diff options
Diffstat (limited to 'third_party/jpeg-xl/lib/jxl/entropy_coder.cc')
-rw-r--r-- | third_party/jpeg-xl/lib/jxl/entropy_coder.cc | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/entropy_coder.cc b/third_party/jpeg-xl/lib/jxl/entropy_coder.cc new file mode 100644 index 0000000000..0043c2d31e --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/entropy_coder.cc @@ -0,0 +1,70 @@ +// 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/profiler.h" +#include "lib/jxl/base/status.h" +#include "lib/jxl/coeff_order.h" +#include "lib/jxl/coeff_order_fwd.h" +#include "lib/jxl/common.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" + +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 = 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 |