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

   1 // Low-level functions for atomic operations: m68k version -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 #ifndef _GLIBCXX_ATOMICITY_H
  31 #define _GLIBCXX_ATOMICITY_H    1
  32
  33 typedef int _Atomic_word;
  34
  35 #if ( defined(__mc68020__) || defined(__mc68030__) \
  36       || defined(__mc68040__) || defined(__mc68060__) ) \
  37     && !defined(__mcpu32__)
  38 // These variants support compare-and-swap.
  39
  40 static inline _Atomic_word
  41 __attribute__ ((__unused__))
  42 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
  43 {
  44   register _Atomic_word __result = *__mem;
  45   register _Atomic_word __temp;
  46   __asm__ __volatile__ ("1: move%.l %0,%1\n\t"
  47                         "add%.l %3,%1\n\t"
  48                         "cas%.l %0,%1,%2\n\t"
  49                         "jne 1b"
  50                         : "=d" (__result), "=&d" (__temp), "+m" (*__mem)
  51                         : "d" (__val), "0" (__result)
  52                         : "memory");
  53   return __result;
  54 }
  55
  56 #elif defined(__rtems__)
  57   /*
  58    * TAS/JBNE is unsafe on systems with strict priority-based scheduling.
  59    * Disable interrupts, which we can do only from supervisor mode.
  60    */
  61 static inline _Atomic_word
  62 __attribute__ ((__unused__))
  63 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
  64 {
  65   _Atomic_word __result;
  66   short __level, __tmpsr;
  67   __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr"
  68                        : "=d"(__level), "=d"(__tmpsr) : "1"(0x700));
  69
  70   __result = *__mem;
  71   *__mem = __result + __val;
  72
  73   __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));
  74
  75   return __result;
  76 }
  77
  78 #else
  79
  80 template<int __inst>
  81   struct __Atomicity_lock
  82   {
  83     static volatile unsigned char _S_atomicity_lock;
  84   };
  85
  86 template<int __inst>
  87 volatile unsigned char __Atomicity_lock<__inst>::_S_atomicity_lock = 0;
  88
  89 template volatile unsigned char __Atomicity_lock<0>::_S_atomicity_lock;
  90
  91 static inline _Atomic_word
  92 __attribute__ ((__unused__))
  93 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
  94 {
  95   _Atomic_word __result;
  96
  97 // bset with no immediate addressing (not SMP-safe)
  98 #if defined(__mcf5200__) || defined(__mcf5300__)
  99   __asm__ __volatile__("1: bset.b #7,%0@\n\tjbne 1b"
 100                        : /* no outputs */
 101                        : "a"(&__Atomicity_lock<0>::_S_atomicity_lock)
 102                        : "cc", "memory");
 103
 104 // CPU32 and MCF5400 support test-and-set (SMP-safe).
 105 #elif defined(__mcpu32__) || defined(__mcf5400__)
 106   __asm__ __volatile__("1: tas %0\n\tjbne 1b"
 107                        : "+m"(__Atomicity_lock<0>::_S_atomicity_lock)
 108                        : /* none */
 109                        : "cc");
 110
 111 // Use bset with immediate addressing for 68000/68010 (not SMP-safe)
 112 // NOTE: TAS is available on the 68000, but unsupported by some Amiga
 113 // memory controllers.
 114 #else
 115   __asm__ __volatile__("1: bset.b #7,%0\n\tjbne 1b"
 116                        : "+m"(__Atomicity_lock<0>::_S_atomicity_lock)
 117                        : /* none */
 118                        : "cc");
 119 #endif
 120
 121   __result = *__mem;
 122   *__mem = __result + __val;
 123
 124   __Atomicity_lock<0>::_S_atomicity_lock = 0;
 125
 126   return __result;
 127 }
 128
 129 #endif /* TAS / BSET */
 130
 131 static inline void
 132 __attribute__ ((__unused__))
 133 __atomic_add(volatile _Atomic_word* __mem, int __val)
 134 {
 135   // Careful: using add.l with a memory destination is not
 136   // architecturally guaranteed to be atomic.
 137   (void) __exchange_and_add(__mem, __val);
 138 }
 139
 140 #endif /* !_GLIBCXX_ATOMICITY_H */