        // We shouldn't fail when MAX_MB data was available
        if (dec->num_parts_ == 1 && MemDataSize(&idec->mem_) > MAX_MB_SIZE) {
          return IDecError(idec, VP8_STATUS_BITSTREAM_ERROR);
        }
        RestoreContext(&context, dec, token_br);
        return VP8_STATUS_SUSPENDED;
      }
      // Release buffer only if there is only one partition
      if (dec->num_parts_ == 1) {
        idec->mem_.start_ = token_br->buf_ - idec->mem_.buf_;
        assert(idec->mem_.start_ <= idec->mem_.end_);
      }
    }
    VP8InitScanline(dec);   // Prepare for next scanline

    // Reconstruct, filter and emit the row.
    if (!VP8ProcessRow(dec, io)) {
      return IDecError(idec, VP8_STATUS_USER_ABORT);
    }
  }
  // Synchronize the thread and check for errors.
  if (!VP8ExitCritical(dec, io)) {
    return IDecError(idec, VP8_STATUS_USER_ABORT);
  }
  dec->ready_ = 0;
  return FinishDecoding(idec);
}

static VP8StatusCode ErrorStatusLossless(WebPIDecoder* const idec,
                                         VP8StatusCode status) {
  if (status == VP8_STATUS_SUSPENDED || status == VP8_STATUS_NOT_ENOUGH_DATA) {
    return VP8_STATUS_SUSPENDED;
  }
  return IDecError(idec, status);
}

static VP8StatusCode DecodeVP8LHeader(WebPIDecoder* const idec) {
  VP8Io* const io = &idec->io_;
  VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
  const WebPDecParams* const params = &idec->params_;
  WebPDecBuffer* const output = params->output;
  size_t curr_size = MemDataSize(&idec->mem_);
  assert(idec->is_lossless_);

  // Wait until there's enough data for decoding header.
  if (curr_size < (idec->chunk_size_ >> 3)) {
    dec->status_ = VP8_STATUS_SUSPENDED;
    return ErrorStatusLossless(idec, dec->status_);
  }

  if (!VP8LDecodeHeader(dec, io)) {
    if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR &&
        curr_size < idec->chunk_size_) {
      dec->status_ = VP8_STATUS_SUSPENDED;
    }
    return ErrorStatusLossless(idec, dec->status_);
  }
  // Allocate/verify output buffer now.
  dec->status_ = WebPAllocateDecBuffer(io->width, io->height, params->options,
                                       output);
  if (dec->status_ != VP8_STATUS_OK) {
    return IDecError(idec, dec->status_);
  }

  idec->state_ = STATE_VP8L_DATA;
  return VP8_STATUS_OK;
}

static VP8StatusCode DecodeVP8LData(WebPIDecoder* const idec) {
  VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
  const size_t curr_size = MemDataSize(&idec->mem_);
  assert(idec->is_lossless_);

  // Switch to incremental decoding if we don't have all the bytes available.
  dec->incremental_ = (curr_size < idec->chunk_size_);

  if (!VP8LDecodeImage(dec)) {
    return ErrorStatusLossless(idec, dec->status_);
  }
  assert(dec->status_ == VP8_STATUS_OK || dec->status_ == VP8_STATUS_SUSPENDED);
  return (dec->status_ == VP8_STATUS_SUSPENDED) ? dec->status_
                                                : FinishDecoding(idec);
}

  // Main decoding loop
static VP8StatusCode IDecode(WebPIDecoder* idec) {
  VP8StatusCode status = VP8_STATUS_SUSPENDED;

  if (idec->state_ == STATE_WEBP_HEADER) {
    status = DecodeWebPHeaders(idec);
  } else {
    if (idec->dec_ == NULL) {
      return VP8_STATUS_SUSPENDED;    // can't continue if we have no decoder.
    }
  }
  if (idec->state_ == STATE_VP8_HEADER) {
    status = DecodeVP8FrameHeader(idec);
  }
  if (idec->state_ == STATE_VP8_PARTS0) {
    status = DecodePartition0(idec);
  }
  if (idec->state_ == STATE_VP8_DATA) {
    status = DecodeRemaining(idec);
  }
  if (idec->state_ == STATE_VP8L_HEADER) {
    status = DecodeVP8LHeader(idec);
  }
  if (idec->state_ == STATE_VP8L_DATA) {
    status = DecodeVP8LData(idec);
  }
  return status;
}

//------------------------------------------------------------------------------
// Public functions

WebPIDecoder* WebPINewDecoder(WebPDecBuffer* output_buffer) {
  WebPIDecoder* idec = (WebPIDecoder*)WebPSafeCalloc(1ULL, sizeof(*idec));