--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nspr/pr/src/misc/pratom.c	Mon Jul 28 10:47:06 2014 +0200
@@ -0,0 +1,379 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+/*
+**     PR Atomic operations
+*/
+
+
+#include "pratom.h"
+#include "primpl.h"
+
+#include <string.h>
+
+/*
+ * The following is a fallback implementation that emulates
+ * atomic operations for platforms without atomic operations.
+ * If a platform has atomic operations, it should define the
+ * macro _PR_HAVE_ATOMIC_OPS, and the following will not be
+ * compiled in.
+ */
+
+#if !defined(_PR_HAVE_ATOMIC_OPS)
+
+#if defined(_PR_PTHREADS) && !defined(_PR_DCETHREADS)
+/*
+ * PR_AtomicDecrement() is used in NSPR's thread-specific data
+ * destructor.  Because thread-specific data destructors may be
+ * invoked after a PR_Cleanup() call, we need an implementation
+ * of the atomic routines that doesn't need NSPR to be initialized.
+ */
+
+/*
+ * We use a set of locks for all the emulated atomic operations.
+ * By hashing on the address of the integer to be locked the
+ * contention between multiple threads should be lessened.
+ *
+ * The number of atomic locks can be set by the environment variable
+ * NSPR_ATOMIC_HASH_LOCKS
+ */
+
+/*
+ * lock counts should be a power of 2
+ */
+#define DEFAULT_ATOMIC_LOCKS	16	/* should be in sync with the number of initializers
+										below */
+#define MAX_ATOMIC_LOCKS		(4 * 1024)
+
+static pthread_mutex_t static_atomic_locks[DEFAULT_ATOMIC_LOCKS] = {
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
+        PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER };
+
+#ifdef DEBUG
+static PRInt32 static_hash_lock_counts[DEFAULT_ATOMIC_LOCKS];
+static PRInt32 *hash_lock_counts = static_hash_lock_counts;
+#endif
+
+static PRUint32	num_atomic_locks = DEFAULT_ATOMIC_LOCKS;
+static pthread_mutex_t *atomic_locks = static_atomic_locks;
+static PRUint32 atomic_hash_mask = DEFAULT_ATOMIC_LOCKS - 1;
+
+#define _PR_HASH_FOR_LOCK(ptr) 							\
+			((PRUint32) (((PRUptrdiff) (ptr) >> 2)	^	\
+						((PRUptrdiff) (ptr) >> 8)) &	\
+						atomic_hash_mask)
+
+void _PR_MD_INIT_ATOMIC()
+{
+char *eval;
+int index;
+
+
+	PR_ASSERT(PR_FloorLog2(MAX_ATOMIC_LOCKS) ==
+						PR_CeilingLog2(MAX_ATOMIC_LOCKS));
+
+	PR_ASSERT(PR_FloorLog2(DEFAULT_ATOMIC_LOCKS) ==
+							PR_CeilingLog2(DEFAULT_ATOMIC_LOCKS));
+
+	if (((eval = getenv("NSPR_ATOMIC_HASH_LOCKS")) != NULL)  &&
+		((num_atomic_locks = atoi(eval)) != DEFAULT_ATOMIC_LOCKS)) {
+
+		if (num_atomic_locks > MAX_ATOMIC_LOCKS)
+			num_atomic_locks = MAX_ATOMIC_LOCKS;
+		else if (num_atomic_locks < 1) 
+			num_atomic_locks = 1;
+		else {
+			num_atomic_locks = PR_FloorLog2(num_atomic_locks);
+			num_atomic_locks = 1L << num_atomic_locks;
+		}
+		atomic_locks = (pthread_mutex_t *) PR_Malloc(sizeof(pthread_mutex_t) *
+						num_atomic_locks);
+		if (atomic_locks) {
+			for (index = 0; index < num_atomic_locks; index++) {
+				if (pthread_mutex_init(&atomic_locks[index], NULL)) {
+						PR_DELETE(atomic_locks);
+						atomic_locks = NULL;
+						break; 
+				}
+			}
+		}
+#ifdef DEBUG
+		if (atomic_locks) {
+			hash_lock_counts = PR_CALLOC(num_atomic_locks * sizeof(PRInt32));
+			if (hash_lock_counts == NULL) {
+				PR_DELETE(atomic_locks);
+				atomic_locks = NULL;
+			}
+		}
+#endif
+		if (atomic_locks == NULL) {
+			/*
+			 *	Use statically allocated locks
+			 */
+			atomic_locks = static_atomic_locks;
+			num_atomic_locks = DEFAULT_ATOMIC_LOCKS;
+	#ifdef DEBUG
+			hash_lock_counts = static_hash_lock_counts;
+	#endif
+		}
+		atomic_hash_mask = num_atomic_locks - 1;
+	}
+	PR_ASSERT(PR_FloorLog2(num_atomic_locks) ==
+								PR_CeilingLog2(num_atomic_locks));
+}
+
+PRInt32
+_PR_MD_ATOMIC_INCREMENT(PRInt32 *val)
+{
+    PRInt32 rv;
+    PRInt32 idx = _PR_HASH_FOR_LOCK(val);
+
+    pthread_mutex_lock(&atomic_locks[idx]);
+    rv = ++(*val);
+#ifdef DEBUG
+    hash_lock_counts[idx]++;
+#endif
+    pthread_mutex_unlock(&atomic_locks[idx]);
+    return rv;
+}
+
+PRInt32
+_PR_MD_ATOMIC_ADD(PRInt32 *ptr, PRInt32 val)
+{
+    PRInt32 rv;
+    PRInt32 idx = _PR_HASH_FOR_LOCK(ptr);
+
+    pthread_mutex_lock(&atomic_locks[idx]);
+    rv = ((*ptr) += val);
+#ifdef DEBUG
+    hash_lock_counts[idx]++;
+#endif
+    pthread_mutex_unlock(&atomic_locks[idx]);
+    return rv;
+}
+
+PRInt32
+_PR_MD_ATOMIC_DECREMENT(PRInt32 *val)
+{
+    PRInt32 rv;
+    PRInt32 idx = _PR_HASH_FOR_LOCK(val);
+
+    pthread_mutex_lock(&atomic_locks[idx]);
+    rv = --(*val);
+#ifdef DEBUG
+    hash_lock_counts[idx]++;
+#endif
+    pthread_mutex_unlock(&atomic_locks[idx]);
+    return rv;
+}
+
+PRInt32
+_PR_MD_ATOMIC_SET(PRInt32 *val, PRInt32 newval)
+{
+    PRInt32 rv;
+    PRInt32 idx = _PR_HASH_FOR_LOCK(val);
+
+    pthread_mutex_lock(&atomic_locks[idx]);
+    rv = *val;
+    *val = newval;
+#ifdef DEBUG
+    hash_lock_counts[idx]++;
+#endif
+    pthread_mutex_unlock(&atomic_locks[idx]);
+    return rv;
+}
+#else  /* _PR_PTHREADS && !_PR_DCETHREADS */
+/*
+ * We use a single lock for all the emulated atomic operations.
+ * The lock contention should be acceptable.
+ */
+static PRLock *atomic_lock = NULL;
+void _PR_MD_INIT_ATOMIC(void)
+{
+    if (atomic_lock == NULL) {
+        atomic_lock = PR_NewLock();
+    }
+}
+
+PRInt32
+_PR_MD_ATOMIC_INCREMENT(PRInt32 *val)
+{
+    PRInt32 rv;
+
+    if (!_pr_initialized) {
+        _PR_ImplicitInitialization();
+    }
+    PR_Lock(atomic_lock);
+    rv = ++(*val);
+    PR_Unlock(atomic_lock);
+    return rv;
+}
+
+PRInt32
+_PR_MD_ATOMIC_ADD(PRInt32 *ptr, PRInt32 val)
+{
+    PRInt32 rv;
+
+    if (!_pr_initialized) {
+        _PR_ImplicitInitialization();
+    }
+    PR_Lock(atomic_lock);
+    rv = ((*ptr) += val);
+    PR_Unlock(atomic_lock);
+    return rv;
+}
+
+PRInt32
+_PR_MD_ATOMIC_DECREMENT(PRInt32 *val)
+{
+    PRInt32 rv;
+
+    if (!_pr_initialized) {
+        _PR_ImplicitInitialization();
+    }
+    PR_Lock(atomic_lock);
+    rv = --(*val);
+    PR_Unlock(atomic_lock);
+    return rv;
+}
+
+PRInt32
+_PR_MD_ATOMIC_SET(PRInt32 *val, PRInt32 newval)
+{
+    PRInt32 rv;
+
+    if (!_pr_initialized) {
+        _PR_ImplicitInitialization();
+    }
+    PR_Lock(atomic_lock);
+    rv = *val;
+    *val = newval;
+    PR_Unlock(atomic_lock);
+    return rv;
+}
+#endif  /* _PR_PTHREADS && !_PR_DCETHREADS */
+
+#endif  /* !_PR_HAVE_ATOMIC_OPS */
+
+void _PR_InitAtomic(void)
+{
+    _PR_MD_INIT_ATOMIC();
+}
+
+PR_IMPLEMENT(PRInt32)
+PR_AtomicIncrement(PRInt32 *val)
+{
+    return _PR_MD_ATOMIC_INCREMENT(val);
+}
+
+PR_IMPLEMENT(PRInt32)
+PR_AtomicDecrement(PRInt32 *val)
+{
+    return _PR_MD_ATOMIC_DECREMENT(val);
+}
+
+PR_IMPLEMENT(PRInt32)
+PR_AtomicSet(PRInt32 *val, PRInt32 newval)
+{
+    return _PR_MD_ATOMIC_SET(val, newval);
+}
+
+PR_IMPLEMENT(PRInt32)
+PR_AtomicAdd(PRInt32 *ptr, PRInt32 val)
+{
+    return _PR_MD_ATOMIC_ADD(ptr, val);
+}
+/*
+ * For platforms, which don't support the CAS (compare-and-swap) instruction
+ * (or an equivalent), the stack operations are implemented by use of PRLock
+ */
+
+PR_IMPLEMENT(PRStack *)
+PR_CreateStack(const char *stack_name)
+{
+PRStack *stack;
+
+    if (!_pr_initialized) {
+        _PR_ImplicitInitialization();
+    }
+
+    if ((stack = PR_NEW(PRStack)) == NULL) {
+		return NULL;
+	}
+	if (stack_name) {
+		stack->prstk_name = (char *) PR_Malloc(strlen(stack_name) + 1);
+		if (stack->prstk_name == NULL) {
+			PR_DELETE(stack);
+			return NULL;
+		}
+		strcpy(stack->prstk_name, stack_name);
+	} else
+		stack->prstk_name = NULL;
+
+#ifndef _PR_HAVE_ATOMIC_CAS
+    stack->prstk_lock = PR_NewLock();
+	if (stack->prstk_lock == NULL) {
+		PR_Free(stack->prstk_name);
+		PR_DELETE(stack);
+		return NULL;
+	}
+#endif /* !_PR_HAVE_ATOMIC_CAS */
+
+	stack->prstk_head.prstk_elem_next = NULL;
+	
+    return stack;
+}
+
+PR_IMPLEMENT(PRStatus)
+PR_DestroyStack(PRStack *stack)
+{
+	if (stack->prstk_head.prstk_elem_next != NULL) {
+		PR_SetError(PR_INVALID_STATE_ERROR, 0);
+		return PR_FAILURE;
+	}
+
+	if (stack->prstk_name)
+		PR_Free(stack->prstk_name);
+#ifndef _PR_HAVE_ATOMIC_CAS
+	PR_DestroyLock(stack->prstk_lock);
+#endif /* !_PR_HAVE_ATOMIC_CAS */
+	PR_DELETE(stack);
+
+	return PR_SUCCESS;
+}
+
+#ifndef _PR_HAVE_ATOMIC_CAS
+
+PR_IMPLEMENT(void)
+PR_StackPush(PRStack *stack, PRStackElem *stack_elem)
+{
+    PR_Lock(stack->prstk_lock);
+	stack_elem->prstk_elem_next = stack->prstk_head.prstk_elem_next;
+	stack->prstk_head.prstk_elem_next = stack_elem;
+    PR_Unlock(stack->prstk_lock);
+    return;
+}
+
+PR_IMPLEMENT(PRStackElem *)
+PR_StackPop(PRStack *stack)
+{
+PRStackElem *element;
+
+    PR_Lock(stack->prstk_lock);
+	element = stack->prstk_head.prstk_elem_next;
+	if (element != NULL) {
+		stack->prstk_head.prstk_elem_next = element->prstk_elem_next;
+		element->prstk_elem_next = NULL;	/* debugging aid */
+	}
+    PR_Unlock(stack->prstk_lock);
+    return element;
+}
+#endif /* !_PR_HAVE_ATOMIC_CAS */