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