154 lines
4.6 KiB
C
154 lines
4.6 KiB
C
#ifndef LDM_H
|
|
#define LDM_H
|
|
|
|
#include <stddef.h> /* size_t */
|
|
|
|
#include "mem.h" // from /lib/common/mem.h
|
|
|
|
#define LDM_COMPRESS_SIZE 8
|
|
#define LDM_DECOMPRESS_SIZE 8
|
|
#define LDM_HEADER_SIZE ((LDM_COMPRESS_SIZE)+(LDM_DECOMPRESS_SIZE))
|
|
#define LDM_OFFSET_SIZE 4
|
|
|
|
// Defines the size of the hash table.
|
|
// Currently this should be less than WINDOW_SIZE_LOG + 4?
|
|
#define LDM_MEMORY_USAGE 23
|
|
|
|
//#define LDM_LAG (1 << 20)
|
|
#define LDM_LAG (0)
|
|
|
|
#define LDM_WINDOW_SIZE_LOG 28
|
|
#define LDM_WINDOW_SIZE (1 << (LDM_WINDOW_SIZE_LOG))
|
|
|
|
//These should be multiples of four (and perhaps set to the same values?).
|
|
#define LDM_MIN_MATCH_LENGTH 64
|
|
#define LDM_HASH_LENGTH 64
|
|
|
|
typedef struct LDM_compressStats LDM_compressStats;
|
|
typedef struct LDM_CCtx LDM_CCtx;
|
|
typedef struct LDM_DCtx LDM_DCtx;
|
|
|
|
/**
|
|
* 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 literals.
|
|
*
|
|
*/
|
|
size_t LDM_compress(const void *src, size_t srcSize,
|
|
void *dst, size_t maxDstSize);
|
|
|
|
/**
|
|
* Initialize the compression context.
|
|
*
|
|
* Allocates memory for the hash table.
|
|
*/
|
|
void LDM_initializeCCtx(LDM_CCtx *cctx,
|
|
const void *src, size_t srcSize,
|
|
void *dst, size_t maxDstSize);
|
|
|
|
/**
|
|
* Frees up memory allocating in initializeCCtx
|
|
*/
|
|
void LDM_destroyCCtx(LDM_CCtx *cctx);
|
|
|
|
/**
|
|
* Prints the distribution of offsets in the hash table.
|
|
*
|
|
* The offsets are defined as the distance of the hash table entry from the
|
|
* current input position of the cctx.
|
|
*/
|
|
void LDM_outputHashTableOffsetHistogram(const LDM_CCtx *cctx);
|
|
|
|
/**
|
|
* Outputs compression statistics to stdout.
|
|
*/
|
|
void LDM_printCompressStats(const LDM_compressStats *stats);
|
|
/**
|
|
* Checks whether the LDM_MIN_MATCH_LENGTH bytes from p are the same as the
|
|
* LDM_MIN_MATCH_LENGTH bytes from match and also if
|
|
* pIn - pMatch <= LDM_WINDOW_SIZE.
|
|
*
|
|
* This assumes LDM_MIN_MATCH_LENGTH is a multiple of four.
|
|
*
|
|
* Return 1 if valid, 0 otherwise.
|
|
*/
|
|
int LDM_isValidMatch(const BYTE *pIn, const BYTE *pMatch);
|
|
|
|
/**
|
|
* Counts the number of bytes that match from pIn and pMatch,
|
|
* up to pInLimit.
|
|
*/
|
|
U32 LDM_countMatchLength(const BYTE *pIn, const BYTE *pMatch,
|
|
const BYTE *pInLimit);
|
|
|
|
/**
|
|
* Encode the literal length followed by the literals.
|
|
*
|
|
* The literal length is written to the upper four bits of pToken, with
|
|
* additional bytes written to the output as needed (see lz4).
|
|
*
|
|
* This is followed by literalLength bytes corresponding to the literals.
|
|
*/
|
|
void LDM_encodeLiteralLengthAndLiterals(
|
|
LDM_CCtx *cctx, BYTE *pToken, const U32 literalLength);
|
|
|
|
/**
|
|
* Write current block (literals, literal length, match offset,
|
|
* match length).
|
|
*/
|
|
void LDM_outputBlock(LDM_CCtx *cctx,
|
|
const U32 literalLength,
|
|
const U32 offset,
|
|
const U32 matchLength);
|
|
|
|
/**
|
|
* Decompresses src into dst.
|
|
*
|
|
* Note: assumes src does not have a header.
|
|
*/
|
|
size_t LDM_decompress(const void *src, size_t srcSize,
|
|
void *dst, size_t maxDstSize);
|
|
|
|
/**
|
|
* Initialize the decompression context.
|
|
*/
|
|
void LDM_initializeDCtx(LDM_DCtx *dctx,
|
|
const void *src, size_t compressedSize,
|
|
void *dst, size_t maxDecompressedSize);
|
|
|
|
/**
|
|
* Reads the header from src and writes the compressed size and
|
|
* decompressed size into compressedSize and decompressedSize respectively.
|
|
*
|
|
* NB: LDM_compress and LDM_decompress currently do not add/read headers.
|
|
*/
|
|
void LDM_readHeader(const void *src, U64 *compressedSize,
|
|
U64 *decompressedSize);
|
|
|
|
void LDM_outputConfiguration(void);
|
|
|
|
void LDM_test(void);
|
|
|
|
#endif /* LDM_H */
|