/*

	SFIFO 1.3 Simple portable lock-free FIFO

	(c) 2000-2002, David Olofson - free software under the terms of the LGPL 2.1

*/

/*

 * Platform support:

 *	gcc / Linux / x86:		Works

 *	gcc / Linux / x86 kernel:	Works

 *	gcc / FreeBSD / x86:		Works

 *	gcc / NetBSD / x86:		Works

 *	gcc / Mac OS X / PPC:		Works

 *	gcc / Win32 / x86:		Works

 *	Borland C++ / DOS / x86RM:	Works

 *	Borland C++ / Win32 / x86PM16:	Untested

 *	? / Various Un*ces / ?:		Untested

 *	? / Mac OS / PPC:		Untested

 *	gcc / BeOS / x86:		Untested

 *	gcc / BeOS / PPC:		Untested

 *	? / ? / Alpha:			Untested

 *

 * 1.2: Max buffer size halved, to avoid problems with

 *	the sign bit...

 *

 * 1.3:	Critical buffer allocation bug fixed! For certain

 *	requested buffer sizes, older version would

 *	allocate a buffer of insufficient size, which

 *	would result in memory thrashing. (Amazing that

 *	I've manage to use this to the extent I have

 *	without running into this... *heh*)

 */

#ifndef	_SFIFO_H_

#define	_SFIFO_H_

#ifdef __cplusplus

extern "C" {

#endif

#include <errno.h>

/* Defining SFIFO_STATIC and then including the sfifo.c will result in local code. */

#ifdef SFIFO_STATIC

#define SFIFO_SCOPE static

#else

#define SFIFO_SCOPE

#endif

/*------------------------------------------------

	"Private" stuff

------------------------------------------------*/

/*

 * Porting note:

 *	Reads and writes of a variable of this type in memory

 *	must be *atomic*! 'int' is *not* atomic on all platforms.

 *	A safe type should be used, and  sfifo should limit the

 *	maximum buffer size accordingly.

 */

typedef int sfifo_atomic_t;

#ifdef __TURBOC__

#	define	SFIFO_MAX_BUFFER_SIZE	0x7fff

#else /* Kludge: Assume 32 bit platform */

#	define	SFIFO_MAX_BUFFER_SIZE	0x7fffffff

#endif

typedef struct sfifo_t

{

	char *buffer;

	int size;			/* Number of bytes */

	sfifo_atomic_t readpos;		/* Read position */

	sfifo_atomic_t writepos;	/* Write position */

} sfifo_t;

#define SFIFO_SIZEMASK(x)	((x)->size - 1)

/*------------------------------------------------

	API

------------------------------------------------*/

SFIFO_SCOPE int sfifo_init(sfifo_t *f, int size);

SFIFO_SCOPE void sfifo_close(sfifo_t *f);

SFIFO_SCOPE void sfifo_flush(sfifo_t *f);

SFIFO_SCOPE int sfifo_write(sfifo_t *f, const void *buf, int len);

SFIFO_SCOPE int sfifo_read(sfifo_t *f, void *buf, int len);

#define sfifo_used(x)	(((x)->writepos - (x)->readpos) & SFIFO_SIZEMASK(x))

#define sfifo_space(x)	((x)->size - 1 - sfifo_used(x))

#define sfifo_size(x)	((x)->size - 1)

#ifdef __cplusplus

};

#endif

#endif