76 lines
2.6 KiB
C++
76 lines
2.6 KiB
C++
/* -*-c++-*-
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*
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* Copyright (C) 2005-2009 Mathias Froehlich
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include "SGAtomic.hxx"
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#if defined(SGATOMIC_USE_GCC4_BUILTINS) && defined (__i386__)
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// Usually the apropriate functions are inlined by gcc.
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// But if gcc is called with something aequivalent to -march=i386,
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// it will not assume that there is a lock instruction and instead
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// calls this pair of functions. We will provide them here in this case.
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// Note that this assembler code will not work on a i386 chip anymore.
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// But I hardly believe that we can assume to run at least on a i486 ...
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extern "C" {
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unsigned __sync_sub_and_fetch_4(volatile void *ptr, unsigned value)
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{
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register volatile unsigned* mem = reinterpret_cast<volatile unsigned*>(ptr);
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register unsigned result;
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__asm__ __volatile__("lock; xadd{l} {%0,%1|%1,%0}"
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: "=r" (result), "=m" (*mem)
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: "0" (-value), "m" (*mem)
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: "memory");
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return result - value;
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}
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unsigned __sync_add_and_fetch_4(volatile void *ptr, unsigned value)
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{
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register volatile unsigned* mem = reinterpret_cast<volatile unsigned*>(ptr);
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register unsigned result;
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__asm__ __volatile__("lock; xadd{l} {%0,%1|%1,%0}"
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: "=r" (result), "=m" (*mem)
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: "0" (value), "m" (*mem)
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: "memory");
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return result + value;
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}
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unsigned __sync_bool_compare_and_swap_4(volatile void *ptr,
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unsigned oldValue, unsigned newValue)
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{
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register volatile unsigned* mem = reinterpret_cast<volatile unsigned*>(ptr);
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unsigned before;
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__asm__ __volatile__("lock; cmpxchg{l} {%1,%2|%1,%2}"
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: "=a"(before)
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: "q"(newValue), "m"(*mem), "0"(oldValue)
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: "memory");
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return before == oldValue;
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}
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void __sync_synchronize()
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{
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__asm__ __volatile__("": : : "memory");
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}
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} // extern "C"
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#endif
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