3rdparty/libwebp/dec/idec.c

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This source file includes following definitions.
RemapBitReader
MemDataSize
NeedCompressedAlpha
DoRemap
AppendToMemBuffer
RemapMemBuffer
InitMemBuffer
ClearMemBuffer
CheckMemBufferMode
SaveContext
RestoreContext
IDecError
ChangeState
DecodeWebPHeaders
DecodeVP8FrameHeader
CopyParts0Data
DecodePartition0
DecodeRemaining
ErrorStatusLossless
DecodeVP8LHeader
DecodeVP8LData
IDecode
WebPINewDecoder
WebPIDelete
WebPINewRGB
WebPINewYUVA
WebPINewYUV
IDecCheckStatus
WebPIAppend
WebPIUpdate
GetOutputBuffer
WebPIDecodedArea
WebPIDecGetRGB
WebPIDecGetYUVA
WebPISetIOHooks
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Incremental decoding
//
// Author: somnath@google.com (Somnath Banerjee)

#include <assert.h>
#include <string.h>
#include <stdlib.h>

#include "./webpi.h"
#include "./vp8i.h"
#include "../utils/utils.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

// In append mode, buffer allocations increase as multiples of this value.
// Needs to be a power of 2.
#define CHUNK_SIZE 4096
#define MAX_MB_SIZE 4096

//------------------------------------------------------------------------------
// Data structures for memory and states

// Decoding states. State normally flows like HEADER->PARTS0->DATA->DONE.
// If there is any error the decoder goes into state ERROR.
typedef enum {
  STATE_PRE_VP8,  // All data before that of the first VP8 chunk.
  STATE_VP8_FRAME_HEADER,  // For VP8 Frame header (within VP8 chunk).
  STATE_VP8_PARTS0,
  STATE_VP8_DATA,
  STATE_VP8L_HEADER,
  STATE_VP8L_DATA,
  STATE_DONE,
  STATE_ERROR
} DecState;

// Operating state for the MemBuffer
typedef enum {
  MEM_MODE_NONE = 0,
  MEM_MODE_APPEND,
  MEM_MODE_MAP
} MemBufferMode;

// storage for partition #0 and partial data (in a rolling fashion)
typedef struct {
  MemBufferMode mode_;  // Operation mode
  size_t start_;        // start location of the data to be decoded
  size_t end_;          // end location
  size_t buf_size_;     // size of the allocated buffer
  uint8_t* buf_;        // We don't own this buffer in case WebPIUpdate()

  size_t part0_size_;         // size of partition #0
  const uint8_t* part0_buf_;  // buffer to store partition #0
} MemBuffer;

struct WebPIDecoder {
  DecState state_;         // current decoding state
  WebPDecParams params_;   // Params to store output info
  int is_lossless_;        // for down-casting 'dec_'.
  void* dec_;              // either a VP8Decoder or a VP8LDecoder instance
  VP8Io io_;

  MemBuffer mem_;          // input memory buffer.
  WebPDecBuffer output_;   // output buffer (when no external one is supplied)
  size_t chunk_size_;      // Compressed VP8/VP8L size extracted from Header.
};

// MB context to restore in case VP8DecodeMB() fails
typedef struct {
  VP8MB left_;
  VP8MB info_;
  uint8_t intra_t_[4];
  uint8_t intra_l_[4];
  VP8BitReader br_;
  VP8BitReader token_br_;
} MBContext;

//------------------------------------------------------------------------------
// MemBuffer: incoming data handling

static void RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) {
  if (br->buf_ != NULL) {
    br->buf_ += offset;
    br->buf_end_ += offset;
  }
}

static WEBP_INLINE size_t MemDataSize(const MemBuffer* mem) {
  return (mem->end_ - mem->start_);
}

// Check if we need to preserve the compressed alpha data, as it may not have
// been decoded yet.
static int NeedCompressedAlpha(const WebPIDecoder* const idec) {
  if (idec->state_ == STATE_PRE_VP8) {
    // We haven't parsed the headers yet, so we don't know whether the image is
    // lossy or lossless. This also means that we haven't parsed the ALPH chunk.
    return 0;
  }
  if (idec->is_lossless_) {
    return 0;  // ALPH chunk is not present for lossless images.
  } else {
    const VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
    assert(dec != NULL);  // Must be true as idec->state_ != STATE_PRE_VP8.
    return (dec->alpha_data_ != NULL) && !dec->is_alpha_decoded_;
  }
}

static void DoRemap(WebPIDecoder* const idec, ptrdiff_t offset) {
  MemBuffer* const mem = &idec->mem_;
  const uint8_t* const new_base = mem->buf_ + mem->start_;
  // note: for VP8, setting up idec->io_ is only really needed at the beginning
  // of the decoding, till partition #0 is complete.
  idec->io_.data = new_base;
  idec->io_.data_size = MemDataSize(mem);

  if (idec->dec_ != NULL) {
    if (!idec->is_lossless_) {
      VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
      const int last_part = dec->num_parts_ - 1;
      if (offset != 0) {
        int p;
        for (p = 0; p <= last_part; ++p) {
          RemapBitReader(dec->parts_ + p, offset);
        }
        // Remap partition #0 data pointer to new offset, but only in MAP
        // mode (in APPEND mode, partition #0 is copied into a fixed memory).
        if (mem->mode_ == MEM_MODE_MAP) {
          RemapBitReader(&dec->br_, offset);
        }
      }
      assert(last_part >= 0);
      dec->parts_[last_part].buf_end_ = mem->buf_ + mem->end_;
      if (NeedCompressedAlpha(idec)) dec->alpha_data_ += offset;
    } else {    // Resize lossless bitreader
      VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
      VP8LBitReaderSetBuffer(&dec->br_, new_base, MemDataSize(mem));
    }
  }
}

// Appends data to the end of MemBuffer->buf_. It expands the allocated memory
// size if required and also updates VP8BitReader's if new memory is allocated.
static int AppendToMemBuffer(WebPIDecoder* const idec,
                             const uint8_t* const data, size_t data_size) {
  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
  MemBuffer* const mem = &idec->mem_;
  const int need_compressed_alpha = NeedCompressedAlpha(idec);
  const uint8_t* const old_start = mem->buf_ + mem->start_;
  const uint8_t* const old_base =
      need_compressed_alpha ? dec->alpha_data_ : old_start;
  assert(mem->mode_ == MEM_MODE_APPEND);
  if (data_size > MAX_CHUNK_PAYLOAD) {
    // security safeguard: trying to allocate more than what the format
    // allows for a chunk should be considered a smoke smell.
    return 0;
  }

  if (mem->end_ + data_size > mem->buf_size_) {  // Need some free memory
    const size_t new_mem_start = old_start - old_base;
    const size_t current_size = MemDataSize(mem) + new_mem_start;
    const uint64_t new_size = (uint64_t)current_size + data_size;
    const uint64_t extra_size = (new_size + CHUNK_SIZE - 1) & ~(CHUNK_SIZE - 1);
    uint8_t* const new_buf =
        (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_ = new_mem_start;
    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_start);
  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_buf = mem->buf_;
  const uint8_t* const old_start = old_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_start);
  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;

  headers.data = data;
  headers.data_size = curr_size;
  status = WebPParseHeaders(&headers);
  if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
    return VP8_STATUS_SUSPENDED;  // We haven't found a VP8 chunk yet.
  } else if (status != VP8_STATUS_OK) {
    return IDecError(idec, status);
  }

  idec->chunk_size_ = headers.compressed_size;
  idec->is_lossless_ = headers.is_lossless;
  if (!idec->is_lossless_) {
    VP8Decoder* const dec = VP8New();
    if (dec == NULL) {
      return VP8_STATUS_OUT_OF_MEMORY;
    }
    idec->dec_ = dec;
#ifdef WEBP_USE_THREAD
    dec->use_threads_ = (idec->params_.options != NULL) &&
                        (idec->params_.options->use_threads > 0);
#else
    dec->use_threads_ = 0;
#endif
    dec->alpha_data_ = headers.alpha_data;
    dec->alpha_data_size_ = headers.alpha_data_size;
    ChangeState(idec, STATE_VP8_FRAME_HEADER, headers.offset);
  } else {
    VP8LDecoder* const dec = VP8LNew();
    if (dec == NULL) {
      return VP8_STATUS_OUT_OF_MEMORY;
    }
    idec->dec_ = dec;
    ChangeState(idec, STATE_VP8L_HEADER, headers.offset);
  }
  return VP8_STATUS_OK;
}

static VP8StatusCode DecodeVP8FrameHeader(WebPIDecoder* const idec) {
  const uint8_t* data = idec->mem_.buf_ + idec->mem_.start_;
  const size_t curr_size = MemDataSize(&idec->mem_);
  uint32_t bits;

  if (curr_size < VP8_FRAME_HEADER_SIZE) {
    // Not enough data bytes to extract VP8 Frame Header.
    return VP8_STATUS_SUSPENDED;
  }
  if (!VP8GetInfo(data, curr_size, idec->chunk_size_, NULL, NULL)) {
    return IDecError(idec, VP8_STATUS_BITSTREAM_ERROR);
  }

  bits = data[0] | (data[1] << 8) | (data[2] << 16);
  idec->mem_.part0_size_ = (bits >> 5) + VP8_FRAME_HEADER_SIZE;

  idec->io_.data = data;
  idec->io_.data_size = curr_size;
  idec->state_ = STATE_VP8_PARTS0;
  return VP8_STATUS_OK;
}

// Partition #0
static int CopyParts0Data(WebPIDecoder* const idec) {
  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
  VP8BitReader* const br = &dec->br_;
  const size_t psize = br->buf_end_ - br->buf_;
  MemBuffer* const mem = &idec->mem_;
  assert(!idec->is_lossless_);
  assert(mem->part0_buf_ == NULL);
  assert(psize > 0);
  assert(psize <= mem->part0_size_);  // Format limit: no need for runtime check
  if (mem->mode_ == MEM_MODE_APPEND) {
    // We copy and grab ownership of the partition #0 data.
    uint8_t* const part0_buf = (uint8_t*)malloc(psize);
    if (part0_buf == NULL) {
      return 0;
    }
    memcpy(part0_buf, br->buf_, psize);
    mem->part0_buf_ = part0_buf;
    br->buf_ = part0_buf;
    br->buf_end_ = part0_buf + psize;
  } else {
    // Else: just keep pointers to the partition #0's data in dec_->br_.
  }
  mem->start_ += psize;
  return 1;
}

static VP8StatusCode DecodePartition0(WebPIDecoder* const idec) {
  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
  VP8Io* const io = &idec->io_;
  const WebPDecParams* const params = &idec->params_;
  WebPDecBuffer* const output = params->output;

  // Wait till we have enough data for the whole partition #0
  if (MemDataSize(&idec->mem_) < idec->mem_.part0_size_) {
    return VP8_STATUS_SUSPENDED;
  }

  if (!VP8GetHeaders(dec, io)) {
    const VP8StatusCode status = dec->status_;
    if (status == VP8_STATUS_SUSPENDED ||
        status == VP8_STATUS_NOT_ENOUGH_DATA) {
      // treating NOT_ENOUGH_DATA as SUSPENDED state
      return VP8_STATUS_SUSPENDED;
    }
    return IDecError(idec, 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_);
  }

  if (!CopyParts0Data(idec)) {
    return IDecError(idec, VP8_STATUS_OUT_OF_MEMORY);
  }

  // Finish setting up the decoding parameters. Will call io->setup().
  if (VP8EnterCritical(dec, io) != VP8_STATUS_OK) {
    return IDecError(idec, dec->status_);
  }

  // Note: past this point, teardown() must always be called
  // in case of error.
  idec->state_ = STATE_VP8_DATA;
  // Allocate memory and prepare everything.
  if (!VP8InitFrame(dec, io)) {
    return IDecError(idec, dec->status_);
  }
  return VP8_STATUS_OK;
}

// Remaining partitions
static VP8StatusCode DecodeRemaining(WebPIDecoder* const idec) {
  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
  VP8Io* const io = &idec->io_;

  assert(dec->ready_);

  for (; dec->mb_y_ < dec->mb_h_; ++dec->mb_y_) {
    VP8BitReader* token_br = &dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
    if (dec->mb_x_ == 0) {
      VP8InitScanline(dec);
    }
    for (; dec->mb_x_ < dec->mb_w_;  dec->mb_x_++) {
      MBContext context;
      SaveContext(dec, token_br, &context);

      if (!VP8DecodeMB(dec, token_br)) {
        RestoreContext(&context, 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);
        }
        return VP8_STATUS_SUSPENDED;
      }
      // Reconstruct and emit samples.
      VP8ReconstructBlock(dec);

      // 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_);
      }
    }
    if (!VP8ProcessRow(dec, io)) {
      return IDecError(idec, VP8_STATUS_USER_ABORT);
    }
    dec->mb_x_ = 0;
  }
  // Synchronize the thread and check for errors.
  if (!VP8ExitCritical(dec, io)) {
    return IDecError(idec, VP8_STATUS_USER_ABORT);
  }
  dec->ready_ = 0;
  idec->state_ = STATE_DONE;

  return VP8_STATUS_OK;
}

static int 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)) {
    return VP8_STATUS_SUSPENDED;
  }
  if (!VP8LDecodeHeader(dec, io)) {
    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_);

  // At present Lossless decoder can't decode image incrementally. So wait till
  // all the image data is aggregated before image can be decoded.
  if (curr_size < idec->chunk_size_) {
    return VP8_STATUS_SUSPENDED;
  }

  if (!VP8LDecodeImage(dec)) {
    return ErrorStatusLossless(idec, dec->status_);
  }

  idec->state_ = STATE_DONE;

  return VP8_STATUS_OK;
}

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

  if (idec->state_ == STATE_PRE_VP8) {
    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_FRAME_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*)calloc(1, sizeof(*idec));
  if (idec == NULL) {
    return NULL;
  }

  idec->state_ = STATE_PRE_VP8;
  idec->chunk_size_ = 0;

  InitMemBuffer(&idec->mem_);
  WebPInitDecBuffer(&idec->output_);
  VP8InitIo(&idec->io_);

  WebPResetDecParams(&idec->params_);
  idec->params_.output = output_buffer ? output_buffer : &idec->output_;
  WebPInitCustomIo(&idec->params_, &idec->io_);  // Plug the I/O functions.

  return idec;
}

WebPIDecoder* WebPIDecode(const uint8_t* data, size_t data_size,
                          WebPDecoderConfig* config) {
  WebPIDecoder* idec;

  // Parse the bitstream's features, if requested:
  if (data != NULL && data_size > 0 && config != NULL) {
    if (WebPGetFeatures(data, data_size, &config->input) != VP8_STATUS_OK) {
      return NULL;
    }
  }
  // Create an instance of the incremental decoder
  idec = WebPINewDecoder(config ? &config->output : NULL);
  if (idec == NULL) {
    return NULL;
  }
  // Finish initialization
  if (config != NULL) {
    idec->params_.options = &config->options;
  }
  return idec;
}

void WebPIDelete(WebPIDecoder* idec) {
  if (idec == NULL) return;
  if (idec->dec_ != NULL) {
    if (!idec->is_lossless_) {
      VP8Delete(idec->dec_);
    } else {
      VP8LDelete(idec->dec_);
    }
  }
  ClearMemBuffer(&idec->mem_);
  WebPFreeDecBuffer(&idec->output_);
  free(idec);
}

//------------------------------------------------------------------------------
// Wrapper toward WebPINewDecoder

WebPIDecoder* WebPINewRGB(WEBP_CSP_MODE mode, uint8_t* output_buffer,
                          size_t output_buffer_size, int output_stride) {
  const int is_external_memory = (output_buffer != NULL);
  WebPIDecoder* idec;

  if (mode >= MODE_YUV) return NULL;
  if (!is_external_memory) {    // Overwrite parameters to sane values.
    output_buffer_size = 0;
    output_stride = 0;
  } else {  // A buffer was passed. Validate the other params.
    if (output_stride == 0 || output_buffer_size == 0) {
      return NULL;   // invalid parameter.
    }
  }
  idec = WebPINewDecoder(NULL);
  if (idec == NULL) return NULL;
  idec->output_.colorspace = mode;
  idec->output_.is_external_memory = is_external_memory;
  idec->output_.u.RGBA.rgba = output_buffer;
  idec->output_.u.RGBA.stride = output_stride;
  idec->output_.u.RGBA.size = output_buffer_size;
  return idec;
}

WebPIDecoder* WebPINewYUVA(uint8_t* luma, size_t luma_size, int luma_stride,
                           uint8_t* u, size_t u_size, int u_stride,
                           uint8_t* v, size_t v_size, int v_stride,
                           uint8_t* a, size_t a_size, int a_stride) {
  const int is_external_memory = (luma != NULL);
  WebPIDecoder* idec;
  WEBP_CSP_MODE colorspace;

  if (!is_external_memory) {    // Overwrite parameters to sane values.
    luma_size = u_size = v_size = a_size = 0;
    luma_stride = u_stride = v_stride = a_stride = 0;
    u = v = a = NULL;
    colorspace = MODE_YUVA;
  } else {  // A luma buffer was passed. Validate the other parameters.
    if (u == NULL || v == NULL) return NULL;
    if (luma_size == 0 || u_size == 0 || v_size == 0) return NULL;
    if (luma_stride == 0 || u_stride == 0 || v_stride == 0) return NULL;
    if (a != NULL) {
      if (a_size == 0 || a_stride == 0) return NULL;
    }
    colorspace = (a == NULL) ? MODE_YUV : MODE_YUVA;
  }

  idec = WebPINewDecoder(NULL);
  if (idec == NULL) return NULL;

  idec->output_.colorspace = colorspace;
  idec->output_.is_external_memory = is_external_memory;
  idec->output_.u.YUVA.y = luma;
  idec->output_.u.YUVA.y_stride = luma_stride;
  idec->output_.u.YUVA.y_size = luma_size;
  idec->output_.u.YUVA.u = u;
  idec->output_.u.YUVA.u_stride = u_stride;
  idec->output_.u.YUVA.u_size = u_size;
  idec->output_.u.YUVA.v = v;
  idec->output_.u.YUVA.v_stride = v_stride;
  idec->output_.u.YUVA.v_size = v_size;
  idec->output_.u.YUVA.a = a;
  idec->output_.u.YUVA.a_stride = a_stride;
  idec->output_.u.YUVA.a_size = a_size;
  return idec;
}

WebPIDecoder* WebPINewYUV(uint8_t* luma, size_t luma_size, int luma_stride,
                          uint8_t* u, size_t u_size, int u_stride,
                          uint8_t* v, size_t v_size, int v_stride) {
  return WebPINewYUVA(luma, luma_size, luma_stride,
                      u, u_size, u_stride,
                      v, v_size, v_stride,
                      NULL, 0, 0);
}

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

static VP8StatusCode IDecCheckStatus(const WebPIDecoder* const idec) {
  assert(idec);
  if (idec->state_ == STATE_ERROR) {
    return VP8_STATUS_BITSTREAM_ERROR;
  }
  if (idec->state_ == STATE_DONE) {
    return VP8_STATUS_OK;
  }
  return VP8_STATUS_SUSPENDED;
}

VP8StatusCode WebPIAppend(WebPIDecoder* idec,
                          const uint8_t* data, size_t data_size) {
  VP8StatusCode status;
  if (idec == NULL || data == NULL) {
    return VP8_STATUS_INVALID_PARAM;
  }
  status = IDecCheckStatus(idec);
  if (status != VP8_STATUS_SUSPENDED) {
    return status;
  }
  // Check mixed calls between RemapMemBuffer and AppendToMemBuffer.
  if (!CheckMemBufferMode(&idec->mem_, MEM_MODE_APPEND)) {
    return VP8_STATUS_INVALID_PARAM;
  }
  // Append data to memory buffer
  if (!AppendToMemBuffer(idec, data, data_size)) {
    return VP8_STATUS_OUT_OF_MEMORY;
  }
  return IDecode(idec);
}

VP8StatusCode WebPIUpdate(WebPIDecoder* idec,
                          const uint8_t* data, size_t data_size) {
  VP8StatusCode status;
  if (idec == NULL || data == NULL) {
    return VP8_STATUS_INVALID_PARAM;
  }
  status = IDecCheckStatus(idec);
  if (status != VP8_STATUS_SUSPENDED) {
    return status;
  }
  // Check mixed calls between RemapMemBuffer and AppendToMemBuffer.
  if (!CheckMemBufferMode(&idec->mem_, MEM_MODE_MAP)) {
    return VP8_STATUS_INVALID_PARAM;
  }
  // Make the memory buffer point to the new buffer
  if (!RemapMemBuffer(idec, data, data_size)) {
    return VP8_STATUS_INVALID_PARAM;
  }
  return IDecode(idec);
}

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

static const WebPDecBuffer* GetOutputBuffer(const WebPIDecoder* const idec) {
  if (idec == NULL || idec->dec_ == NULL) {
    return NULL;
  }
  if (idec->state_ <= STATE_VP8_PARTS0) {
    return NULL;
  }
  return idec->params_.output;
}

const WebPDecBuffer* WebPIDecodedArea(const WebPIDecoder* idec,
                                      int* left, int* top,
                                      int* width, int* height) {
  const WebPDecBuffer* const src = GetOutputBuffer(idec);
  if (left != NULL) *left = 0;
  if (top != NULL) *top = 0;
  // TODO(skal): later include handling of rotations.
  if (src) {
    if (width != NULL) *width = src->width;
    if (height != NULL) *height = idec->params_.last_y;
  } else {
    if (width != NULL) *width = 0;
    if (height != NULL) *height = 0;
  }
  return src;
}

uint8_t* WebPIDecGetRGB(const WebPIDecoder* idec, int* last_y,
                        int* width, int* height, int* stride) {
  const WebPDecBuffer* const src = GetOutputBuffer(idec);
  if (src == NULL) return NULL;
  if (src->colorspace >= MODE_YUV) {
    return NULL;
  }

  if (last_y != NULL) *last_y = idec->params_.last_y;
  if (width != NULL) *width = src->width;
  if (height != NULL) *height = src->height;
  if (stride != NULL) *stride = src->u.RGBA.stride;

  return src->u.RGBA.rgba;
}

uint8_t* WebPIDecGetYUVA(const WebPIDecoder* idec, int* last_y,
                         uint8_t** u, uint8_t** v, uint8_t** a,
                         int* width, int* height,
                         int* stride, int* uv_stride, int* a_stride) {
  const WebPDecBuffer* const src = GetOutputBuffer(idec);
  if (src == NULL) return NULL;
  if (src->colorspace < MODE_YUV) {
    return NULL;
  }

  if (last_y != NULL) *last_y = idec->params_.last_y;
  if (u != NULL) *u = src->u.YUVA.u;
  if (v != NULL) *v = src->u.YUVA.v;
  if (a != NULL) *a = src->u.YUVA.a;
  if (width != NULL) *width = src->width;
  if (height != NULL) *height = src->height;
  if (stride != NULL) *stride = src->u.YUVA.y_stride;
  if (uv_stride != NULL) *uv_stride = src->u.YUVA.u_stride;
  if (a_stride != NULL) *a_stride = src->u.YUVA.a_stride;

  return src->u.YUVA.y;
}

int WebPISetIOHooks(WebPIDecoder* const idec,
                    VP8IoPutHook put,
                    VP8IoSetupHook setup,
                    VP8IoTeardownHook teardown,
                    void* user_data) {
  if (idec == NULL || idec->state_ > STATE_PRE_VP8) {
    return 0;
  }

  idec->io_.put = put;
  idec->io_.setup = setup;
  idec->io_.teardown = teardown;
  idec->io_.opaque = user_data;

  return 1;
}

#if defined(__cplusplus) || defined(c_plusplus)
}    // extern "C"
#endif
/* [<][>][^][v][top][bottom][index][help] */
root/3rdparty/libwebp/dec/idec.c

DEFINITIONS
