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Diffstat (limited to 'third_party/jpeg-xl/lib/jxl/ac_strategy.h')
| -rw-r--r-- | third_party/jpeg-xl/lib/jxl/ac_strategy.h | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/ac_strategy.h b/third_party/jpeg-xl/lib/jxl/ac_strategy.h new file mode 100644 index 0000000000..7d21167e6e --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/ac_strategy.h @@ -0,0 +1,261 @@ +// 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. + +#ifndef LIB_JXL_AC_STRATEGY_H_ +#define LIB_JXL_AC_STRATEGY_H_ + +#include <stddef.h> +#include <stdint.h> + +#include <hwy/base.h> // kMaxVectorSize + +#include "lib/jxl/base/status.h" +#include "lib/jxl/coeff_order_fwd.h" +#include "lib/jxl/common.h" +#include "lib/jxl/image_ops.h" + +// Defines the different kinds of transforms, and heuristics to choose between +// them. +// `AcStrategy` represents what transform should be used, and which sub-block of +// that transform we are currently in. Note that DCT4x4 is applied on all four +// 4x4 sub-blocks of an 8x8 block. +// `AcStrategyImage` defines which strategy should be used for each 8x8 block +// of the image. The highest 4 bits represent the strategy to be used, the +// lowest 4 represent the index of the block inside that strategy. + +namespace jxl { + +class AcStrategy { + public: + // Extremal values for the number of blocks/coefficients of a single strategy. + static constexpr size_t kMaxCoeffBlocks = 32; + static constexpr size_t kMaxBlockDim = kBlockDim * kMaxCoeffBlocks; + // Maximum number of coefficients in a block. Guaranteed to be a multiple of + // the vector size. + static constexpr size_t kMaxCoeffArea = kMaxBlockDim * kMaxBlockDim; + static_assert((kMaxCoeffArea * sizeof(float)) % hwy::kMaxVectorSize == 0, + "Coefficient area is not a multiple of vector size"); + + // Raw strategy types. + enum Type : uint32_t { + // Regular block size DCT + DCT = 0, + // Encode pixels without transforming + IDENTITY = 1, + // Use 2-by-2 DCT + DCT2X2 = 2, + // Use 4-by-4 DCT + DCT4X4 = 3, + // Use 16-by-16 DCT + DCT16X16 = 4, + // Use 32-by-32 DCT + DCT32X32 = 5, + // Use 16-by-8 DCT + DCT16X8 = 6, + // Use 8-by-16 DCT + DCT8X16 = 7, + // Use 32-by-8 DCT + DCT32X8 = 8, + // Use 8-by-32 DCT + DCT8X32 = 9, + // Use 32-by-16 DCT + DCT32X16 = 10, + // Use 16-by-32 DCT + DCT16X32 = 11, + // 4x8 and 8x4 DCT + DCT4X8 = 12, + DCT8X4 = 13, + // Corner-DCT. + AFV0 = 14, + AFV1 = 15, + AFV2 = 16, + AFV3 = 17, + // Larger DCTs + DCT64X64 = 18, + DCT64X32 = 19, + DCT32X64 = 20, + DCT128X128 = 21, + DCT128X64 = 22, + DCT64X128 = 23, + DCT256X256 = 24, + DCT256X128 = 25, + DCT128X256 = 26, + // Marker for num of valid strategies. + kNumValidStrategies + }; + + static constexpr uint32_t TypeBit(const Type type) { + return 1u << static_cast<uint32_t>(type); + } + + // Returns true if this block is the first 8x8 block (i.e. top-left) of a + // possibly multi-block strategy. + JXL_INLINE bool IsFirstBlock() const { return is_first_; } + + JXL_INLINE bool IsMultiblock() const { + constexpr uint32_t bits = + TypeBit(Type::DCT16X16) | TypeBit(Type::DCT32X32) | + TypeBit(Type::DCT16X8) | TypeBit(Type::DCT8X16) | + TypeBit(Type::DCT32X8) | TypeBit(Type::DCT8X32) | + TypeBit(Type::DCT16X32) | TypeBit(Type::DCT32X16) | + TypeBit(Type::DCT32X64) | TypeBit(Type::DCT64X32) | + TypeBit(Type::DCT64X64) | TypeBit(DCT64X128) | TypeBit(DCT128X64) | + TypeBit(DCT128X128) | TypeBit(DCT128X256) | TypeBit(DCT256X128) | + TypeBit(DCT256X256); + JXL_DASSERT(Strategy() < kNumValidStrategies); + return ((1u << static_cast<uint32_t>(Strategy())) & bits) != 0; + } + + // Returns the raw strategy value. Should only be used for tokenization. + JXL_INLINE uint8_t RawStrategy() const { + return static_cast<uint8_t>(strategy_); + } + + JXL_INLINE Type Strategy() const { return strategy_; } + + // Inverse check + static JXL_INLINE constexpr bool IsRawStrategyValid(int raw_strategy) { + return raw_strategy < static_cast<int32_t>(kNumValidStrategies) && + raw_strategy >= 0; + } + static JXL_INLINE AcStrategy FromRawStrategy(uint8_t raw_strategy) { + return FromRawStrategy(static_cast<Type>(raw_strategy)); + } + static JXL_INLINE AcStrategy FromRawStrategy(Type raw_strategy) { + JXL_DASSERT(IsRawStrategyValid(static_cast<uint32_t>(raw_strategy))); + return AcStrategy(raw_strategy, /*is_first=*/true); + } + + // "Natural order" means the order of increasing of "anisotropic" frequency of + // continuous version of DCT basis. + // Round-trip, for any given strategy s: + // X = NaturalCoeffOrder(s)[NaturalCoeffOrderLutN(s)[X]] + // X = NaturalCoeffOrderLut(s)[NaturalCoeffOrderN(s)[X]] + void ComputeNaturalCoeffOrder(coeff_order_t* order) const; + void ComputeNaturalCoeffOrderLut(coeff_order_t* lut) const; + + // Number of 8x8 blocks that this strategy will cover. 0 for non-top-left + // blocks inside a multi-block transform. + JXL_INLINE size_t covered_blocks_x() const { + static constexpr uint8_t kLut[] = {1, 1, 1, 1, 2, 4, 1, 2, 1, + 4, 2, 4, 1, 1, 1, 1, 1, 1, + 8, 4, 8, 16, 8, 16, 32, 16, 32}; + static_assert(sizeof(kLut) / sizeof(*kLut) == kNumValidStrategies, + "Update LUT"); + return kLut[size_t(strategy_)]; + } + + JXL_INLINE size_t covered_blocks_y() const { + static constexpr uint8_t kLut[] = {1, 1, 1, 1, 2, 4, 2, 1, 4, + 1, 4, 2, 1, 1, 1, 1, 1, 1, + 8, 8, 4, 16, 16, 8, 32, 32, 16}; + static_assert(sizeof(kLut) / sizeof(*kLut) == kNumValidStrategies, + "Update LUT"); + return kLut[size_t(strategy_)]; + } + + JXL_INLINE size_t log2_covered_blocks() const { + static constexpr uint8_t kLut[] = {0, 0, 0, 0, 2, 4, 1, 1, 2, + 2, 3, 3, 0, 0, 0, 0, 0, 0, + 6, 5, 5, 8, 7, 7, 10, 9, 9}; + static_assert(sizeof(kLut) / sizeof(*kLut) == kNumValidStrategies, + "Update LUT"); + return kLut[size_t(strategy_)]; + } + + private: + friend class AcStrategyRow; + JXL_INLINE AcStrategy(Type strategy, bool is_first) + : strategy_(strategy), is_first_(is_first) { + JXL_DASSERT(IsMultiblock() || is_first == true); + } + + Type strategy_; + bool is_first_; +}; + +// Class to use a certain row of the AC strategy. +class AcStrategyRow { + public: + explicit AcStrategyRow(const uint8_t* row) : row_(row) {} + AcStrategy operator[](size_t x) const { + return AcStrategy(static_cast<AcStrategy::Type>(row_[x] >> 1), row_[x] & 1); + } + + private: + const uint8_t* JXL_RESTRICT row_; +}; + +class AcStrategyImage { + public: + AcStrategyImage() = default; + AcStrategyImage(size_t xsize, size_t ysize); + AcStrategyImage(AcStrategyImage&&) = default; + AcStrategyImage& operator=(AcStrategyImage&&) = default; + + void FillDCT8(const Rect& rect) { + FillPlane<uint8_t>((static_cast<uint8_t>(AcStrategy::Type::DCT) << 1) | 1, + &layers_, rect); + } + void FillDCT8() { FillDCT8(Rect(layers_)); } + + void FillInvalid() { FillImage(INVALID, &layers_); } + + void Set(size_t x, size_t y, AcStrategy::Type type) { +#if JXL_ENABLE_ASSERT + AcStrategy acs = AcStrategy::FromRawStrategy(type); +#endif // JXL_ENABLE_ASSERT + JXL_ASSERT(y + acs.covered_blocks_y() <= layers_.ysize()); + JXL_ASSERT(x + acs.covered_blocks_x() <= layers_.xsize()); + JXL_CHECK(SetNoBoundsCheck(x, y, type, /*check=*/false)); + } + + Status SetNoBoundsCheck(size_t x, size_t y, AcStrategy::Type type, + bool check = true) { + AcStrategy acs = AcStrategy::FromRawStrategy(type); + for (size_t iy = 0; iy < acs.covered_blocks_y(); iy++) { + for (size_t ix = 0; ix < acs.covered_blocks_x(); ix++) { + size_t pos = (y + iy) * stride_ + x + ix; + if (check && row_[pos] != INVALID) { + return JXL_FAILURE("Invalid AC strategy: block overlap"); + } + row_[pos] = + (static_cast<uint8_t>(type) << 1) | ((iy | ix) == 0 ? 1 : 0); + } + } + return true; + } + + bool IsValid(size_t x, size_t y) { return row_[y * stride_ + x] != INVALID; } + + AcStrategyRow ConstRow(size_t y, size_t x_prefix = 0) const { + return AcStrategyRow(layers_.ConstRow(y) + x_prefix); + } + + AcStrategyRow ConstRow(const Rect& rect, size_t y) const { + return ConstRow(rect.y0() + y, rect.x0()); + } + + size_t PixelsPerRow() const { return layers_.PixelsPerRow(); } + + size_t xsize() const { return layers_.xsize(); } + size_t ysize() const { return layers_.ysize(); } + + // Count the number of blocks of a given type. + size_t CountBlocks(AcStrategy::Type type) const; + + private: + ImageB layers_; + uint8_t* JXL_RESTRICT row_; + size_t stride_; + + // A value that does not represent a valid combined AC strategy + // value. Used as a sentinel. + static constexpr uint8_t INVALID = 0xFF; +}; + +} // namespace jxl + +#endif // LIB_JXL_AC_STRATEGY_H_ |