49 lines
1.5 KiB
C++
49 lines
1.5 KiB
C++
// Copyright (c) the JPEG XL Project Authors. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#ifndef LIB_JXL_ENTROPY_CODER_H_
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#define LIB_JXL_ENTROPY_CODER_H_
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#include <jxl/memory_manager.h>
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#include <cstddef>
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#include <cstdint>
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#include "lib/jxl/ac_context.h"
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#include "lib/jxl/base/compiler_specific.h"
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#include "lib/jxl/base/status.h"
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#include "lib/jxl/dec_bit_reader.h"
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#include "lib/jxl/field_encodings.h"
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// Entropy coding and context modeling of DC and AC coefficients, as well as AC
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// strategy and quantization field.
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namespace jxl {
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static JXL_INLINE int32_t PredictFromTopAndLeft(
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const int32_t* const JXL_RESTRICT row_top,
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const int32_t* const JXL_RESTRICT row, size_t x, int32_t default_val) {
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if (x == 0) {
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return row_top == nullptr ? default_val : row_top[x];
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}
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if (row_top == nullptr) {
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return row[x - 1];
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}
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return (row_top[x] + row[x - 1] + 1) / 2;
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}
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static constexpr U32Enc kDCThresholdDist(Bits(4), BitsOffset(8, 16),
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BitsOffset(16, 272),
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BitsOffset(32, 65808));
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static constexpr U32Enc kQFThresholdDist(Bits(2), BitsOffset(3, 4),
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BitsOffset(5, 12), BitsOffset(8, 44));
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Status DecodeBlockCtxMap(JxlMemoryManager* memory_manager, BitReader* br,
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BlockCtxMap* block_ctx_map);
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} // namespace jxl
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#endif // LIB_JXL_ENTROPY_CODER_H_
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