1 // Low-level functions for atomic operations: m68k version -*- C++ -*-
3 // Copyright (C) 2001, 2002 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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 #ifndef _GLIBCXX_ATOMICITY_H
31 #define _GLIBCXX_ATOMICITY_H 1
33 typedef int _Atomic_word
;
35 #if ( defined(__mc68020__) || defined(__mc68030__) \
36 || defined(__mc68040__) || defined(__mc68060__) ) \
37 && !defined(__mcpu32__)
38 // These variants support compare-and-swap.
40 static inline _Atomic_word
41 __attribute__ ((__unused__
))
42 __exchange_and_add (volatile _Atomic_word
*__mem
, int __val
)
44 register _Atomic_word __result
= *__mem
;
45 register _Atomic_word __temp
;
46 __asm__
__volatile__ ("1: move%.l %0,%1\n\t"
50 : "=d" (__result
), "=&d" (__temp
), "+m" (*__mem
)
51 : "d" (__val
), "0" (__result
)
56 #elif defined(__rtems__)
58 * TAS/JBNE is unsafe on systems with strict priority-based scheduling.
59 * Disable interrupts, which we can do only from supervisor mode.
61 static inline _Atomic_word
62 __attribute__ ((__unused__
))
63 __exchange_and_add (volatile _Atomic_word
*__mem
, int __val
)
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));
71 *__mem
= __result
+ __val
;
73 __asm__
__volatile__ ("move%.w %0,%%sr" : : "d"(__level
));
81 struct __Atomicity_lock
83 static volatile unsigned char _S_atomicity_lock
;
87 volatile unsigned char __Atomicity_lock
<__inst
>::_S_atomicity_lock
= 0;
89 template volatile unsigned char __Atomicity_lock
<0>::_S_atomicity_lock
;
91 static inline _Atomic_word
92 __attribute__ ((__unused__
))
93 __exchange_and_add (volatile _Atomic_word
*__mem
, int __val
)
95 _Atomic_word __result
;
97 // bset with no immediate addressing
98 #if defined(__mcf5200__) || defined(__mcf5300__) || defined(__mcf5400__)
99 __asm__
__volatile__("1: bset.b #7,%0@\n\tjbne 1b"
101 : "a"(&__Atomicity_lock
<0>::_S_atomicity_lock
)
104 // bset with immediate addressing
105 #elif defined(__mc68000__)
106 __asm__
__volatile__("1: bset.b #7,%0\n\tjbne 1b"
107 : "+m"(__Atomicity_lock
<0>::_S_atomicity_lock
)
111 #else // 680x0, cpu32, 5400 support test-and-set.
112 __asm__
__volatile__("1: tas %0\n\tjbne 1b"
113 : "+m"(__Atomicity_lock
<0>::_S_atomicity_lock
)
119 *__mem
= __result
+ __val
;
121 __Atomicity_lock
<0>::_S_atomicity_lock
= 0;
126 #endif /* TAS / BSET */
129 __attribute__ ((__unused__
))
130 __atomic_add (volatile _Atomic_word
* __mem
, int __val
)
132 // Careful: using add.l with a memory destination is not
133 // architecturally guaranteed to be atomic.
134 (void) __exchange_and_add (__mem
, __val
);
137 #endif /* !_GLIBCXX_ATOMICITY_H */