dbc223eb84
Import existing source tree; original VCS history is no longer available. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
111 lines
3.1 KiB
C
111 lines
3.1 KiB
C
/*
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------------------------------------------------------------
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SFIFO 1.4
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------------------------------------------------------------
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* Simple portable lock-free FIFO
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* (c) 2000-2002, David Olofson
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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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* gcc / BeOS / x86: Works
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* gcc / BeOS / PPC: Works
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* ? / Solaris / x86 Works
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* ? / Solaris / SPARC Works
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* ? / AmigaOS / PPC Works
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* Borland C++ / Win32 / x86PM16: Untested
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* ? / Various Un*ces / ?: Untested
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* ? / Mac OS Classic / PPC: Untested
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* ? / ? / Alpha: Untested
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* ? / ? / MIPS: 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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* 1.4: Trying to make sfifo more robust, and easier to
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* use. It's now safe to close an sfifo more than
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* once. I've also changed some arguments and
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* variables to unsigned, to prevent signed input
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* from causing things to blow up. free/malloc
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* wrappers renamed _sf_free/_sf_malloc, to avoid
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* confusion and macro collisions.
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*
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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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/*------------------------------------------------
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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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unsigned 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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int sfifo_init(sfifo_t *f, unsigned size);
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void sfifo_close(sfifo_t *f);
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void sfifo_flush(sfifo_t *f);
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int sfifo_write(sfifo_t *f, const void *buf, unsigned len);
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int sfifo_read(sfifo_t *f, void *buf, unsigned 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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/*------------------------------------------------
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Linux kernel space interface
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------------------------------------------------*/
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#ifdef __KERNEL__
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int sfifo_write_user(sfifo_t *f, const void *buf, unsigned len);
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int sfifo_read_user(sfifo_t *f, void *buf, unsigned len);
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#else
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# define sfifo_write_user sfifo_write
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# define sfifo_read_user sfifo_read
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#endif
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#ifdef __cplusplus
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};
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#endif
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#endif
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