/contrib/bind9/lib/isc/alpha/include/isc/atomic.h

  1/*
  2 * Copyright (C) 2005, 2007, 2009  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 1.7 2009/04/08 06:48:23 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 * All rights reserved.
 27 *
 28 * Redistribution and use in source and binary forms, with or without
 29 * modification, are permitted provided that the following conditions
 30 * are met:
 31 * 1. Redistributions of source code must retain the above copyright
 32 *    notice, this list of conditions and the following disclaimer.
 33 * 2. Redistributions in binary form must reproduce the above copyright
 34 *    notice, this list of conditions and the following disclaimer in the
 35 *    documentation and/or other materials provided with the distribution.
 36 *
 37 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 38 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 40 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 41 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 42 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 43 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 45 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 46 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 47 * SUCH DAMAGE.
 48 *
 49 * $FreeBSD$
 50 */
 51
 52#ifndef ISC_ATOMIC_H
 53#define ISC_ATOMIC_H 1
 54
 55#include <isc/platform.h>
 56#include <isc/types.h>
 57
 58#ifdef ISC_PLATFORM_USEOSFASM
 59#include <c_asm.h>
 60
 61#pragma intrinsic(asm)
 62
 63/*
 64 * This routine atomically increments the value stored in 'p' by 'val', and
 65 * returns the previous value.  Memory access ordering around this function
 66 * can be critical, so we add explicit memory block instructions at the
 67 * beginning and the end of it (same for other functions).
 68 */
 69static inline isc_int32_t
 70isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
 71	return (asm("mb;"
 72		    "1:"
 73		    "ldl_l %t0, 0(%a0);"	/* load old value */
 74		    "mov %t0, %v0;"		/* copy the old value */
 75		    "addl %t0, %a1, %t0;"	/* calculate new value */
 76		    "stl_c %t0, 0(%a0);"	/* attempt to store */
 77		    "beq %t0, 1b;"		/* spin if failed */
 78		    "mb;",
 79		    p, val));
 80}
 81
 82/*
 83 * This routine atomically stores the value 'val' in 'p'.
 84 */
 85static inline void
 86isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
 87	(void)asm("mb;"
 88		  "1:"
 89		  "ldl_l %t0, 0(%a0);"		/* load old value */
 90		  "mov %a1, %t0;"		/* value to store */
 91		  "stl_c %t0, 0(%a0);"		/* attempt to store */
 92		  "beq %t0, 1b;"		/* spin if failed */
 93		  "mb;",
 94		  p, val);
 95}
 96
 97/*
 98 * This routine atomically replaces the value in 'p' with 'val', if the
 99 * original value is equal to 'cmpval'.  The original value is returned in any
100 * case.
101 */
102static inline isc_int32_t
103isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
104
105	return(asm("mb;"
106		   "1:"
107		   "ldl_l %t0, 0(%a0);"		/* load old value */
108		   "mov %t0, %v0;"		/* copy the old value */
109		   "cmpeq %t0, %a1, %t0;"	/* compare */
110		   "beq %t0, 2f;"		/* exit if not equal */
111		   "mov %a2, %t0;"		/* value to store */
112		   "stl_c %t0, 0(%a0);"		/* attempt to store */
113		   "beq %t0, 1b;"		/* if it failed, spin */
114		   "2:"
115		   "mb;",
116		   p, cmpval, val));
117}
118#elif defined (ISC_PLATFORM_USEGCCASM)
119static inline isc_int32_t
120isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
121	isc_int32_t temp, prev;
122
123	__asm__ volatile(
124		"mb;"
125		"1:"
126		"ldl_l %0, %1;"			/* load old value */
127		"mov %0, %2;"			/* copy the old value */
128		"addl %0, %3, %0;"		/* calculate new value */
129		"stl_c %0, %1;"			/* attempt to store */
130		"beq %0, 1b;"			/* spin if failed */
131		"mb;"
132		: "=&r"(temp), "+m"(*p), "=&r"(prev)
133		: "r"(val)
134		: "memory");
135
136	return (prev);
137}
138
139static inline void
140isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
141	isc_int32_t temp;
142
143	__asm__ volatile(
144		"mb;"
145		"1:"
146		"ldl_l %0, %1;"			/* load old value */
147		"mov %2, %0;"			/* value to store */
148		"stl_c %0, %1;"			/* attempt to store */
149		"beq %0, 1b;"			/* if it failed, spin */
150		"mb;"
151		: "=&r"(temp), "+m"(*p)
152		: "r"(val)
153		: "memory");
154}
155
156static inline isc_int32_t
157isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
158	isc_int32_t temp, prev;
159
160	__asm__ volatile(
161		"mb;"
162		"1:"
163		"ldl_l %0, %1;"			/* load old value */
164		"mov %0, %2;"			/* copy the old value */
165		"cmpeq %0, %3, %0;"		/* compare */
166		"beq %0, 2f;"			/* exit if not equal */
167		"mov %4, %0;"			/* value to store */
168		"stl_c %0, %1;"			/* attempt to store */
169		"beq %0, 1b;"			/* if it failed, spin */
170		"2:"
171		"mb;"
172		: "=&r"(temp), "+m"(*p), "=&r"(prev)
173		: "r"(cmpval), "r"(val)
174		: "memory");
175
176	return (prev);
177}
178#else
179
180#error "unsupported compiler.  disable atomic ops by --disable-atomic"
181
182#endif
183
184#endif /* ISC_ATOMIC_H */