1// Copyright 2012 Google Inc. All Rights Reserved.
2//
3// Use of this source code is governed by a BSD-style license
4// that can be found in the COPYING file in the root of the source
5// tree. An additional intellectual property rights grant can be found
6// in the file PATENTS. All contributing project authors may
7// be found in the AUTHORS file in the root of the source tree.
8// -----------------------------------------------------------------------------
9//
10// Lossless decoder: internal header.
11//
12// Author: Skal (pascal.massimino@gmail.com)
13// Vikas Arora(vikaas.arora@gmail.com)
14
15#ifndef WEBP_DEC_VP8LI_DEC_H_
16#define WEBP_DEC_VP8LI_DEC_H_
17
18#include <string.h> // for memcpy()
19#include "src/dec/webpi_dec.h"
20#include "src/utils/bit_reader_utils.h"
21#include "src/utils/color_cache_utils.h"
22#include "src/utils/huffman_utils.h"
23
24#ifdef __cplusplus
25extern "C" {
26#endif
27
28typedef enum {
29 READ_DATA = 0,
30 READ_HDR = 1,
31 READ_DIM = 2
32} VP8LDecodeState;
33
34typedef struct VP8LTransform VP8LTransform;
35struct VP8LTransform {
36 VP8LImageTransformType type_; // transform type.
37 int bits_; // subsampling bits defining transform window.
38 int xsize_; // transform window X index.
39 int ysize_; // transform window Y index.
40 uint32_t* data_; // transform data.
41};
42
43typedef struct {
44 int color_cache_size_;
45 VP8LColorCache color_cache_;
46 VP8LColorCache saved_color_cache_; // for incremental
47
48 int huffman_mask_;
49 int huffman_subsample_bits_;
50 int huffman_xsize_;
51 uint32_t* huffman_image_;
52 int num_htree_groups_;
53 HTreeGroup* htree_groups_;
54 HuffmanCode* huffman_tables_;
55} VP8LMetadata;
56
57typedef struct VP8LDecoder VP8LDecoder;
58struct VP8LDecoder {
59 VP8StatusCode status_;
60 VP8LDecodeState state_;
61 VP8Io* io_;
62
63 const WebPDecBuffer* output_; // shortcut to io->opaque->output
64
65 uint32_t* pixels_; // Internal data: either uint8_t* for alpha
66 // or uint32_t* for BGRA.
67 uint32_t* argb_cache_; // Scratch buffer for temporary BGRA storage.
68
69 VP8LBitReader br_;
70 int incremental_; // if true, incremental decoding is expected
71 VP8LBitReader saved_br_; // note: could be local variables too
72 int saved_last_pixel_;
73
74 int width_;
75 int height_;
76 int last_row_; // last input row decoded so far.
77 int last_pixel_; // last pixel decoded so far. However, it may
78 // not be transformed, scaled and
79 // color-converted yet.
80 int last_out_row_; // last row output so far.
81
82 VP8LMetadata hdr_;
83
84 int next_transform_;
85 VP8LTransform transforms_[NUM_TRANSFORMS];
86 // or'd bitset storing the transforms types.
87 uint32_t transforms_seen_;
88
89 uint8_t* rescaler_memory; // Working memory for rescaling work.
90 WebPRescaler* rescaler; // Common rescaler for all channels.
91};
92
93//------------------------------------------------------------------------------
94// internal functions. Not public.
95
96struct ALPHDecoder; // Defined in dec/alphai.h.
97
98// in vp8l.c
99
100// Decodes image header for alpha data stored using lossless compression.
101// Returns false in case of error.
102int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec,
103 const uint8_t* const data, size_t data_size);
104
105// Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are
106// already decoded in previous call(s), it will resume decoding from where it
107// was paused.
108// Returns false in case of bitstream error.
109int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec,
110 int last_row);
111
112// Allocates and initialize a new lossless decoder instance.
113VP8LDecoder* VP8LNew(void);
114
115// Decodes the image header. Returns false in case of error.
116int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io);
117
118// Decodes an image. It's required to decode the lossless header before calling
119// this function. Returns false in case of error, with updated dec->status_.
120int VP8LDecodeImage(VP8LDecoder* const dec);
121
122// Resets the decoder in its initial state, reclaiming memory.
123// Preserves the dec->status_ value.
124void VP8LClear(VP8LDecoder* const dec);
125
126// Clears and deallocate a lossless decoder instance.
127void VP8LDelete(VP8LDecoder* const dec);
128
129//------------------------------------------------------------------------------
130
131#ifdef __cplusplus
132} // extern "C"
133#endif
134
135#endif // WEBP_DEC_VP8LI_DEC_H_
136