2 * Copyright (c) 1998 Doug Rabson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * $FreeBSD: src/sys/i386/include/atomic.h,v 1.9.2.1 2000/07/07 00:38:47 obrien Exp $
27 * $DragonFly: src/sys/i386/include/Attic/atomic.h,v 1.5 2004/02/13 18:44:42 dillon Exp $
29 #ifndef _MACHINE_ATOMIC_H_
30 #define _MACHINE_ATOMIC_H_
33 * Various simple arithmetic on memory which is atomic in the presence
34 * of interrupts and multiple processors.
36 * atomic_set_char(P, V) (*(u_char*)(P) |= (V))
37 * atomic_clear_char(P, V) (*(u_char*)(P) &= ~(V))
38 * atomic_add_char(P, V) (*(u_char*)(P) += (V))
39 * atomic_subtract_char(P, V) (*(u_char*)(P) -= (V))
41 * atomic_set_short(P, V) (*(u_short*)(P) |= (V))
42 * atomic_clear_short(P, V) (*(u_short*)(P) &= ~(V))
43 * atomic_add_short(P, V) (*(u_short*)(P) += (V))
44 * atomic_subtract_short(P, V) (*(u_short*)(P) -= (V))
46 * atomic_set_int(P, V) (*(u_int*)(P) |= (V))
47 * atomic_clear_int(P, V) (*(u_int*)(P) &= ~(V))
48 * atomic_add_int(P, V) (*(u_int*)(P) += (V))
49 * atomic_subtract_int(P, V) (*(u_int*)(P) -= (V))
51 * atomic_set_long(P, V) (*(u_long*)(P) |= (V))
52 * atomic_clear_long(P, V) (*(u_long*)(P) &= ~(V))
53 * atomic_add_long(P, V) (*(u_long*)(P) += (V))
54 * atomic_subtract_long(P, V) (*(u_long*)(P) -= (V))
58 * The above functions are expanded inline in the statically-linked
59 * kernel. Lock prefixes are generated if an SMP kernel is being
62 * Kernel modules call real functions which are built into the kernel.
63 * This allows kernel modules to be portable between UP and SMP systems.
65 #if defined(KLD_MODULE)
66 #define ATOMIC_ASM(NAME, TYPE, OP, V) \
67 extern void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v); \
68 extern void atomic_##NAME##_##TYPE##_nonlocked(volatile u_##TYPE *p, u_##TYPE v);
70 #else /* !KLD_MODULE */
72 #define MPLOCKED "lock ; "
78 * The assembly is volatilized to demark potential before-and-after side
79 * effects if an interrupt or SMP collision were to occur. The primary
80 * atomic instructions are MP safe, the nonlocked instructions are
81 * local-interrupt-safe (so we don't depend on C 'X |= Y' generating an
82 * atomic instruction).
84 * +m - memory is read and written (=m - memory is only written)
85 * iq - integer constant or %ax/%bx/%cx/%dx (ir = int constant or any reg)
86 * (Note: byte instructions only work on %ax,%bx,%cx, or %dx). iq
87 * is good enough for our needs so don't get fancy.
90 /* egcs 1.1.2+ version */
91 #define ATOMIC_ASM(NAME, TYPE, OP, V) \
92 static __inline void \
93 atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
95 __asm __volatile(MPLOCKED OP \
99 static __inline void \
100 atomic_##NAME##_##TYPE##_nonlocked(volatile u_##TYPE *p, u_##TYPE v)\
102 __asm __volatile(MPLOCKED OP \
107 #endif /* KLD_MODULE */
109 /* egcs 1.1.2+ version */
110 ATOMIC_ASM(set, char, "orb %b2,%0", v)
111 ATOMIC_ASM(clear, char, "andb %b2,%0", ~v)
112 ATOMIC_ASM(add, char, "addb %b2,%0", v)
113 ATOMIC_ASM(subtract, char, "subb %b2,%0", v)
115 ATOMIC_ASM(set, short, "orw %w2,%0", v)
116 ATOMIC_ASM(clear, short, "andw %w2,%0", ~v)
117 ATOMIC_ASM(add, short, "addw %w2,%0", v)
118 ATOMIC_ASM(subtract, short, "subw %w2,%0", v)
120 ATOMIC_ASM(set, int, "orl %2,%0", v)
121 ATOMIC_ASM(clear, int, "andl %2,%0", ~v)
122 ATOMIC_ASM(add, int, "addl %2,%0", v)
123 ATOMIC_ASM(subtract, int, "subl %2,%0", v)
125 ATOMIC_ASM(set, long, "orl %2,%0", v)
126 ATOMIC_ASM(clear, long, "andl %2,%0", ~v)
127 ATOMIC_ASM(add, long, "addl %2,%0", v)
128 ATOMIC_ASM(subtract, long, "subl %2,%0", v)
130 #endif /* ! _MACHINE_ATOMIC_H_ */