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Implement atomic_swap_<type>.

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The operation was documented and implemented partially (both from a
type and architecture perspective) on 2013-08-21 and got used in
ZFS with revision 260150 (zfeature.c) and since ZFS is supported on
ia64, the lack of having atomic_swap became problem.
This commit is contained in:
Marcel Moolenaar 2014-01-01 22:51:19 +00:00
parent 7ee35ac9f3
commit 37ed8bfa35
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=260175
1 changed files with 28 additions and 0 deletions
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28
sys/ia64/include/atomic.h
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@ -386,4 +386,32 @@ atomic_fetchadd_long(volatile u_long *p, u_long v)
return (value);
}
/*
* <type> atomic_swap_<type>(volatile <type> *p, <type> v);
*/
static __inline uint32_t
atomic_swap_32(volatile uint32_t *p, uint32_t v)
{
uint32_t r;
__asm __volatile ("xchg4 %0 = %3, %2;;" : "=r"(r), "=m"(*p) :
"r"(v), "m"(*p) : "memory");
return (r);
}
static __inline uint64_t
atomic_swap_64(volatile uint64_t *p, uint64_t v)
{
uint64_t r;
__asm __volatile ("xchg8 %0 = %3, %2;;" : "=r"(r), "=m"(*p) :
"r"(v), "m"(*p) : "memory");
return (r);
}
#define atomic_swap_int atomic_swap_32
#define atomic_swap_long atomic_swap_64
#define atomic_swap_ptr atomic_swap_64
#endif /* ! _MACHINE_ATOMIC_H_ */