blob: 5dc101b36fcb8ee7d37c89c37cb4b294835973e7 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/jxl/entropy_coder.h"
#include <stddef.h>
#include <stdint.h>
#include <algorithm>
#include <utility>
#include <vector>
#include "lib/jxl/ac_context.h"
#include "lib/jxl/ac_strategy.h"
#include "lib/jxl/base/bits.h"
#include "lib/jxl/base/compiler_specific.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/coeff_order.h"
#include "lib/jxl/coeff_order_fwd.h"
#include "lib/jxl/dec_ans.h"
#include "lib/jxl/dec_bit_reader.h"
#include "lib/jxl/dec_context_map.h"
#include "lib/jxl/epf.h"
#include "lib/jxl/image.h"
#include "lib/jxl/image_ops.h"
#include "lib/jxl/pack_signed.h"
namespace jxl {
Status DecodeBlockCtxMap(BitReader* br, BlockCtxMap* block_ctx_map) {
auto& dct = block_ctx_map->dc_thresholds;
auto& qft = block_ctx_map->qf_thresholds;
auto& ctx_map = block_ctx_map->ctx_map;
bool is_default = static_cast<bool>(br->ReadFixedBits<1>());
if (is_default) {
*block_ctx_map = BlockCtxMap();
return true;
}
block_ctx_map->num_dc_ctxs = 1;
for (int j : {0, 1, 2}) {
dct[j].resize(br->ReadFixedBits<4>());
block_ctx_map->num_dc_ctxs *= dct[j].size() + 1;
for (int& i : dct[j]) {
i = UnpackSigned(U32Coder::Read(kDCThresholdDist, br));
}
}
qft.resize(br->ReadFixedBits<4>());
for (uint32_t& i : qft) {
i = U32Coder::Read(kQFThresholdDist, br) + 1;
}
if (block_ctx_map->num_dc_ctxs * (qft.size() + 1) > 64) {
return JXL_FAILURE("Invalid block context map: too big");
}
ctx_map.resize(3 * kNumOrders * block_ctx_map->num_dc_ctxs *
(qft.size() + 1));
JXL_RETURN_IF_ERROR(DecodeContextMap(&ctx_map, &block_ctx_map->num_ctxs, br));
if (block_ctx_map->num_ctxs > 16) {
return JXL_FAILURE("Invalid block context map: too many distinct contexts");
}
return true;
}
constexpr uint8_t BlockCtxMap::kDefaultCtxMap[]; // from ac_context.h
} // namespace jxl
|
