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_H_
16#define WEBP_DEC_VP8LI_H_
17
18#include <string.h>     // for memcpy()
19#include "./webpi.h"
20#include "../utils/bit_reader.h"
21#include "../utils/color_cache.h"
22#include "../utils/huffman.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
47  int             huffman_mask_;
48  int             huffman_subsample_bits_;
49  int             huffman_xsize_;
50  uint32_t       *huffman_image_;
51  int             num_htree_groups_;
52  HTreeGroup     *htree_groups_;
53} VP8LMetadata;
54
55typedef struct VP8LDecoder VP8LDecoder;
56struct VP8LDecoder {
57  VP8StatusCode    status_;
58  VP8LDecodeState  action_;
59  VP8LDecodeState  state_;
60  VP8Io           *io_;
61
62  const WebPDecBuffer *output_;    // shortcut to io->opaque->output
63
64  uint32_t        *pixels_;        // Internal data: either uint8_t* for alpha
65                                   // or uint32_t* for BGRA.
66  uint32_t        *argb_cache_;    // Scratch buffer for temporary BGRA storage.
67
68  VP8LBitReader    br_;
69
70  int              width_;
71  int              height_;
72  int              last_row_;      // last input row decoded so far.
73  int              last_pixel_;    // last pixel decoded so far. However, it may
74                                   // not be transformed, scaled and
75                                   // color-converted yet.
76  int              last_out_row_;  // last row output so far.
77
78  VP8LMetadata     hdr_;
79
80  int              next_transform_;
81  VP8LTransform    transforms_[NUM_TRANSFORMS];
82  // or'd bitset storing the transforms types.
83  uint32_t         transforms_seen_;
84
85  uint8_t         *rescaler_memory;  // Working memory for rescaling work.
86  WebPRescaler    *rescaler;         // Common rescaler for all channels.
87};
88
89//------------------------------------------------------------------------------
90// internal functions. Not public.
91
92struct ALPHDecoder;  // Defined in dec/alphai.h.
93
94// in vp8l.c
95
96// Decodes image header for alpha data stored using lossless compression.
97// Returns false in case of error.
98int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec,
99                          const uint8_t* const data, size_t data_size,
100                          uint8_t* const output);
101
102// Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are
103// already decoded in previous call(s), it will resume decoding from where it
104// was paused.
105// Returns false in case of bitstream error.
106int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec,
107                               int last_row);
108
109// Allocates and initialize a new lossless decoder instance.
110VP8LDecoder* VP8LNew(void);
111
112// Decodes the image header. Returns false in case of error.
113int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io);
114
115// Decodes an image. It's required to decode the lossless header before calling
116// this function. Returns false in case of error, with updated dec->status_.
117int VP8LDecodeImage(VP8LDecoder* const dec);
118
119// Resets the decoder in its initial state, reclaiming memory.
120// Preserves the dec->status_ value.
121void VP8LClear(VP8LDecoder* const dec);
122
123// Clears and deallocate a lossless decoder instance.
124void VP8LDelete(VP8LDecoder* const dec);
125
126//------------------------------------------------------------------------------
127
128#ifdef __cplusplus
129}    // extern "C"
130#endif
131
132#endif  /* WEBP_DEC_VP8LI_H_ */
133