windows-nt/Source/XPSP1/NT/base/ntos/inc/xpress.h

#ifndef _XPRESS_H_
#define _XPRESS_H_

#ifdef _MSC_VER
#pragma once
#endif


/* -------------------------------------------------------------------- */
/*                                                                      */
/*               Copyright (c) 1991-1999 by Andrew Kadatch              */
/*                                                                      */
/* -------------------------------------------------------------------- */

#ifdef __cplusplus
extern "C" {
#endif

/* ---------------------- Common declarations ------------------------- */
/*                        -------------------                           */

// max. size of input block
#define XPRESS_MAX_BLOCK_LOG	16
#define XPRESS_MAX_BLOCK	(1 << XPRESS_MAX_BLOCK_LOG)


// preferred data alignment to avoid misaligned accesses
#define XPRESS_ALIGNMENT	8

// declare default calling convention used in xpress
#if !defined (UNIX) && !defined (XPRESS_CALL)
#define XPRESS_CALL __stdcall
#endif


// user-supplied callback function that allocates memory
// if there is no memory available it shall return NULL
typedef
void *
XPRESS_CALL
  XpressAllocFn
  (
    void *context,	// user-defined context (as passed to XpressEncodeCreate)
    int size		// size of memory block to allocate
  );

// user-supplied callback function that releases memory
typedef
void
XPRESS_CALL
  XpressFreeFn
  (
    void *context,	// user-defined context (as passed to XpressEncodeClose)
    void *address	// pointer to the block to be freed
  );


/* ----------------------------- Encoder ------------------------------ */
/*                               -------                                */

// declare unique anonymous types for type safety
typedef struct {int XpressEncodeDummy;} *XpressEncodeStream;

// allocate and initialize encoder's data structures
// returns NULL if callback returned NULL (not enough memory)
XpressEncodeStream
XPRESS_CALL
  XpressEncodeCreate
  (
    int MaxOrigSize,			// max size of original data block
    void *context,			// user-defined context info (will  be passed to AllocFn)
    XpressAllocFn *AllocFn,		// memory allocation callback
    int CompressionLevel		// use 0 for speed, 9 for quality
  );


// callback function called by XpressEncode to indicate compression progress
typedef
void
XPRESS_CALL
  XpressProgressFn
  (
    void *context,			// user-defined context
    int compressed			// size of processed original data
  );
    

// returns size of compressed data
// if compression failed then compressed buffer is left as is, and
// original data should be saved instead
int
XPRESS_CALL
  XpressEncode
  (
    XpressEncodeStream stream,		// encoder's workspace
    void *CompAdr, int CompSize,	// compressed data region
    const void *OrigAdr, int OrigSize,	// input data block
    XpressProgressFn *ProgressFn,	// NULL or progress callback
    void *ProgressContext,		// user-defined context that will be passed to ProgressFn
    int ProgressSize			// call ProgressFn each time ProgressSize bytes processed
  );

// invalidate input stream and release workspace memory
void
XPRESS_CALL
  XpressEncodeClose
  (
    XpressEncodeStream stream,		// encoder's workspace
    void *context, XpressFreeFn *FreeFn	// memory releasing callback
  );


/* ----------------------------- Decoder ------------------------------ */
/*                               -------                                */

// declare unique anonymous types for type safety
typedef struct {int XpressDecodeDummy;} *XpressDecodeStream;

// allocate memory for decoder. Returns NULL if not enough memory.
XpressDecodeStream
XPRESS_CALL
  XpressDecodeCreate
  (
    void *context,			// user-defined context info (will  be passed to AllocFn)
    XpressAllocFn *AllocFn		// memory allocation callback
  );

// decode compressed block. Returns # of decoded bytes or -1 otherwise
int
XPRESS_CALL
XpressDecode
  (
    XpressDecodeStream stream,		// decoder's workspace
    void *OrigAdr, int OrigSize,	// original data region
    int DecodeSize,			// # of bytes to decode ( <= OrigSize)
    const void *CompAdr, int CompSize	// compressed data block
  );

void
XPRESS_CALL
  XpressDecodeClose
  (
    XpressDecodeStream stream,		// encoder's workspace
    void *context,			// user-defined context info (will  be passed to FreeFn)
    XpressFreeFn *FreeFn			// callback that releases the memory
  );


/* ------------------------------ CRC32 ------------------------------- */
/*                                -----                                 */

int
XPRESS_CALL
  XpressCrc32
  (
    const void *data,		// beginning of data block
    int bytes,			// number of bytes
    int crc			// initial value
  );


#ifdef __cplusplus
};
#endif

#endif /* _XPRESS_H_ */