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webp-src/src/dec/idec.c  view on Meta::CPAN

        (uint8_t*)WebPSafeMalloc(extra_size, sizeof(*new_buf));
    if (new_buf == NULL) return 0;
    memcpy(new_buf, old_base, current_size);
    free(mem->buf_);
    mem->buf_ = new_buf;
    mem->buf_size_ = (size_t)extra_size;
    mem->start_ = 0;
    mem->end_ = current_size;
  }

  memcpy(mem->buf_ + mem->end_, data, data_size);
  mem->end_ += data_size;
  assert(mem->end_ <= mem->buf_size_);

  DoRemap(idec, mem->buf_ + mem->start_ - old_base);
  return 1;
}

static int RemapMemBuffer(WebPIDecoder* const idec,
                          const uint8_t* const data, size_t data_size) {
  MemBuffer* const mem = &idec->mem_;
  const uint8_t* const old_base = mem->buf_ + mem->start_;
  assert(mem->mode_ == MEM_MODE_MAP);

  if (data_size < mem->buf_size_) return 0;  // can't remap to a shorter buffer!

  mem->buf_ = (uint8_t*)data;
  mem->end_ = mem->buf_size_ = data_size;

  DoRemap(idec, mem->buf_ + mem->start_ - old_base);
  return 1;
}

static void InitMemBuffer(MemBuffer* const mem) {
  mem->mode_       = MEM_MODE_NONE;
  mem->buf_        = NULL;
  mem->buf_size_   = 0;
  mem->part0_buf_  = NULL;
  mem->part0_size_ = 0;
}

static void ClearMemBuffer(MemBuffer* const mem) {
  assert(mem);
  if (mem->mode_ == MEM_MODE_APPEND) {
    free(mem->buf_);
    free((void*)mem->part0_buf_);
  }
}

static int CheckMemBufferMode(MemBuffer* const mem, MemBufferMode expected) {
  if (mem->mode_ == MEM_MODE_NONE) {
    mem->mode_ = expected;    // switch to the expected mode
  } else if (mem->mode_ != expected) {
    return 0;         // we mixed the modes => error
  }
  assert(mem->mode_ == expected);   // mode is ok
  return 1;
}

//------------------------------------------------------------------------------
// Macroblock-decoding contexts

static void SaveContext(const VP8Decoder* dec, const VP8BitReader* token_br,
                        MBContext* const context) {
  const VP8BitReader* const br = &dec->br_;
  const VP8MB* const left = dec->mb_info_ - 1;
  const VP8MB* const info = dec->mb_info_ + dec->mb_x_;

  context->left_ = *left;
  context->info_ = *info;
  context->br_ = *br;
  context->token_br_ = *token_br;
  memcpy(context->intra_t_, dec->intra_t_ + 4 * dec->mb_x_, 4);
  memcpy(context->intra_l_, dec->intra_l_, 4);
}

static void RestoreContext(const MBContext* context, VP8Decoder* const dec,
                           VP8BitReader* const token_br) {
  VP8BitReader* const br = &dec->br_;
  VP8MB* const left = dec->mb_info_ - 1;
  VP8MB* const info = dec->mb_info_ + dec->mb_x_;

  *left = context->left_;
  *info = context->info_;
  *br = context->br_;
  *token_br = context->token_br_;
  memcpy(dec->intra_t_ + 4 * dec->mb_x_, context->intra_t_, 4);
  memcpy(dec->intra_l_, context->intra_l_, 4);
}

//------------------------------------------------------------------------------

static VP8StatusCode IDecError(WebPIDecoder* const idec, VP8StatusCode error) {
  if (idec->state_ == STATE_VP8_DATA) {
    VP8Io* const io = &idec->io_;
    if (io->teardown) {
      io->teardown(io);
    }
  }
  idec->state_ = STATE_ERROR;
  return error;
}

static void ChangeState(WebPIDecoder* const idec, DecState new_state,
                        size_t consumed_bytes) {
  MemBuffer* const mem = &idec->mem_;
  idec->state_ = new_state;
  mem->start_ += consumed_bytes;
  assert(mem->start_ <= mem->end_);
  idec->io_.data = mem->buf_ + mem->start_;
  idec->io_.data_size = MemDataSize(mem);
}

// Headers
static VP8StatusCode DecodeWebPHeaders(WebPIDecoder* const idec) {
  MemBuffer* const mem = &idec->mem_;
  const uint8_t* data = mem->buf_ + mem->start_;
  size_t curr_size = MemDataSize(mem);
  VP8StatusCode status;
  WebPHeaderStructure headers;