atomic.h

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00001 /*
00002  * Copyright (C) 2005 Ondrej Palkovsky
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  *
00009  * - Redistributions of source code must retain the above copyright
00010  *   notice, this list of conditions and the following disclaimer.
00011  * - Redistributions in binary form must reproduce the above copyright
00012  *   notice, this list of conditions and the following disclaimer in the
00013  *   documentation and/or other materials provided with the distribution.
00014  * - The name of the author may not be used to endorse or promote products
00015  *   derived from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
00018  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00019  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00020  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
00021  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00022  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00023  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
00024  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00025  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
00026  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00027  */
00028 
00035 #ifndef __mips32_ATOMIC_H__
00036 #define __mips32_ATOMIC_H__
00037 
00038 #define atomic_inc(x)   ((void) atomic_add(x, 1))
00039 #define atomic_dec(x)   ((void) atomic_add(x, -1))
00040 
00041 #define atomic_postinc(x) (atomic_add(x, 1) - 1)
00042 #define atomic_postdec(x) (atomic_add(x, -1) + 1)
00043 
00044 #define atomic_preinc(x) atomic_add(x, 1)
00045 #define atomic_predec(x) atomic_add(x, -1)
00046 
00047 /* Atomic addition of immediate value.
00048  *
00049  * @param val Memory location to which will be the immediate value added.
00050  * @param i Signed immediate that will be added to *val.
00051  *
00052  * @return Value after addition.
00053  */
00054 static inline long atomic_add(atomic_t *val, int i)
00055 {
00056         long tmp, v;
00057 
00058         __asm__ volatile (
00059                 "1:\n"
00060                 "       ll %0, %1\n"
00061                 "       addiu %0, %0, %3\n"     /* same as addi, but never traps on overflow */
00062                 "       move %2, %0\n"
00063                 "       sc %0, %1\n"
00064                 "       beq %0, %4, 1b\n"       /* if the atomic operation failed, try again */
00065                 /*      nop     */              /* nop is inserted automatically by compiler */
00066                 : "=r" (tmp), "=m" (val->count), "=r" (v)
00067                 : "i" (i), "i" (0)
00068                 );
00069 
00070         return v;
00071 }
00072 
00073 #endif
00074 

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