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447 lines
17 KiB
447 lines
17 KiB
/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */ |
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/* |
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* Copyright (c) Yann Collet, Facebook, Inc. |
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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 https://github.com/facebook/zstd) and |
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* the GPLv2 (found in the COPYING file in the root directory of |
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* https://github.com/facebook/zstd). You may select, at your option, one of the |
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* above-listed licenses. |
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*/ |
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#ifndef LINUX_ZSTD_H |
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#define LINUX_ZSTD_H |
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/** |
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* This is a kernel-style API that wraps the upstream zstd API, which cannot be |
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* used directly because the symbols aren't exported. It exposes the minimal |
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* functionality which is currently required by users of zstd in the kernel. |
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* Expose extra functions from lib/zstd/zstd.h as needed. |
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*/ |
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/* ====== Dependency ====== */ |
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#include <linux/types.h> |
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#include <linux/zstd_errors.h> |
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#include <linux/zstd_lib.h> |
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/* ====== Helper Functions ====== */ |
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/** |
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* zstd_compress_bound() - maximum compressed size in worst case scenario |
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* @src_size: The size of the data to compress. |
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* |
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* Return: The maximum compressed size in the worst case scenario. |
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*/ |
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size_t zstd_compress_bound(size_t src_size); |
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/** |
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* zstd_is_error() - tells if a size_t function result is an error code |
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* @code: The function result to check for error. |
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* |
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* Return: Non-zero iff the code is an error. |
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*/ |
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unsigned int zstd_is_error(size_t code); |
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/** |
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* enum zstd_error_code - zstd error codes |
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*/ |
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typedef ZSTD_ErrorCode zstd_error_code; |
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/** |
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* zstd_get_error_code() - translates an error function result to an error code |
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* @code: The function result for which zstd_is_error(code) is true. |
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* |
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* Return: A unique error code for this error. |
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*/ |
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zstd_error_code zstd_get_error_code(size_t code); |
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/** |
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* zstd_get_error_name() - translates an error function result to a string |
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* @code: The function result for which zstd_is_error(code) is true. |
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* |
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* Return: An error string corresponding to the error code. |
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*/ |
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const char *zstd_get_error_name(size_t code); |
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/** |
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* zstd_min_clevel() - minimum allowed compression level |
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* |
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* Return: The minimum allowed compression level. |
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*/ |
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int zstd_min_clevel(void); |
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/** |
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* zstd_max_clevel() - maximum allowed compression level |
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* |
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* Return: The maximum allowed compression level. |
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*/ |
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int zstd_max_clevel(void); |
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/* ====== Parameter Selection ====== */ |
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/** |
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* enum zstd_strategy - zstd compression search strategy |
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* |
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* From faster to stronger. See zstd_lib.h. |
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*/ |
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typedef ZSTD_strategy zstd_strategy; |
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/** |
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* struct zstd_compression_parameters - zstd compression parameters |
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* @windowLog: Log of the largest match distance. Larger means more |
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* compression, and more memory needed during decompression. |
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* @chainLog: Fully searched segment. Larger means more compression, |
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* slower, and more memory (useless for fast). |
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* @hashLog: Dispatch table. Larger means more compression, |
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* slower, and more memory. |
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* @searchLog: Number of searches. Larger means more compression and slower. |
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* @searchLength: Match length searched. Larger means faster decompression, |
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* sometimes less compression. |
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* @targetLength: Acceptable match size for optimal parser (only). Larger means |
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* more compression, and slower. |
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* @strategy: The zstd compression strategy. |
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* |
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* See zstd_lib.h. |
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*/ |
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typedef ZSTD_compressionParameters zstd_compression_parameters; |
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/** |
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* struct zstd_frame_parameters - zstd frame parameters |
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* @contentSizeFlag: Controls whether content size will be present in the |
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* frame header (when known). |
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* @checksumFlag: Controls whether a 32-bit checksum is generated at the |
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* end of the frame for error detection. |
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* @noDictIDFlag: Controls whether dictID will be saved into the frame |
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* header when using dictionary compression. |
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* |
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* The default value is all fields set to 0. See zstd_lib.h. |
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*/ |
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typedef ZSTD_frameParameters zstd_frame_parameters; |
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/** |
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* struct zstd_parameters - zstd parameters |
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* @cParams: The compression parameters. |
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* @fParams: The frame parameters. |
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*/ |
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typedef ZSTD_parameters zstd_parameters; |
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/** |
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* zstd_get_params() - returns zstd_parameters for selected level |
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* @level: The compression level |
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* @estimated_src_size: The estimated source size to compress or 0 |
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* if unknown. |
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* |
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* Return: The selected zstd_parameters. |
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*/ |
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zstd_parameters zstd_get_params(int level, |
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unsigned long long estimated_src_size); |
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/* ====== Single-pass Compression ====== */ |
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typedef ZSTD_CCtx zstd_cctx; |
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/** |
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* zstd_cctx_workspace_bound() - max memory needed to initialize a zstd_cctx |
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* @parameters: The compression parameters to be used. |
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* |
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* If multiple compression parameters might be used, the caller must call |
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* zstd_cctx_workspace_bound() for each set of parameters and use the maximum |
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* size. |
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* |
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* Return: A lower bound on the size of the workspace that is passed to |
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* zstd_init_cctx(). |
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*/ |
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size_t zstd_cctx_workspace_bound(const zstd_compression_parameters *parameters); |
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/** |
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* zstd_init_cctx() - initialize a zstd compression context |
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* @workspace: The workspace to emplace the context into. It must outlive |
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* the returned context. |
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* @workspace_size: The size of workspace. Use zstd_cctx_workspace_bound() to |
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* determine how large the workspace must be. |
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* |
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* Return: A zstd compression context or NULL on error. |
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*/ |
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zstd_cctx *zstd_init_cctx(void *workspace, size_t workspace_size); |
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/** |
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* zstd_compress_cctx() - compress src into dst with the initialized parameters |
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* @cctx: The context. Must have been initialized with zstd_init_cctx(). |
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* @dst: The buffer to compress src into. |
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* @dst_capacity: The size of the destination buffer. May be any size, but |
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* ZSTD_compressBound(srcSize) is guaranteed to be large enough. |
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* @src: The data to compress. |
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* @src_size: The size of the data to compress. |
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* @parameters: The compression parameters to be used. |
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* |
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* Return: The compressed size or an error, which can be checked using |
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* zstd_is_error(). |
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*/ |
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size_t zstd_compress_cctx(zstd_cctx *cctx, void *dst, size_t dst_capacity, |
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const void *src, size_t src_size, const zstd_parameters *parameters); |
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/* ====== Single-pass Decompression ====== */ |
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typedef ZSTD_DCtx zstd_dctx; |
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/** |
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* zstd_dctx_workspace_bound() - max memory needed to initialize a zstd_dctx |
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* |
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* Return: A lower bound on the size of the workspace that is passed to |
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* zstd_init_dctx(). |
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*/ |
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size_t zstd_dctx_workspace_bound(void); |
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/** |
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* zstd_init_dctx() - initialize a zstd decompression context |
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* @workspace: The workspace to emplace the context into. It must outlive |
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* the returned context. |
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* @workspace_size: The size of workspace. Use zstd_dctx_workspace_bound() to |
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* determine how large the workspace must be. |
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* |
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* Return: A zstd decompression context or NULL on error. |
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*/ |
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zstd_dctx *zstd_init_dctx(void *workspace, size_t workspace_size); |
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/** |
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* zstd_decompress_dctx() - decompress zstd compressed src into dst |
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* @dctx: The decompression context. |
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* @dst: The buffer to decompress src into. |
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* @dst_capacity: The size of the destination buffer. Must be at least as large |
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* as the decompressed size. If the caller cannot upper bound the |
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* decompressed size, then it's better to use the streaming API. |
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* @src: The zstd compressed data to decompress. Multiple concatenated |
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* frames and skippable frames are allowed. |
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* @src_size: The exact size of the data to decompress. |
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* |
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* Return: The decompressed size or an error, which can be checked using |
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* zstd_is_error(). |
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*/ |
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size_t zstd_decompress_dctx(zstd_dctx *dctx, void *dst, size_t dst_capacity, |
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const void *src, size_t src_size); |
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/* ====== Streaming Buffers ====== */ |
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/** |
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* struct zstd_in_buffer - input buffer for streaming |
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* @src: Start of the input buffer. |
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* @size: Size of the input buffer. |
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* @pos: Position where reading stopped. Will be updated. |
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* Necessarily 0 <= pos <= size. |
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* |
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* See zstd_lib.h. |
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*/ |
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typedef ZSTD_inBuffer zstd_in_buffer; |
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/** |
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* struct zstd_out_buffer - output buffer for streaming |
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* @dst: Start of the output buffer. |
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* @size: Size of the output buffer. |
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* @pos: Position where writing stopped. Will be updated. |
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* Necessarily 0 <= pos <= size. |
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* |
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* See zstd_lib.h. |
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*/ |
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typedef ZSTD_outBuffer zstd_out_buffer; |
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/* ====== Streaming Compression ====== */ |
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typedef ZSTD_CStream zstd_cstream; |
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/** |
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* zstd_cstream_workspace_bound() - memory needed to initialize a zstd_cstream |
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* @cparams: The compression parameters to be used for compression. |
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* |
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* Return: A lower bound on the size of the workspace that is passed to |
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* zstd_init_cstream(). |
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*/ |
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size_t zstd_cstream_workspace_bound(const zstd_compression_parameters *cparams); |
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/** |
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* zstd_init_cstream() - initialize a zstd streaming compression context |
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* @parameters The zstd parameters to use for compression. |
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* @pledged_src_size: If params.fParams.contentSizeFlag == 1 then the caller |
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* must pass the source size (zero means empty source). |
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* Otherwise, the caller may optionally pass the source |
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* size, or zero if unknown. |
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* @workspace: The workspace to emplace the context into. It must outlive |
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* the returned context. |
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* @workspace_size: The size of workspace. |
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* Use zstd_cstream_workspace_bound(params->cparams) to |
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* determine how large the workspace must be. |
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* |
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* Return: The zstd streaming compression context or NULL on error. |
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*/ |
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zstd_cstream *zstd_init_cstream(const zstd_parameters *parameters, |
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unsigned long long pledged_src_size, void *workspace, size_t workspace_size); |
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/** |
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* zstd_reset_cstream() - reset the context using parameters from creation |
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* @cstream: The zstd streaming compression context to reset. |
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* @pledged_src_size: Optionally the source size, or zero if unknown. |
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* |
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* Resets the context using the parameters from creation. Skips dictionary |
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* loading, since it can be reused. If `pledged_src_size` is non-zero the frame |
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* content size is always written into the frame header. |
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* |
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* Return: Zero or an error, which can be checked using |
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* zstd_is_error(). |
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*/ |
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size_t zstd_reset_cstream(zstd_cstream *cstream, |
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unsigned long long pledged_src_size); |
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/** |
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* zstd_compress_stream() - streaming compress some of input into output |
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* @cstream: The zstd streaming compression context. |
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* @output: Destination buffer. `output->pos` is updated to indicate how much |
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* compressed data was written. |
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* @input: Source buffer. `input->pos` is updated to indicate how much data |
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* was read. Note that it may not consume the entire input, in which |
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* case `input->pos < input->size`, and it's up to the caller to |
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* present remaining data again. |
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* |
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* The `input` and `output` buffers may be any size. Guaranteed to make some |
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* forward progress if `input` and `output` are not empty. |
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* |
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* Return: A hint for the number of bytes to use as the input for the next |
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* function call or an error, which can be checked using |
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* zstd_is_error(). |
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*/ |
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size_t zstd_compress_stream(zstd_cstream *cstream, zstd_out_buffer *output, |
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zstd_in_buffer *input); |
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/** |
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* zstd_flush_stream() - flush internal buffers into output |
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* @cstream: The zstd streaming compression context. |
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* @output: Destination buffer. `output->pos` is updated to indicate how much |
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* compressed data was written. |
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* |
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* zstd_flush_stream() must be called until it returns 0, meaning all the data |
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* has been flushed. Since zstd_flush_stream() causes a block to be ended, |
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* calling it too often will degrade the compression ratio. |
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* |
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* Return: The number of bytes still present within internal buffers or an |
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* error, which can be checked using zstd_is_error(). |
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*/ |
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size_t zstd_flush_stream(zstd_cstream *cstream, zstd_out_buffer *output); |
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/** |
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* zstd_end_stream() - flush internal buffers into output and end the frame |
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* @cstream: The zstd streaming compression context. |
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* @output: Destination buffer. `output->pos` is updated to indicate how much |
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* compressed data was written. |
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* |
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* zstd_end_stream() must be called until it returns 0, meaning all the data has |
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* been flushed and the frame epilogue has been written. |
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* |
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* Return: The number of bytes still present within internal buffers or an |
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* error, which can be checked using zstd_is_error(). |
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*/ |
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size_t zstd_end_stream(zstd_cstream *cstream, zstd_out_buffer *output); |
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/* ====== Streaming Decompression ====== */ |
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typedef ZSTD_DStream zstd_dstream; |
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/** |
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* zstd_dstream_workspace_bound() - memory needed to initialize a zstd_dstream |
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* @max_window_size: The maximum window size allowed for compressed frames. |
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* |
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* Return: A lower bound on the size of the workspace that is passed |
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* to zstd_init_dstream(). |
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*/ |
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size_t zstd_dstream_workspace_bound(size_t max_window_size); |
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/** |
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* zstd_init_dstream() - initialize a zstd streaming decompression context |
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* @max_window_size: The maximum window size allowed for compressed frames. |
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* @workspace: The workspace to emplace the context into. It must outlive |
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* the returned context. |
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* @workspaceSize: The size of workspace. |
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* Use zstd_dstream_workspace_bound(max_window_size) to |
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* determine how large the workspace must be. |
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* |
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* Return: The zstd streaming decompression context. |
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*/ |
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zstd_dstream *zstd_init_dstream(size_t max_window_size, void *workspace, |
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size_t workspace_size); |
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/** |
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* zstd_reset_dstream() - reset the context using parameters from creation |
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* @dstream: The zstd streaming decompression context to reset. |
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* |
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* Resets the context using the parameters from creation. Skips dictionary |
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* loading, since it can be reused. |
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* |
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* Return: Zero or an error, which can be checked using zstd_is_error(). |
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*/ |
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size_t zstd_reset_dstream(zstd_dstream *dstream); |
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/** |
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* zstd_decompress_stream() - streaming decompress some of input into output |
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* @dstream: The zstd streaming decompression context. |
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* @output: Destination buffer. `output.pos` is updated to indicate how much |
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* decompressed data was written. |
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* @input: Source buffer. `input.pos` is updated to indicate how much data was |
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* read. Note that it may not consume the entire input, in which case |
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* `input.pos < input.size`, and it's up to the caller to present |
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* remaining data again. |
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* |
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* The `input` and `output` buffers may be any size. Guaranteed to make some |
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* forward progress if `input` and `output` are not empty. |
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* zstd_decompress_stream() will not consume the last byte of the frame until |
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* the entire frame is flushed. |
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* |
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* Return: Returns 0 iff a frame is completely decoded and fully flushed. |
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* Otherwise returns a hint for the number of bytes to use as the |
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* input for the next function call or an error, which can be checked |
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* using zstd_is_error(). The size hint will never load more than the |
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* frame. |
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*/ |
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size_t zstd_decompress_stream(zstd_dstream *dstream, zstd_out_buffer *output, |
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zstd_in_buffer *input); |
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/* ====== Frame Inspection Functions ====== */ |
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/** |
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* zstd_find_frame_compressed_size() - returns the size of a compressed frame |
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* @src: Source buffer. It should point to the start of a zstd encoded |
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* frame or a skippable frame. |
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* @src_size: The size of the source buffer. It must be at least as large as the |
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* size of the frame. |
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* |
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* Return: The compressed size of the frame pointed to by `src` or an error, |
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* which can be check with zstd_is_error(). |
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* Suitable to pass to ZSTD_decompress() or similar functions. |
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*/ |
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size_t zstd_find_frame_compressed_size(const void *src, size_t src_size); |
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/** |
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* struct zstd_frame_params - zstd frame parameters stored in the frame header |
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* @frameContentSize: The frame content size, or ZSTD_CONTENTSIZE_UNKNOWN if not |
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* present. |
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* @windowSize: The window size, or 0 if the frame is a skippable frame. |
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* @blockSizeMax: The maximum block size. |
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* @frameType: The frame type (zstd or skippable) |
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* @headerSize: The size of the frame header. |
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* @dictID: The dictionary id, or 0 if not present. |
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* @checksumFlag: Whether a checksum was used. |
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* |
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* See zstd_lib.h. |
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*/ |
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typedef ZSTD_frameHeader zstd_frame_header; |
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/** |
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* zstd_get_frame_header() - extracts parameters from a zstd or skippable frame |
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* @params: On success the frame parameters are written here. |
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* @src: The source buffer. It must point to a zstd or skippable frame. |
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* @src_size: The size of the source buffer. |
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* |
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* Return: 0 on success. If more data is required it returns how many bytes |
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* must be provided to make forward progress. Otherwise it returns |
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* an error, which can be checked using zstd_is_error(). |
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*/ |
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size_t zstd_get_frame_header(zstd_frame_header *params, const void *src, |
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size_t src_size); |
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#endif /* LINUX_ZSTD_H */
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