libstdc++-v3/config/cpu/m68k/atomicity.h

   1 // Low-level functions for atomic operations: m68k version -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #include <ext/atomicity.h>
  26
  27 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  28
  29 #if ( defined(__mc68020__) || defined(__mc68030__) \
  30       || defined(__mc68040__) || defined(__mc68060__) ) \
  31     && !defined(__mcpu32__)
  32   // These variants support compare-and-swap.
  33   _Atomic_word
  34   __attribute__ ((__unused__))
  35   __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
  36   {
  37     register _Atomic_word __result = *__mem;
  38     register _Atomic_word __temp;
  39     __asm__ __volatile__ ("1: move%.l %0,%1\n\t"
  40                           "add%.l %3,%1\n\t"
  41                           "cas%.l %0,%1,%2\n\t"
  42                           "jne 1b"
  43                           : "=d" (__result), "=&d" (__temp), "=m" (*__mem)
  44                           : "d" (__val), "0" (__result), "m" (*__mem));
  45     return __result;
  46   }
  47
  48 #elif defined(__rtems__)
  49   // TAS/JBNE is unsafe on systems with strict priority-based scheduling.
  50   // Disable interrupts, which we can do only from supervisor mode.
  51   _Atomic_word
  52   __attribute__ ((__unused__))
  53   __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
  54   {
  55     _Atomic_word __result;
  56     short __level, __tmpsr;
  57     __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr"
  58                           : "=d"(__level), "=d"(__tmpsr) : "1"(0x700));
  59
  60     __result = *__mem;
  61     *__mem = __result + __val;
  62     __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));
  63
  64     return __result;
  65   }
  66
  67 #else
  68
  69   template<int __inst>
  70     struct _Atomicity_lock
  71     {
  72       static volatile unsigned char _S_atomicity_lock;
  73     };
  74
  75   template<int __inst>
  76   volatile unsigned char _Atomicity_lock<__inst>::_S_atomicity_lock = 0;
  77
  78   template volatile unsigned char _Atomicity_lock<0>::_S_atomicity_lock;
  79
  80   _Atomic_word
  81   __attribute__ ((__unused__))
  82   __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
  83   {
  84     _Atomic_word __result;
  85
  86     // bset with no immediate addressing (not SMP-safe)
  87 #if defined(__mcfisaa__) || defined(__mcfisaaplus__)
  88     __asm__ __volatile__("1: bset.b #7,%0@\n\tjbne 1b"
  89                          : /* no outputs */
  90                          : "a"(&_Atomicity_lock<0>::_S_atomicity_lock)
  91                          : "cc", "memory");
  92
  93     // CPU32 and CF ISAs B & C support test-and-set (SMP-safe).
  94 #elif defined(__mcpu32__) || defined(__mcfisab__) || defined (__mcfisac__)
  95     __asm__ __volatile__("1: tas %0\n\tjbne 1b"
  96                          : "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
  97                          : /* none */
  98                          : "cc");
  99
 100     // Use bset with immediate addressing for 68000/68010 (not SMP-safe)
 101     // NOTE: TAS is available on the 68000, but unsupported by some Amiga
 102     // memory controllers.
 103 #else
 104     __asm__ __volatile__("1: bset.b #7,%0\n\tjbne 1b"
 105                          : "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
 106                          : /* none */
 107                          : "cc");
 108 #endif
 109
 110     __result = *__mem;
 111     *__mem = __result + __val;
 112
 113     _Atomicity_lock<0>::_S_atomicity_lock = 0;
 114
 115     return __result;
 116   }
 117
 118 #endif /* TAS / BSET */
 119
 120   void
 121   __attribute__ ((__unused__))
 122   __atomic_add(volatile _Atomic_word* __mem, int __val) throw ()
 123   {
 124     // Careful: using add.l with a memory destination is not
 125     // architecturally guaranteed to be atomic.
 126     __exchange_and_add(__mem, __val);
 127   }
 128
 129 _GLIBCXX_END_NAMESPACE