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5434de01e2
fix #3328 In situations where the alphabet size is very small, the evaluation of literal costs from the Optimal Parser is initially incorrect. It takes some time to converge, during which compression is less efficient. This is especially important for small files, because there will not be enough data to converge, so most of the parsing is selected based on incorrect metrics. After this patch, the scenario ##3328 gets fixed, delivering the expected 29 bytes compressed size (smallest known compressed size).
36 lines
1.5 KiB
C
36 lines
1.5 KiB
C
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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#ifndef ZSTD_COMPRESS_LITERALS_H
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#define ZSTD_COMPRESS_LITERALS_H
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#include "zstd_compress_internal.h" /* ZSTD_hufCTables_t, ZSTD_minGain() */
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size_t ZSTD_noCompressLiterals (void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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size_t ZSTD_compressRleLiteralsBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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/* ZSTD_compressLiterals():
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* @entropyWorkspace: must be aligned on 4-bytes boundaries
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* @entropyWorkspaceSize : must be >= HUF_WORKSPACE_SIZE
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* @suspectUncompressible: sampling checks, to potentially skip huffman coding
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*/
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size_t ZSTD_compressLiterals (void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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void* entropyWorkspace, size_t entropyWorkspaceSize,
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const ZSTD_hufCTables_t* prevHuf,
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ZSTD_hufCTables_t* nextHuf,
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ZSTD_strategy strategy, int disableLiteralCompression,
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int suspectUncompressible,
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int bmi2);
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#endif /* ZSTD_COMPRESS_LITERALS_H */
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