1 // Low-level functions for atomic operations: m68k version -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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)
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.
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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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.
30 #include <ext/atomicity.h>
32 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
34 #if ( defined(__mc68020__) || defined(__mc68030__) \
35 || defined(__mc68040__) || defined(__mc68060__) ) \
36 && !defined(__mcpu32__)
37 // These variants support compare-and-swap.
39 __attribute__ ((__unused__))
40 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
42 register _Atomic_word __result = *__mem;
43 register _Atomic_word __temp;
44 __asm__ __volatile__ ("1: move%.l %0,%1\n\t"
48 : "=d" (__result), "=&d" (__temp), "=m" (*__mem)
49 : "d" (__val), "0" (__result), "m" (*__mem));
53 #elif defined(__rtems__)
54 // TAS/JBNE is unsafe on systems with strict priority-based scheduling.
55 // Disable interrupts, which we can do only from supervisor mode.
57 __attribute__ ((__unused__))
58 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
60 _Atomic_word __result;
61 short __level, __tmpsr;
62 __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr"
63 : "=d"(__level), "=d"(__tmpsr) : "1"(0x700));
66 *__mem = __result + __val;
67 __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));
75 struct _Atomicity_lock
77 static volatile unsigned char _S_atomicity_lock;
81 volatile unsigned char _Atomicity_lock<__inst>::_S_atomicity_lock = 0;
83 template volatile unsigned char _Atomicity_lock<0>::_S_atomicity_lock;
86 __attribute__ ((__unused__))
87 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
89 _Atomic_word __result;
91 // bset with no immediate addressing (not SMP-safe)
92 #if defined(__mcf5200__) || defined(__mcf5300__)
93 __asm__ __volatile__("1: bset.b #7,%0@\n\tjbne 1b"
95 : "a"(&_Atomicity_lock<0>::_S_atomicity_lock)
98 // CPU32 and MCF5400 support test-and-set (SMP-safe).
99 #elif defined(__mcpu32__) || defined(__mcf5400__)
100 __asm__ __volatile__("1: tas %0\n\tjbne 1b"
101 : "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
105 // Use bset with immediate addressing for 68000/68010 (not SMP-safe)
106 // NOTE: TAS is available on the 68000, but unsupported by some Amiga
107 // memory controllers.
109 __asm__ __volatile__("1: bset.b #7,%0\n\tjbne 1b"
110 : "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
116 *__mem = __result + __val;
118 _Atomicity_lock<0>::_S_atomicity_lock = 0;
123 #endif /* TAS / BSET */
126 __attribute__ ((__unused__))
127 __atomic_add(volatile _Atomic_word* __mem, int __val)
129 // Careful: using add.l with a memory destination is not
130 // architecturally guaranteed to be atomic.
131 __exchange_and_add(__mem, __val);
134 _GLIBCXX_END_NAMESPACE