| // Low-level functions for atomic operations: x86, x >= 3 version -*- C++ -*- |
| |
| // Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library 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; either version 2, or (at your option) |
| // any later version. |
| |
| // This library 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 library; see the file COPYING. If not, write to the Free |
| // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| // USA. |
| |
| // As a special exception, you may use this file as part of a free software |
| // library without restriction. Specifically, if other files instantiate |
| // templates or use macros or inline functions from this file, or you compile |
| // this file and link it with other files to produce an executable, this |
| // file does not by itself cause the resulting executable to be covered by |
| // the GNU General Public License. This exception does not however |
| // invalidate any other reasons why the executable file might be covered by |
| // the GNU General Public License. |
| |
| #include <ext/atomicity.h> |
| |
| _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) |
| |
| template<int __inst> |
| struct _Atomicity_lock |
| { |
| static volatile _Atomic_word _S_atomicity_lock; |
| }; |
| |
| template<int __inst> |
| volatile _Atomic_word _Atomicity_lock<__inst>::_S_atomicity_lock = 0; |
| |
| template volatile _Atomic_word _Atomicity_lock<0>::_S_atomicity_lock; |
| |
| _Atomic_word |
| __attribute__ ((__unused__)) |
| __exchange_and_add(volatile _Atomic_word* __mem, int __val) |
| { |
| register _Atomic_word __result, __tmp = 1; |
| |
| // Obtain the atomic exchange/add spin lock. |
| do |
| { |
| __asm__ __volatile__ ("xchg{l} {%0,%1|%1,%0}" |
| : "=m" (_Atomicity_lock<0>::_S_atomicity_lock), |
| "+r" (__tmp) |
| : "m" (_Atomicity_lock<0>::_S_atomicity_lock)); |
| } |
| while (__tmp); |
| |
| __result = *__mem; |
| *__mem += __val; |
| |
| // Release spin lock. |
| _Atomicity_lock<0>::_S_atomicity_lock = 0; |
| |
| return __result; |
| } |
| |
| void |
| __attribute__ ((__unused__)) |
| __atomic_add(volatile _Atomic_word* __mem, int __val) |
| { __exchange_and_add(__mem, __val); } |
| |
| _GLIBCXX_END_NAMESPACE |
