<h2>Editing File: /usr/include/bind9/isc/atomic.h</h2><form method='post'><textarea name='content' class='file-edit'>/*
 * Copyright (C) Internet Systems Consortium, Inc. (&quot;ISC&quot;)
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */


#ifndef ISC_ATOMIC_H
#define ISC_ATOMIC_H 1

#include &lt;inttypes.h&gt;

#include &lt;isc/platform.h&gt;
#include &lt;isc/types.h&gt;

#ifdef ISC_PLATFORM_USEGCCASM
/*
 * This routine atomically increments the value stored in 'p' by 'val', and
 * returns the previous value.
 */
static __inline__ int32_t
isc_atomic_xadd(int32_t *p, int32_t val) {
	int32_t prev = val;

	__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
		&quot;lock;&quot;
#endif
		&quot;xadd %0, %1&quot;
		:&quot;=q&quot;(prev)
		:&quot;m&quot;(*p), &quot;0&quot;(prev)
		:&quot;memory&quot;, &quot;cc&quot;);

	return (prev);
}

#ifdef ISC_PLATFORM_HAVEXADDQ
static __inline__ int64_t
isc_atomic_xaddq(int64_t *p, int64_t val) {
	int64_t prev = val;

	__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
	    &quot;lock;&quot;
#endif
	    &quot;xaddq %0, %1&quot;
	    :&quot;=q&quot;(prev)
	    :&quot;m&quot;(*p), &quot;0&quot;(prev)
	    :&quot;memory&quot;, &quot;cc&quot;);

	return (prev);
}
#endif /* ISC_PLATFORM_HAVEXADDQ */

/*
 * This routine atomically stores the value 'val' in 'p' (32-bit version).
 */
static __inline__ void
isc_atomic_store(int32_t *p, int32_t val) {
	__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
		/*
		 * xchg should automatically lock memory, but we add it
		 * explicitly just in case (it at least doesn't harm)
		 */
		&quot;lock;&quot;
#endif

		&quot;xchgl %1, %0&quot;
		:
		: &quot;r&quot;(val), &quot;m&quot;(*p)
		: &quot;memory&quot;);
}

#ifdef ISC_PLATFORM_HAVEATOMICSTOREQ
/*
 * This routine atomically stores the value 'val' in 'p' (64-bit version).
 */
static __inline__ void
isc_atomic_storeq(int64_t *p, int64_t val) {
	__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
		/*
		 * xchg should automatically lock memory, but we add it
		 * explicitly just in case (it at least doesn't harm)
		 */
		&quot;lock;&quot;
#endif

		&quot;xchgq %1, %0&quot;
		:
		: &quot;r&quot;(val), &quot;m&quot;(*p)
		: &quot;memory&quot;);
}
#endif /* ISC_PLATFORM_HAVEATOMICSTOREQ */

/*
 * This routine atomically replaces the value in 'p' with 'val', if the
 * original value is equal to 'cmpval'.  The original value is returned in any
 * case.
 */
static __inline__ int32_t
isc_atomic_cmpxchg(int32_t *p, int32_t cmpval, int32_t val) {
	__asm__ volatile(
#ifdef ISC_PLATFORM_USETHREADS
		&quot;lock;&quot;
#endif
		&quot;cmpxchgl %1, %2&quot;
		: &quot;=a&quot;(cmpval)
		: &quot;r&quot;(val), &quot;m&quot;(*p), &quot;a&quot;(cmpval)
		: &quot;memory&quot;);

	return (cmpval);
}

#elif defined(ISC_PLATFORM_USESTDASM)
/*
 * The following are &quot;generic&quot; assembly code which implements the same
 * functionality in case the gcc extension cannot be used.  It should be
 * better to avoid inlining below, since we directly refer to specific
 * positions of the stack frame, which would not actually point to the
 * intended address in the embedded mnemonic.
 */
static int32_t
isc_atomic_xadd(int32_t *p, int32_t val) {
	(void)(p);
	(void)(val);

	__asm (
		&quot;movl 8(%ebp), %ecx\n&quot;
		&quot;movl 12(%ebp), %edx\n&quot;
#ifdef ISC_PLATFORM_USETHREADS
		&quot;lock;&quot;
#endif
		&quot;xadd %edx, (%ecx)\n&quot;

		/*
		 * set the return value directly in the register so that we
		 * can avoid guessing the correct position in the stack for a
		 * local variable.
		 */
		&quot;movl %edx, %eax&quot;
		);
}

static void
isc_atomic_store(int32_t *p, int32_t val) {
	(void)(p);
	(void)(val);

	__asm (
		&quot;movl 8(%ebp), %ecx\n&quot;
		&quot;movl 12(%ebp), %edx\n&quot;
#ifdef ISC_PLATFORM_USETHREADS
		&quot;lock;&quot;
#endif
		&quot;xchgl (%ecx), %edx\n&quot;
		);
}

static int32_t
isc_atomic_cmpxchg(int32_t *p, int32_t cmpval, int32_t val) {
	(void)(p);
	(void)(cmpval);
	(void)(val);

	__asm (
		&quot;movl 8(%ebp), %ecx\n&quot;
		&quot;movl 12(%ebp), %eax\n&quot;	/* must be %eax for cmpxchgl */
		&quot;movl 16(%ebp), %edx\n&quot;
#ifdef ISC_PLATFORM_USETHREADS
		&quot;lock;&quot;
#endif

		/*
		 * If (%ecx) == %eax then (%ecx) := %edx.
		 % %eax is set to old (%ecx), which will be the return value.
		 */
		&quot;cmpxchgl %edx, (%ecx)&quot;
		);
}
#else /* !ISC_PLATFORM_USEGCCASM &amp;&amp; !ISC_PLATFORM_USESTDASM */

#error &quot;unsupported compiler.  disable atomic ops by --disable-atomic&quot;

#endif
#endif /* ISC_ATOMIC_H */
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