--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nspr/pr/src/threads/combined/prustack.c	Mon Jul 28 10:47:06 2014 +0200
@@ -0,0 +1,174 @@
+/* -*- 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/. */
+
+#include "primpl.h"
+
+/* List of free stack virtual memory chunks */
+PRLock *_pr_stackLock;
+PRCList _pr_freeStacks = PR_INIT_STATIC_CLIST(&_pr_freeStacks);
+PRIntn _pr_numFreeStacks;
+PRIntn _pr_maxFreeStacks = 4;
+
+#ifdef DEBUG
+/*
+** A variable that can be set via the debugger...
+*/
+PRBool _pr_debugStacks = PR_FALSE;
+#endif
+
+/* How much space to leave between the stacks, at each end */
+#define REDZONE		(2 << _pr_pageShift)
+
+#define _PR_THREAD_STACK_PTR(_qp) \
+    ((PRThreadStack*) ((char*) (_qp) - offsetof(PRThreadStack,links)))
+
+void _PR_InitStacks(void)
+{
+    _pr_stackLock = PR_NewLock();
+}
+
+void _PR_CleanupStacks(void)
+{
+    if (_pr_stackLock) {
+        PR_DestroyLock(_pr_stackLock);
+        _pr_stackLock = NULL;
+    }
+}
+
+/*
+** Allocate a stack for a thread.
+*/
+PRThreadStack *_PR_NewStack(PRUint32 stackSize)
+{
+    PRCList *qp;
+    PRThreadStack *ts;
+    PRThread *thr;
+
+    /*
+    ** Trim the list of free stacks. Trim it backwards, tossing out the
+    ** oldest stack found first (this way more recent stacks have a
+    ** chance of being present in the data cache).
+    */
+    PR_Lock(_pr_stackLock);
+    qp = _pr_freeStacks.prev;
+    while ((_pr_numFreeStacks > _pr_maxFreeStacks) && (qp != &_pr_freeStacks)) {
+	ts = _PR_THREAD_STACK_PTR(qp);
+	thr = _PR_THREAD_STACK_TO_PTR(ts);
+	qp = qp->prev;
+	/*
+	 * skip stacks which are still being used
+	 */
+	if (thr->no_sched)
+		continue;
+	PR_REMOVE_LINK(&ts->links);
+
+	/* Give platform OS to clear out the stack for debugging */
+	_PR_MD_CLEAR_STACK(ts);
+
+	_pr_numFreeStacks--;
+	_PR_DestroySegment(ts->seg);
+	PR_DELETE(ts);
+    }
+
+    /*
+    ** Find a free thread stack. This searches the list of free'd up
+    ** virtually mapped thread stacks.
+    */
+    qp = _pr_freeStacks.next;
+    ts = 0;
+    while (qp != &_pr_freeStacks) {
+	ts = _PR_THREAD_STACK_PTR(qp);
+	thr = _PR_THREAD_STACK_TO_PTR(ts);
+	qp = qp->next;
+	/*
+	 * skip stacks which are still being used
+	 */
+	if ((!(thr->no_sched)) && ((ts->allocSize - 2*REDZONE) >= stackSize)) {
+	    /*
+	    ** Found a stack that is not in use and is big enough. Change
+	    ** stackSize to fit it.
+	    */
+	    stackSize = ts->allocSize - 2*REDZONE;
+	    PR_REMOVE_LINK(&ts->links);
+	    _pr_numFreeStacks--;
+	    ts->links.next = 0;
+	    ts->links.prev = 0;
+	    PR_Unlock(_pr_stackLock);
+	    goto done;
+	}
+	ts = 0;
+    }
+    PR_Unlock(_pr_stackLock);
+
+    if (!ts) {
+	/* Make a new thread stack object. */
+	ts = PR_NEWZAP(PRThreadStack);
+	if (!ts) {
+	    return NULL;
+	}
+
+	/*
+	** Assign some of the virtual space to the new stack object. We
+	** may not get that piece of VM, but if nothing else we will
+	** advance the pointer so we don't collide (unless the OS screws
+	** up).
+	*/
+	ts->allocSize = stackSize + 2*REDZONE;
+	ts->seg = _PR_NewSegment(ts->allocSize, 0);
+	if (!ts->seg) {
+	    PR_DELETE(ts);
+	    return NULL;
+	}
+	}
+
+  done:
+    ts->allocBase = (char*)ts->seg->vaddr;
+    ts->flags = _PR_STACK_MAPPED;
+    ts->stackSize = stackSize;
+
+#ifdef HAVE_STACK_GROWING_UP
+    ts->stackTop = ts->allocBase + REDZONE;
+    ts->stackBottom = ts->stackTop + stackSize;
+#else
+    ts->stackBottom = ts->allocBase + REDZONE;
+    ts->stackTop = ts->stackBottom + stackSize;
+#endif
+
+    PR_LOG(_pr_thread_lm, PR_LOG_NOTICE,
+	   ("thread stack: base=0x%x limit=0x%x bottom=0x%x top=0x%x\n",
+	    ts->allocBase, ts->allocBase + ts->allocSize - 1,
+	    ts->allocBase + REDZONE,
+	    ts->allocBase + REDZONE + stackSize - 1));
+	    
+    _PR_MD_INIT_STACK(ts,REDZONE);
+
+    return ts;
+}
+
+/*
+** Free the stack for the current thread
+*/
+void _PR_FreeStack(PRThreadStack *ts)
+{
+    if (!ts) {
+	return;
+    }
+    if (ts->flags & _PR_STACK_PRIMORDIAL) {
+	PR_DELETE(ts);
+	return;
+    }
+
+    /*
+    ** Put the stack on the free list. This is done because we are still
+    ** using the stack. Next time a thread is created we will trim the
+    ** list down; it's safe to do it then because we will have had to
+    ** context switch to a live stack before another thread can be
+    ** created.
+    */
+    PR_Lock(_pr_stackLock);
+    PR_APPEND_LINK(&ts->links, _pr_freeStacks.prev);
+    _pr_numFreeStacks++;
+    PR_Unlock(_pr_stackLock);
+}