fastlz.h File Reference

#include <inttypes.h>

Go to the source code of this file.

Defines
#define	flzuint8   uint8_t
#define	flzuint16   uint16_t
#define	flzuint32   uint32_t
#define	FASTLZ_VERSION   0x000100
#define	FASTLZ_VERSION_MAJOR   0
#define	FASTLZ_VERSION_MINOR   0
#define	FASTLZ_VERSION_REVISION   0
#define	FASTLZ_VERSION_STRING   "0.1.0"
Functions
int	fastlz_compress (const void *input, int length, void *output)
int	fastlz_decompress (const void *input, int length, void *output, int maxout)
int	fastlz_compress_level (int level, const void *input, int length, void *output)

---

Define Documentation

#define FASTLZ_VERSION   0x000100

#define FASTLZ_VERSION_MAJOR   0

#define FASTLZ_VERSION_MINOR   0

#define FASTLZ_VERSION_REVISION   0

#define FASTLZ_VERSION_STRING   "0.1.0"

#define flzuint16   uint16_t

#define flzuint32   uint32_t

#define flzuint8   uint8_t

Referenced by fastlz_decompress().

---

Function Documentation

int fastlz_compress	(	const void *	input,
		int	length,
		void *	output
	)

Compress a block of data in the input buffer and returns the size of compressed block. The size of input buffer is specified by length. The minimum input buffer size is 16.

The output buffer must be at least 5% larger than the input buffer and can not be smaller than 66 bytes.

If the input is not compressible, the return value might be larger than length (input buffer size).

The input buffer and the output buffer can not overlap.

Referenced by fstWriterFlushContext().

{
  /* for short block, choose fastlz1 */
  if(length < 65536)
    return fastlz1_compress(input, length, output);

  /* else... */
  return fastlz2_compress(input, length, output);
}

int fastlz_compress_level	(	int	level,
		const void *	input,
		int	length,
		void *	output
	)

Compress a block of data in the input buffer and returns the size of compressed block. The size of input buffer is specified by length. The minimum input buffer size is 16.

The output buffer must be at least 5% larger than the input buffer and can not be smaller than 66 bytes.

If the input is not compressible, the return value might be larger than length (input buffer size).

The input buffer and the output buffer can not overlap.

Compression level can be specified in parameter level. At the moment, only level 1 and level 2 are supported. Level 1 is the fastest compression and generally useful for short data. Level 2 is slightly slower but it gives better compression ratio.

Note that the compressed data, regardless of the level, can always be decompressed using the function fastlz_decompress above.

{
  if(level == 1)
    return fastlz1_compress(input, length, output);
  if(level == 2)
    return fastlz2_compress(input, length, output);

  return 0;
}

int fastlz_decompress	(	const void *	input,
		int	length,
		void *	output,
		int	maxout
	)

Decompress a block of compressed data and returns the size of the decompressed block. If error occurs, e.g. the compressed data is corrupted or the output buffer is not large enough, then 0 (zero) will be returned instead.

The input buffer and the output buffer can not overlap.

Decompression is memory safe and guaranteed not to write the output buffer more than what is specified in maxout.

References flzuint8.

Referenced by fstReaderIterBlocks().

{
  /* magic identifier for compression level */
  int level = ((*(const flzuint8*)input) >> 5) + 1;

  if(level == 1)
    return fastlz1_decompress(input, length, output, maxout);
  if(level == 2)
    return fastlz2_decompress(input, length, output, maxout);

  /* unknown level, trigger error */
  return 0;
}