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/*
* Copyright (C) 2006, 2007 Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and/or 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 1.4 2007/06/19 23:47:17 tbox Exp $ */
#ifndef ISC_ATOMIC_H
#define ISC_ATOMIC_H 1
#include <isc/platform.h>
#include <isc/types.h>
#ifdef ISC_PLATFORM_USEGCCASM
/*
* This routine atomically increments the value stored in 'p' by 'val', and
* returns the previous value.
*
* Open issue: can 'fetchadd' make the code faster for some particular values
* (e.g., 1 and -1)?
*/
static inline isc_int32_t
isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
isc_int32_t prev, swapped;
for (prev = *(volatile isc_int32_t *)p; ; prev = swapped) {
swapped = prev + val;
__asm__ volatile(
"mov ar.ccv=%2;"
"cmpxchg4.acq %0=%4,%3,ar.ccv"
: "=r" (swapped), "=m" (*p)
: "r" (prev), "r" (swapped), "m" (*p)
: "memory");
if (swapped == prev)
break;
}
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(
"st4.rel %0=%1"
: "=m" (*p)
: "r" (val)
: "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) {
isc_int32_t ret;
__asm__ volatile(
"mov ar.ccv=%2;"
"cmpxchg4.acq %0=%4,%3,ar.ccv"
: "=r" (ret), "=m" (*p)
: "r" (cmpval), "r" (val), "m" (*p)
: "memory");
return (ret);
}
#else /* !ISC_PLATFORM_USEGCCASM */
#error "unsupported compiler. disable atomic ops by --disable-atomic"
#endif
#endif /* ISC_ATOMIC_H */
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