1/* 2 * Copyright (C) 2005, 2007 Internet Systems Consortium, Inc. ("ISC") 3 * 4 * Permission to use, copy, modify, and/or distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 9 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 10 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 11 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 12 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 13 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 14 * PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17/* $Id: atomic.h,v 1.5 2007/06/19 23:47:18 tbox Exp $ */ 18 19/* 20 * This code was written based on FreeBSD's kernel source whose copyright 21 * follows: 22 */ 23 24/*- 25 * Copyright (c) 1998 Doug Rabson. 26 * Copyright (c) 2001 Jake Burkholder. 27 * All rights reserved. 28 * 29 * Redistribution and use in source and binary forms, with or without 30 * modification, are permitted provided that the following conditions 31 * are met: 32 * 1. Redistributions of source code must retain the above copyright 33 * notice, this list of conditions and the following disclaimer. 34 * 2. Redistributions in binary form must reproduce the above copyright 35 * notice, this list of conditions and the following disclaimer in the 36 * documentation and/or other materials provided with the distribution. 37 * 38 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 39 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 41 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 42 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 43 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 44 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 46 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 47 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * 50 * from: FreeBSD: src/sys/i386/include/atomic.h,v 1.20 2001/02/11 51 * $FreeBSD: src/sys/sparc64/include/atomic.h,v 1.8 2004/05/22 00:52:16 marius Exp $ 52 */ 53 54#ifndef ISC_ATOMIC_H 55#define ISC_ATOMIC_H 1 56 57#include <isc/platform.h> 58#include <isc/types.h> 59 60#define ASI_P 0x80 /* Primary Address Space Identifier */ 61 62#ifdef ISC_PLATFORM_USEGCCASM 63 64/* 65 * This routine atomically increments the value stored in 'p' by 'val', and 66 * returns the previous value. 67 */ 68static inline isc_int32_t 69isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) { 70 isc_int32_t prev, swapped; 71 72 for (prev = *(volatile isc_int32_t *)p; ; prev = swapped) { 73 swapped = prev + val; 74 __asm__ volatile( 75 "casa [%1] %2, %3, %0" 76 : "+r"(swapped) 77 : "r"(p), "n"(ASI_P), "r"(prev)); 78 if (swapped == prev) 79 break; 80 } 81 82 return (prev); 83} 84 85/* 86 * This routine atomically stores the value 'val' in 'p'. 87 */ 88static inline void 89isc_atomic_store(isc_int32_t *p, isc_int32_t val) { 90 isc_int32_t prev, swapped; 91 92 for (prev = *(volatile isc_int32_t *)p; ; prev = swapped) { 93 swapped = val; 94 __asm__ volatile( 95 "casa [%1] %2, %3, %0" 96 : "+r"(swapped) 97 : "r"(p), "n"(ASI_P), "r"(prev) 98 : "memory"); 99 if (swapped == prev) 100 break; 101 } 102} 103 104/* 105 * This routine atomically replaces the value in 'p' with 'val', if the 106 * original value is equal to 'cmpval'. The original value is returned in any 107 * case. 108 */ 109static inline isc_int32_t 110isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) { 111 isc_int32_t temp = val; 112 113 __asm__ volatile( 114 "casa [%1] %2, %3, %0" 115 : "+r"(temp) 116 : "r"(p), "n"(ASI_P), "r"(cmpval)); 117 118 return (temp); 119} 120 121#else /* ISC_PLATFORM_USEGCCASM */ 122 123#error "unsupported compiler. disable atomic ops by --disable-atomic" 124 125#endif /* ISC_PLATFORM_USEGCCASM */ 126 127#endif /* ISC_ATOMIC_H */ 128