1 // Low-level functions for atomic operations: m68k version -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009 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 3, 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 // 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.
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/>.
25 #include <ext/atomicity.h>
27 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
29 #if ( defined(__mc68020__) || defined(__mc68030__) \
30 || defined(__mc68040__) || defined(__mc68060__) ) \
31 && !defined(__mcpu32__)
32 // These variants support compare-and-swap.
34 __attribute__ ((__unused__))
35 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
37 register _Atomic_word __result = *__mem;
38 register _Atomic_word __temp;
39 __asm__ __volatile__ ("1: move%.l %0,%1\n\t"
43 : "=d" (__result), "=&d" (__temp), "=m" (*__mem)
44 : "d" (__val), "0" (__result), "m" (*__mem));
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.
52 __attribute__ ((__unused__))
53 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
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));
61 *__mem = __result + __val;
62 __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));
70 struct _Atomicity_lock
72 static volatile unsigned char _S_atomicity_lock;
76 volatile unsigned char _Atomicity_lock<__inst>::_S_atomicity_lock = 0;
78 template volatile unsigned char _Atomicity_lock<0>::_S_atomicity_lock;
81 __attribute__ ((__unused__))
82 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
84 _Atomic_word __result;
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"
90 : "a"(&_Atomicity_lock<0>::_S_atomicity_lock)
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)
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.
104 __asm__ __volatile__("1: bset.b #7,%0\n\tjbne 1b"
105 : "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
111 *__mem = __result + __val;
113 _Atomicity_lock<0>::_S_atomicity_lock = 0;
118 #endif /* TAS / BSET */
121 __attribute__ ((__unused__))
122 __atomic_add(volatile _Atomic_word* __mem, int __val)
124 // Careful: using add.l with a memory destination is not
125 // architecturally guaranteed to be atomic.
126 __exchange_and_add(__mem, __val);
129 _GLIBCXX_END_NAMESPACE