diff options
Diffstat (limited to 'third_party/jpeg-xl/lib/jxl/modular/encoding/dec_ma.cc')
| -rw-r--r-- | third_party/jpeg-xl/lib/jxl/modular/encoding/dec_ma.cc | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/modular/encoding/dec_ma.cc b/third_party/jpeg-xl/lib/jxl/modular/encoding/dec_ma.cc new file mode 100644 index 0000000000..66562f7dfd --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/modular/encoding/dec_ma.cc @@ -0,0 +1,107 @@ +// 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/modular/encoding/dec_ma.h" + +#include "lib/jxl/base/printf_macros.h" +#include "lib/jxl/dec_ans.h" +#include "lib/jxl/modular/encoding/ma_common.h" +#include "lib/jxl/modular/modular_image.h" + +namespace jxl { + +namespace { + +Status ValidateTree( + const Tree &tree, + const std::vector<std::pair<pixel_type, pixel_type>> &prop_bounds, + size_t root) { + if (tree[root].property == -1) return true; + size_t p = tree[root].property; + int val = tree[root].splitval; + if (prop_bounds[p].first > val) return JXL_FAILURE("Invalid tree"); + // Splitting at max value makes no sense: left range will be exactly same + // as parent, right range will be invalid (min > max). + if (prop_bounds[p].second <= val) return JXL_FAILURE("Invalid tree"); + auto new_bounds = prop_bounds; + new_bounds[p].first = val + 1; + JXL_RETURN_IF_ERROR(ValidateTree(tree, new_bounds, tree[root].lchild)); + new_bounds[p] = prop_bounds[p]; + new_bounds[p].second = val; + return ValidateTree(tree, new_bounds, tree[root].rchild); +} + +Status DecodeTree(BitReader *br, ANSSymbolReader *reader, + const std::vector<uint8_t> &context_map, Tree *tree, + size_t tree_size_limit) { + size_t leaf_id = 0; + size_t to_decode = 1; + tree->clear(); + while (to_decode > 0) { + JXL_RETURN_IF_ERROR(br->AllReadsWithinBounds()); + if (tree->size() > tree_size_limit) { + return JXL_FAILURE("Tree is too large: %" PRIuS " nodes vs %" PRIuS + " max nodes", + tree->size(), tree_size_limit); + } + to_decode--; + uint32_t prop1 = reader->ReadHybridUint(kPropertyContext, br, context_map); + if (prop1 > 256) return JXL_FAILURE("Invalid tree property value"); + int property = prop1 - 1; + if (property == -1) { + size_t predictor = + reader->ReadHybridUint(kPredictorContext, br, context_map); + if (predictor >= kNumModularPredictors) { + return JXL_FAILURE("Invalid predictor"); + } + int64_t predictor_offset = + UnpackSigned(reader->ReadHybridUint(kOffsetContext, br, context_map)); + uint32_t mul_log = + reader->ReadHybridUint(kMultiplierLogContext, br, context_map); + if (mul_log >= 31) { + return JXL_FAILURE("Invalid multiplier logarithm"); + } + uint32_t mul_bits = + reader->ReadHybridUint(kMultiplierBitsContext, br, context_map); + if (mul_bits + 1 >= 1u << (31u - mul_log)) { + return JXL_FAILURE("Invalid multiplier"); + } + uint32_t multiplier = (mul_bits + 1U) << mul_log; + tree->emplace_back(-1, 0, leaf_id++, 0, static_cast<Predictor>(predictor), + predictor_offset, multiplier); + continue; + } + int splitval = + UnpackSigned(reader->ReadHybridUint(kSplitValContext, br, context_map)); + tree->emplace_back(property, splitval, tree->size() + to_decode + 1, + tree->size() + to_decode + 2, Predictor::Zero, 0, 1); + to_decode += 2; + } + std::vector<std::pair<pixel_type, pixel_type>> prop_bounds; + prop_bounds.resize(256, {std::numeric_limits<pixel_type>::min(), + std::numeric_limits<pixel_type>::max()}); + return ValidateTree(*tree, prop_bounds, 0); +} +} // namespace + +Status DecodeTree(BitReader *br, Tree *tree, size_t tree_size_limit) { + std::vector<uint8_t> tree_context_map; + ANSCode tree_code; + JXL_RETURN_IF_ERROR( + DecodeHistograms(br, kNumTreeContexts, &tree_code, &tree_context_map)); + // TODO(eustas): investigate more infinite tree cases. + if (tree_code.degenerate_symbols[tree_context_map[kPropertyContext]] > 0) { + return JXL_FAILURE("Infinite tree"); + } + ANSSymbolReader reader(&tree_code, br); + JXL_RETURN_IF_ERROR(DecodeTree(br, &reader, tree_context_map, tree, + std::min(tree_size_limit, kMaxTreeSize))); + if (!reader.CheckANSFinalState()) { + return JXL_FAILURE("ANS decode final state failed"); + } + return true; +} + +} // namespace jxl |