95 lines
2.5 KiB
C
95 lines
2.5 KiB
C
/*
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SFIFO 1.3 Simple portable lock-free FIFO
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(c) 2000-2002, David Olofson - free software under the terms of the LGPL 2.1
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*/
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/*
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* Platform support:
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* gcc / Linux / x86: Works
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* gcc / Linux / x86 kernel: Works
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* gcc / FreeBSD / x86: Works
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* gcc / NetBSD / x86: Works
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* gcc / Mac OS X / PPC: Works
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* gcc / Win32 / x86: Works
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* Borland C++ / DOS / x86RM: Works
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* Borland C++ / Win32 / x86PM16: Untested
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* ? / Various Un*ces / ?: Untested
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* ? / Mac OS / PPC: Untested
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* gcc / BeOS / x86: Untested
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* gcc / BeOS / PPC: Untested
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* ? / ? / Alpha: Untested
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*
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* 1.2: Max buffer size halved, to avoid problems with
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* the sign bit...
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*
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* 1.3: Critical buffer allocation bug fixed! For certain
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* requested buffer sizes, older version would
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* allocate a buffer of insufficient size, which
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* would result in memory thrashing. (Amazing that
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* I've manage to use this to the extent I have
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* without running into this... *heh*)
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*/
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#ifndef _SFIFO_H_
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#define _SFIFO_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <errno.h>
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/* Defining SFIFO_STATIC and then including the sfifo.c will result in local code. */
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#ifdef SFIFO_STATIC
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#define SFIFO_SCOPE static
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#else
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#define SFIFO_SCOPE
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#endif
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/*------------------------------------------------
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"Private" stuff
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------------------------------------------------*/
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/*
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* Porting note:
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* Reads and writes of a variable of this type in memory
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* must be *atomic*! 'int' is *not* atomic on all platforms.
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* A safe type should be used, and sfifo should limit the
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* maximum buffer size accordingly.
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*/
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typedef int sfifo_atomic_t;
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#ifdef __TURBOC__
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# define SFIFO_MAX_BUFFER_SIZE 0x7fff
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#else /* Kludge: Assume 32 bit platform */
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# define SFIFO_MAX_BUFFER_SIZE 0x7fffffff
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#endif
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typedef struct sfifo_t
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{
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char *buffer;
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int size; /* Number of bytes */
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sfifo_atomic_t readpos; /* Read position */
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sfifo_atomic_t writepos; /* Write position */
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} sfifo_t;
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#define SFIFO_SIZEMASK(x) ((x)->size - 1)
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/*------------------------------------------------
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API
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------------------------------------------------*/
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SFIFO_SCOPE int sfifo_init(sfifo_t *f, int size);
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SFIFO_SCOPE void sfifo_close(sfifo_t *f);
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SFIFO_SCOPE void sfifo_flush(sfifo_t *f);
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SFIFO_SCOPE int sfifo_write(sfifo_t *f, const void *buf, int len);
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SFIFO_SCOPE int sfifo_read(sfifo_t *f, void *buf, int len);
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#define sfifo_used(x) (((x)->writepos - (x)->readpos) & SFIFO_SIZEMASK(x))
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#define sfifo_space(x) ((x)->size - 1 - sfifo_used(x))
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#define sfifo_size(x) ((x)->size - 1)
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#ifdef __cplusplus
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};
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#endif
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#endif
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