133 lines
4.4 KiB
C
133 lines
4.4 KiB
C
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// Copyright 2012 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Lossless decoder: internal header.
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//
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// Author: Skal (pascal.massimino@gmail.com)
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// Vikas Arora(vikaas.arora@gmail.com)
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#ifndef WEBP_DEC_VP8LI_H_
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#define WEBP_DEC_VP8LI_H_
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#include <string.h> // for memcpy()
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#include "./webpi.h"
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#include "../utils/bit_reader.h"
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#include "../utils/color_cache.h"
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#include "../utils/huffman.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef enum {
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READ_DATA = 0,
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READ_HDR = 1,
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READ_DIM = 2
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} VP8LDecodeState;
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typedef struct VP8LTransform VP8LTransform;
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struct VP8LTransform {
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VP8LImageTransformType type_; // transform type.
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int bits_; // subsampling bits defining transform window.
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int xsize_; // transform window X index.
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int ysize_; // transform window Y index.
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uint32_t *data_; // transform data.
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};
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typedef struct {
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int color_cache_size_;
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VP8LColorCache color_cache_;
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int huffman_mask_;
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int huffman_subsample_bits_;
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int huffman_xsize_;
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uint32_t *huffman_image_;
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int num_htree_groups_;
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HTreeGroup *htree_groups_;
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} VP8LMetadata;
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typedef struct VP8LDecoder VP8LDecoder;
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struct VP8LDecoder {
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VP8StatusCode status_;
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VP8LDecodeState action_;
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VP8LDecodeState state_;
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VP8Io *io_;
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const WebPDecBuffer *output_; // shortcut to io->opaque->output
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uint32_t *pixels_; // Internal data: either uint8_t* for alpha
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// or uint32_t* for BGRA.
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uint32_t *argb_cache_; // Scratch buffer for temporary BGRA storage.
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VP8LBitReader br_;
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int width_;
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int height_;
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int last_row_; // last input row decoded so far.
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int last_pixel_; // last pixel decoded so far. However, it may
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// not be transformed, scaled and
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// color-converted yet.
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int last_out_row_; // last row output so far.
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VP8LMetadata hdr_;
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int next_transform_;
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VP8LTransform transforms_[NUM_TRANSFORMS];
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// or'd bitset storing the transforms types.
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uint32_t transforms_seen_;
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uint8_t *rescaler_memory; // Working memory for rescaling work.
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WebPRescaler *rescaler; // Common rescaler for all channels.
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};
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//------------------------------------------------------------------------------
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// internal functions. Not public.
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struct ALPHDecoder; // Defined in dec/alphai.h.
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// in vp8l.c
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// Decodes image header for alpha data stored using lossless compression.
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// Returns false in case of error.
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int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec,
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const uint8_t* const data, size_t data_size,
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uint8_t* const output);
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// Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are
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// already decoded in previous call(s), it will resume decoding from where it
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// was paused.
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// Returns false in case of bitstream error.
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int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec,
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int last_row);
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// Allocates and initialize a new lossless decoder instance.
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VP8LDecoder* VP8LNew(void);
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// Decodes the image header. Returns false in case of error.
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int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io);
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// Decodes an image. It's required to decode the lossless header before calling
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// this function. Returns false in case of error, with updated dec->status_.
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int VP8LDecodeImage(VP8LDecoder* const dec);
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// Resets the decoder in its initial state, reclaiming memory.
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// Preserves the dec->status_ value.
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void VP8LClear(VP8LDecoder* const dec);
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// Clears and deallocate a lossless decoder instance.
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void VP8LDelete(VP8LDecoder* const dec);
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//------------------------------------------------------------------------------
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif /* WEBP_DEC_VP8LI_H_ */
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