simgear/structure/SGAtomic.cxx

   1 /* -*-c++-*-
   2  *
   3  * Copyright (C) 2005-2009,2011 Mathias Froehlich
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation; either version 2 of the
   8  * License, or (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  18  *
  19  */
  20
  21 #ifdef HAVE_CONFIG_H
  22 #  include <simgear_config.h>
  23 #endif
  24
  25 #include "SGAtomic.hxx"
  26
  27 #if defined(SGATOMIC_USE_LIBRARY_FUNCTIONS)
  28
  29 #if defined(_WIN32)
  30 # include <windows.h>
  31 #elif defined(GCC_ATOMIC_BUILTINS_FOUND)
  32 #elif defined(__GNUC__) && defined(__i386__)
  33 #elif defined(SGATOMIC_USE_MUTEX)
  34 # include <simgear/threads/SGGuard.hxx>
  35 #else
  36 # error
  37 #endif
  38
  39 unsigned
  40 SGAtomic::operator++()
  41 {
  42 #if defined(_WIN32)
  43     return InterlockedIncrement(reinterpret_cast<long volatile*>(&mValue));
  44 #elif defined(GCC_ATOMIC_BUILTINS_FOUND)
  45     return __sync_add_and_fetch(&mValue, 1);
  46 #elif defined(__GNUC__) && defined(__i386__)
  47     register volatile unsigned* mem = reinterpret_cast<volatile unsigned*>(&mValue);
  48     register unsigned result;
  49     __asm__ __volatile__("lock; xadd{l} {%0,%1|%1,%0}"
  50                          : "=r" (result), "=m" (*mem)
  51                          : "0" (1), "m" (*mem)
  52                          : "memory");
  53     return result + 1;
  54 #else
  55     SGGuard<SGMutex> lock(mMutex);
  56     return ++mValue;
  57 #endif
  58 }
  59
  60 unsigned
  61 SGAtomic::operator--()
  62 {
  63 #if defined(_WIN32)
  64     return InterlockedDecrement(reinterpret_cast<long volatile*>(&mValue));
  65 #elif defined(GCC_ATOMIC_BUILTINS_FOUND)
  66     return __sync_sub_and_fetch(&mValue, 1);
  67 #elif defined(__GNUC__) && defined(__i386__)
  68     register volatile unsigned* mem = reinterpret_cast<volatile unsigned*>(&mValue);
  69     register unsigned result;
  70     __asm__ __volatile__("lock; xadd{l} {%0,%1|%1,%0}"
  71                          : "=r" (result), "=m" (*mem)
  72                          : "0" (-1), "m" (*mem)
  73                          : "memory");
  74     return result - 1;
  75 #else
  76     SGGuard<SGMutex> lock(mMutex);
  77     return --mValue;
  78 #endif
  79 }
  80
  81 SGAtomic::operator unsigned() const
  82 {
  83 #if defined(_WIN32)
  84     return static_cast<unsigned const volatile &>(mValue);
  85 #elif defined(GCC_ATOMIC_BUILTINS_FOUND)
  86     __sync_synchronize();
  87     return mValue;
  88 #elif defined(__GNUC__) && defined(__i386__)
  89     __asm__ __volatile__("": : : "memory");
  90     return mValue;
  91 #else
  92     SGGuard<SGMutex> lock(mMutex);
  93     return mValue;
  94 #endif
  95 }
  96
  97 bool
  98 SGAtomic::compareAndExchange(unsigned oldValue, unsigned newValue)
  99 {
 100 #if defined(_WIN32)
 101     long volatile* lvPtr = reinterpret_cast<long volatile*>(&mValue);
 102     return oldValue == InterlockedCompareExchange(lvPtr, newValue, oldValue);
 103 #elif defined(GCC_ATOMIC_BUILTINS_FOUND)
 104     return __sync_bool_compare_and_swap(&mValue, oldValue, newValue);
 105 #elif defined(__GNUC__) && defined(__i386__)
 106     register volatile unsigned* mem = reinterpret_cast<volatile unsigned*>(&mValue);
 107     unsigned before;
 108     __asm__ __volatile__("lock; cmpxchg{l} {%1,%2|%1,%2}"
 109                          : "=a"(before)
 110                          : "q"(newValue), "m"(*mem), "0"(oldValue)
 111                          : "memory");
 112     return before == oldValue;
 113 #else
 114     SGGuard<SGMutex> lock(mMutex);
 115     if (mValue != oldValue)
 116         return false;
 117     mValue = newValue;
 118     return true;
 119 #endif
 120 }
 121
 122 #endif