atomic.h revision 5597be9bb88de138dfec9fa9176708443813925e
/*
* Copyright (C) 2005 Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id: atomic.h,v 1.2 2005/06/04 05:32:50 jinmei Exp $ */
#ifndef ISC_ATOMIC_H
#define ISC_ATOMIC_H 1
#include <isc/platform.h>
#include <isc/types.h>
/*
* This routine atomically increments the value stored in 'p' by 'val', and
* returns the previous value.
*/
static inline isc_int32_t
isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
isc_int32_t prev = val;
__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
"lock;"
#endif
"xadd %0, %1"
:"=q"(prev)
:"m"(*p), "0"(prev)
:"memory", "cc");
return (prev);
}
/*
* This routine atomically stores the value 'val' in 'p'.
*/
static inline void
isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
/*
* xchg should automatically lock memory, but we add it
* explicitly just in case (it at least doesn't harm)
*/
"lock;"
#endif
"xchgl %1, %0"
:
: "r"(val), "m"(*p)
: "memory");
}
/*
* This routine atomically replaces the value in 'p' with 'val', if the
* original value is equal to 'cmpval'. The original value is returned in any
* case.
*/
static inline isc_int32_t
isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
"lock;"
#endif
"cmpxchgl %1, %2"
: "=a"(cmpval)
: "r"(val), "m"(*p), "a"(cmpval)
: "memory");
return (cmpval);
}
#endif /* ISC_ATOMIC_H */