zstd/contrib/long_distance_matching/ldm.h

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#ifndef LDM_H
#define LDM_H
#include <stddef.h> /* size_t */
#define LDM_COMPRESS_SIZE 8
#define LDM_DECOMPRESS_SIZE 8
#define LDM_HEADER_SIZE ((LDM_COMPRESS_SIZE)+(LDM_DECOMPRESS_SIZE))
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/**
* Compresses src into dst.
*
* NB: This currently ignores maxDstSize and assumes enough space is available.
*
* Block format (see lz4 documentation for more information):
* github.com/lz4/lz4/blob/dev/doc/lz4_Block_format.md
*
* A block is composed of sequences. Each sequence begins with a token, which
* is a one-byte value separated into two 4-bit fields.
*
* The first field uses the four high bits of the token and encodes the literal
* length. If the field value is 0, there is no literal. If it is 15,
* additional bytes are added (each ranging from 0 to 255) to the previous
* value to produce a total length.
*
* Following the token and optional length bytes are the literals.
*
* Next are the 4 bytes representing the offset of the match (2 in lz4),
* representing the position to copy the literals.
*
* The lower four bits of the token encode the match length. With additional
* bytes added similarly to the additional literal length bytes after the offset.
*
* The last sequence is incomplete and stops right after the lieterals.
*
*/
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size_t LDM_compress(const void *src, size_t srcSize,
void *dst, size_t maxDstSize);
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size_t LDM_decompress(const void *src, size_t srcSize,
void *dst, size_t maxDstSize);
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/**
* Reads the header from src and writes the compressed size and
* decompressed size into compressSize and decompressSize respectively.
*
* NB: LDM_compress and LDM_decompress currently do not add/read headers.
*/
void LDM_readHeader(const void *src, size_t *compressSize,
size_t *decompressSize);
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void LDM_test(const void *src, size_t srcSize,
void *dst, size_t maxDstSize);
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#endif /* LDM_H */