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Diffstat (limited to '')
-rw-r--r-- | third_party/jpeg-xl/lib/jxl/entropy_coder.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/entropy_coder.h b/third_party/jpeg-xl/lib/jxl/entropy_coder.h new file mode 100644 index 0000000000..e4afa7a631 --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/entropy_coder.h @@ -0,0 +1,45 @@ +// 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_ENTROPY_CODER_H_ +#define LIB_JXL_ENTROPY_CODER_H_ + +#include <stddef.h> +#include <stdint.h> + +#include "lib/jxl/ac_context.h" +#include "lib/jxl/base/compiler_specific.h" +#include "lib/jxl/dec_bit_reader.h" +#include "lib/jxl/field_encodings.h" + +// Entropy coding and context modeling of DC and AC coefficients, as well as AC +// strategy and quantization field. + +namespace jxl { + +static JXL_INLINE int32_t PredictFromTopAndLeft( + const int32_t* const JXL_RESTRICT row_top, + const int32_t* const JXL_RESTRICT row, size_t x, int32_t default_val) { + if (x == 0) { + return row_top == nullptr ? default_val : row_top[x]; + } + if (row_top == nullptr) { + return row[x - 1]; + } + return (row_top[x] + row[x - 1] + 1) / 2; +} + +static constexpr U32Enc kDCThresholdDist(Bits(4), BitsOffset(8, 16), + BitsOffset(16, 272), + BitsOffset(32, 65808)); + +static constexpr U32Enc kQFThresholdDist(Bits(2), BitsOffset(3, 4), + BitsOffset(5, 12), BitsOffset(8, 44)); + +Status DecodeBlockCtxMap(BitReader* br, BlockCtxMap* block_ctx_map); + +} // namespace jxl + +#endif // LIB_JXL_ENTROPY_CODER_H_ |