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Diffstat (limited to '')
-rw-r--r-- | third_party/jpeg-xl/lib/jxl/ans_params.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/ans_params.h b/third_party/jpeg-xl/lib/jxl/ans_params.h new file mode 100644 index 0000000000..4bbc284c0b --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/ans_params.h @@ -0,0 +1,36 @@ +// 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_ANS_PARAMS_H_ +#define LIB_JXL_ANS_PARAMS_H_ + +// Common parameters that are needed for both the ANS entropy encoding and +// decoding methods. + +#include <stdint.h> +#include <stdlib.h> + +namespace jxl { + +// TODO(veluca): decide if 12 is the best constant here (valid range is up to +// 16). This requires recomputing the Huffman tables in {enc,dec}_ans.cc +// 14 gives a 0.2% improvement at d1 and makes d8 slightly worse. This is +// likely not worth the increase in encoder complexity. +#define ANS_LOG_TAB_SIZE 12u +#define ANS_TAB_SIZE (1 << ANS_LOG_TAB_SIZE) +#define ANS_TAB_MASK (ANS_TAB_SIZE - 1) + +// Largest possible symbol to be encoded by either ANS or prefix coding. +#define PREFIX_MAX_ALPHABET_SIZE 4096 +#define ANS_MAX_ALPHABET_SIZE 256 + +// Max number of bits for prefix coding. +#define PREFIX_MAX_BITS 15 + +#define ANS_SIGNATURE 0x13 // Initial state, used as CRC. + +} // namespace jxl + +#endif // LIB_JXL_ANS_PARAMS_H_ |