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/* Copyright (C) 2006 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
XXX 64-bit atomic operations can be implemented using
cmpxchg8b, if necessary. Though I've heard that not all 64-bit
architectures support double-word (128-bit) cas.
*/
#ifdef MY_ATOMIC_NO_XADD
#define MY_ATOMIC_MODE "gcc-x86" LOCK "-no-xadd"
#else
#define MY_ATOMIC_MODE "gcc-x86" LOCK
#endif
/* fix -ansi errors while maintaining readability */
#ifndef asm
#define asm __asm__
#endif
#ifndef MY_ATOMIC_NO_XADD
#define make_atomic_add_body(S) \
asm volatile (LOCK "; xadd %0, %1;" : "+r" (v) , "+m" (*a))
#endif
#define make_atomic_swap_body(S) \
asm volatile ("; xchg %0, %1;" : "+r" (v) , "+m" (*a))
#define make_atomic_cas_body(S) \
asm volatile (LOCK "; cmpxchg %3, %0; setz %2;" \
: "+m" (*a), "+a" (*cmp), "=q" (ret): "r" (set))
#ifdef MY_ATOMIC_MODE_DUMMY
#define make_atomic_load_body(S) ret=*a
#define make_atomic_store_body(S) *a=v
#else
/*
Actually 32-bit reads/writes are always atomic on x86
But we add LOCK here anyway to force memory barriers
*/
#define make_atomic_load_body(S) \
ret=0; \
asm volatile (LOCK "; cmpxchg %2, %0" \
: "+m" (*a), "+a" (ret): "r" (ret))
#define make_atomic_store_body(S) \
asm volatile ("; xchg %0, %1;" : "+m" (*a) : "r" (v))
#endif
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