never use stack variable for setjmp

-/* 
- * The contents of this file are subject to the Mozilla Public
- * License Version 1.1 (the "License"); you may not use this file
- * except in compliance with the License. You may obtain a copy of
- * the License at http://www.mozilla.org/MPL/
- * 
- * Software distributed under the License is distributed on an "AS
- * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
- * implied. See the License for the specific language governing
- * rights and limitations under the License.
- * 
- * The Original Code is the Netscape Portable Runtime library.
- * 
- * The Initial Developer of the Original Code is Netscape
- * Communications Corporation.  Portions created by Netscape are 
- * Copyright (C) 1994-2000 Netscape Communications Corporation.  All
- * Rights Reserved.
- * 
- * Contributor(s):  Silicon Graphics, Inc.
- * 
- * Portions created by SGI are Copyright (C) 2000-2001 Silicon
- * Graphics, Inc.  All Rights Reserved.
- * 
- * Alternatively, the contents of this file may be used under the
- * terms of the GNU General Public License Version 2 or later (the
- * "GPL"), in which case the provisions of the GPL are applicable 
- * instead of those above.  If you wish to allow use of your 
- * version of this file only under the terms of the GPL and not to
- * allow others to use your version of this file under the MPL,
- * indicate your decision by deleting the provisions above and
- * replace them with the notice and other provisions required by
- * the GPL.  If you do not delete the provisions above, a recipient
- * may use your version of this file under either the MPL or the
- * GPL.
- */
-
-/*
- * This file is derived directly from Netscape Communications Corporation,
- * and consists of extensive modifications made during the year(s) 1999-2000.
- */
-
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <string.h>
-#include <time.h>
-#include <errno.h>
-#include "common.h"
-
-/* Global data */
-_st_vp_t _st_this_vp;           /* This VP */
-_st_thread_t *_st_this_thread;  /* Current thread */
-int _st_active_count = 0;       /* Active thread count */
-
-time_t _st_curr_time = 0;       /* Current time as returned by time(2) */
-st_utime_t _st_last_tset;       /* Last time it was fetched */
-
-int st_poll(struct pollfd *pds, int npds, st_utime_t timeout)
-{
-    struct pollfd *pd;
-    struct pollfd *epd = pds + npds;
-    _st_pollq_t pq;
-    _st_thread_t *me = _ST_CURRENT_THREAD();
-    int n;
-    
-    if (me->flags & _ST_FL_INTERRUPT) {
-        me->flags &= ~_ST_FL_INTERRUPT;
-        errno = EINTR;
-        return -1;
-    }
-    
-    if ((*_st_eventsys->pollset_add)(pds, npds) < 0) {
-        return -1;
-    }
-    
-    pq.pds = pds;
-    pq.npds = npds;
-    pq.thread = me;
-    pq.on_ioq = 1;
-    _ST_ADD_IOQ(pq);
-    if (timeout != ST_UTIME_NO_TIMEOUT) {
-        _ST_ADD_SLEEPQ(me, timeout);
-    }
-    me->state = _ST_ST_IO_WAIT;
-    
-    _ST_SWITCH_CONTEXT(me);
-    
-    n = 0;
-    if (pq.on_ioq) {
-        /* If we timed out, the pollq might still be on the ioq. Remove it */
-        _ST_DEL_IOQ(pq);
-        (*_st_eventsys->pollset_del)(pds, npds);
-    } else {
-        /* Count the number of ready descriptors */
-        for (pd = pds; pd < epd; pd++) {
-            if (pd->revents) {
-                n++;
-            }
-        }
-    }
-    
-    if (me->flags & _ST_FL_INTERRUPT) {
-        me->flags &= ~_ST_FL_INTERRUPT;
-        errno = EINTR;
-        return -1;
-    }
-    
-    return n;
-}
-
-void _st_vp_schedule(void)
-{
-    _st_thread_t *trd;
-    
-    if (_ST_RUNQ.next != &_ST_RUNQ) {
-        /* Pull thread off of the run queue */
-        trd = _ST_THREAD_PTR(_ST_RUNQ.next);
-        _ST_DEL_RUNQ(trd);
-    } else {
-        /* If there are no threads to run, switch to the idle thread */
-        trd = _st_this_vp.idle_thread;
-    }
-    ST_ASSERT(trd->state == _ST_ST_RUNNABLE);
-    
-    /* Resume the thread */
-    trd->state = _ST_ST_RUNNING;
-    _ST_RESTORE_CONTEXT(trd);
-}
-
-/*
- * Initialize this Virtual Processor
- */
-int st_init(void)
-{
-    _st_thread_t *trd;
-    
-    if (_st_active_count) {
-        /* Already initialized */
-        return 0;
-    }
-    
-    /* We can ignore return value here */
-    st_set_eventsys(ST_EVENTSYS_DEFAULT);
-    
-    if (_st_io_init() < 0) {
-        return -1;
-    }
-    
-    memset(&_st_this_vp, 0, sizeof(_st_vp_t));
-    
-    ST_INIT_CLIST(&_ST_RUNQ);
-    ST_INIT_CLIST(&_ST_IOQ);
-    ST_INIT_CLIST(&_ST_ZOMBIEQ);
-#ifdef DEBUG
-    ST_INIT_CLIST(&_ST_THREADQ);
-#endif
-    
-    if ((*_st_eventsys->init)() < 0) {
-        return -1;
-    }
-    
-    _st_this_vp.pagesize = getpagesize();
-    _st_this_vp.last_clock = st_utime();
-    
-    /*
-    * Create idle thread
-    */
-    _st_this_vp.idle_thread = st_thread_create(_st_idle_thread_start, NULL, 0, 0);
-    if (!_st_this_vp.idle_thread) {
-        return -1;
-    }
-    _st_this_vp.idle_thread->flags = _ST_FL_IDLE_THREAD;
-    _st_active_count--;
-    _ST_DEL_RUNQ(_st_this_vp.idle_thread);
-    
-    /*
-    * Initialize primordial thread
-    */
-    trd = (_st_thread_t *) calloc(1, sizeof(_st_thread_t) +
-    (ST_KEYS_MAX * sizeof(void *)));
-    if (!trd) {
-        return -1;
-    }
-    trd->private_data = (void **) (trd + 1);
-    trd->state = _ST_ST_RUNNING;
-    trd->flags = _ST_FL_PRIMORDIAL;
-    _ST_SET_CURRENT_THREAD(trd);
-    _st_active_count++;
-#ifdef DEBUG
-    _ST_ADD_THREADQ(trd);
-#endif
-    
-    return 0;
-}
-
-#ifdef ST_SWITCH_CB
-st_switch_cb_t st_set_switch_in_cb(st_switch_cb_t cb)
-{
-    st_switch_cb_t ocb = _st_this_vp.switch_in_cb;
-    _st_this_vp.switch_in_cb = cb;
-    return ocb;
-}
-
-st_switch_cb_t st_set_switch_out_cb(st_switch_cb_t cb)
-{
-    st_switch_cb_t ocb = _st_this_vp.switch_out_cb;
-    _st_this_vp.switch_out_cb = cb;
-    return ocb;
-}
-#endif
-
-/*
- * Start function for the idle thread
- */
-/* ARGSUSED */
-void *_st_idle_thread_start(void *arg)
-{
-    _st_thread_t *me = _ST_CURRENT_THREAD();
-    
-    while (_st_active_count > 0) {
-        /* Idle vp till I/O is ready or the smallest timeout expired */
-        _ST_VP_IDLE();
-        
-        /* Check sleep queue for expired threads */
-        _st_vp_check_clock();
-        
-        me->state = _ST_ST_RUNNABLE;
-        _ST_SWITCH_CONTEXT(me);
-    }
-    
-    /* No more threads */
-    exit(0);
-    
-    /* NOTREACHED */
-    return NULL;
-}
-
-void st_thread_exit(void *retval)
-{
-    _st_thread_t *trd = _ST_CURRENT_THREAD();
-    
-    trd->retval = retval;
-    _st_thread_cleanup(trd);
-    _st_active_count--;
-    if (trd->term) {
-        /* Put thread on the zombie queue */
-        trd->state = _ST_ST_ZOMBIE;
-        _ST_ADD_ZOMBIEQ(trd);
-        
-        /* Notify on our termination condition variable */
-        st_cond_signal(trd->term);
-        
-        /* Switch context and come back later */
-        _ST_SWITCH_CONTEXT(trd);
-        
-        /* Continue the cleanup */
-        st_cond_destroy(trd->term);
-        trd->term = NULL;
-    }
-    
-#ifdef DEBUG
-    _ST_DEL_THREADQ(trd);
-#endif
-    
-    if (!(trd->flags & _ST_FL_PRIMORDIAL)) {
-        _st_stack_free(trd->stack);
-    }
-    
-    /* Find another thread to run */
-    _ST_SWITCH_CONTEXT(trd);
-    /* Not going to land here */
-}
-
-int st_thread_join(_st_thread_t *trd, void **retvalp)
-{
-    _st_cond_t *term = trd->term;
-    
-    /* Can't join a non-joinable thread */
-    if (term == NULL) {
-        errno = EINVAL;
-        return -1;
-    }
-    if (_ST_CURRENT_THREAD() == trd) {
-        errno = EDEADLK;
-        return -1;
-    }
-    
-    /* Multiple threads can't wait on the same joinable thread */
-    if (term->wait_q.next != &term->wait_q) {
-        errno = EINVAL;
-        return -1;
-    }
-    
-    while (trd->state != _ST_ST_ZOMBIE) {
-        if (st_cond_timedwait(term, ST_UTIME_NO_TIMEOUT) != 0) {
-            return -1;
-        }
-    }
-    
-    if (retvalp) {
-        *retvalp = trd->retval;
-    }
-    
-    /*
-    * Remove target thread from the zombie queue and make it runnable.
-    * When it gets scheduled later, it will do the clean up.
-    */
-    trd->state = _ST_ST_RUNNABLE;
-    _ST_DEL_ZOMBIEQ(trd);
-    _ST_ADD_RUNQ(trd);
-    
-    return 0;
-}
-
-void _st_thread_main(void)
-{
-    _st_thread_t *trd = _ST_CURRENT_THREAD();
-    
-    /*
-    * Cap the stack by zeroing out the saved return address register
-    * value. This allows some debugging/profiling tools to know when
-    * to stop unwinding the stack. It's a no-op on most platforms.
-    */
-    MD_CAP_STACK(&trd);
-    
-    /* Run thread main */
-    trd->retval = (*trd->start)(trd->arg);
-    
-    /* All done, time to go away */
-    st_thread_exit(trd->retval);
-}
-
-/*
- * Insert "thread" into the timeout heap, in the position
- * specified by thread->heap_index.  See docs/timeout_heap.txt
- * for details about the timeout heap.
- */
-static _st_thread_t **heap_insert(_st_thread_t *trd)
-{
-    int target = trd->heap_index;
-    int s = target;
-    _st_thread_t **p = &_ST_SLEEPQ;
-    int bits = 0;
-    int bit;
-    int index = 1;
-    
-    while (s) {
-        s >>= 1;
-        bits++;
-    }
-    
-    for (bit = bits - 2; bit >= 0; bit--) {
-        if (trd->due < (*p)->due) {
-            _st_thread_t *t = *p;
-            trd->left = t->left;
-            trd->right = t->right;
-            *p = trd;
-            trd->heap_index = index;
-            trd = t;
-        }
-        index <<= 1;
-        if (target & (1 << bit)) {
-            p = &((*p)->right);
-            index |= 1;
-        } else {
-            p = &((*p)->left);
-        }
-    }
-    
-    trd->heap_index = index;
-    *p = trd;
-    trd->left = trd->right = NULL;
-    
-    return p;
-}
-
-/*
- * Delete "thread" from the timeout heap.
- */
-static void heap_delete(_st_thread_t *trd) 
-{
-    _st_thread_t *t, **p;
-    int bits = 0;
-    int s, bit;
-    
-    /* First find and unlink the last heap element */
-    p = &_ST_SLEEPQ;
-    s = _ST_SLEEPQ_SIZE;
-    while (s) {
-        s >>= 1;
-        bits++;
-    }
-    
-    for (bit = bits - 2; bit >= 0; bit--) {
-        if (_ST_SLEEPQ_SIZE & (1 << bit)) {
-            p = &((*p)->right);
-        } else {
-            p = &((*p)->left);
-        }
-    }
-    
-    t = *p;
-    *p = NULL;
-    --_ST_SLEEPQ_SIZE;
-    if (t != trd) {
-        /*
-        * Insert the unlinked last element in place of the element we are deleting
-        */
-        t->heap_index = trd->heap_index;
-        p = heap_insert(t);
-        t = *p;
-        t->left = trd->left;
-        t->right = trd->right;
-        
-        /*
-        * Reestablish the heap invariant.
-        */
-        for (;;) {
-            _st_thread_t *y; /* The younger child */
-            int index_tmp;
-            
-            if (t->left == NULL) {
-                break;
-            } else if (t->right == NULL) {
-                y = t->left;
-            } else if (t->left->due < t->right->due) {
-                y = t->left;
-            } else {
-                y = t->right;
-            }
-            
-            if (t->due > y->due) {
-                _st_thread_t *tl = y->left;
-                _st_thread_t *tr = y->right;
-                *p = y;
-                if (y == t->left) {
-                    y->left = t;
-                    y->right = t->right;
-                    p = &y->left;
-                } else {
-                    y->left = t->left;
-                    y->right = t;
-                    p = &y->right;
-                }
-                t->left = tl;
-                t->right = tr;
-                index_tmp = t->heap_index;
-                t->heap_index = y->heap_index;
-                y->heap_index = index_tmp;
-            } else {
-                break;
-            }
-        }
-    }
-    
-    trd->left = trd->right = NULL;
-}
-
-void _st_add_sleep_q(_st_thread_t *trd, st_utime_t timeout)
-{
-    trd->due = _ST_LAST_CLOCK + timeout;
-    trd->flags |= _ST_FL_ON_SLEEPQ;
-    trd->heap_index = ++_ST_SLEEPQ_SIZE;
-    heap_insert(trd);
-}
-
-void _st_del_sleep_q(_st_thread_t *trd)
-{
-    heap_delete(trd);
-    trd->flags &= ~_ST_FL_ON_SLEEPQ;
-}
-
-void _st_vp_check_clock(void)
-{
-    _st_thread_t *trd;
-    st_utime_t elapsed, now;
-    
-    now = st_utime();
-    elapsed = now - _ST_LAST_CLOCK;
-    _ST_LAST_CLOCK = now;
-    
-    if (_st_curr_time && now - _st_last_tset > 999000) {
-        _st_curr_time = time(NULL);
-        _st_last_tset = now;
-    }
-    
-    while (_ST_SLEEPQ != NULL) {
-        trd = _ST_SLEEPQ;
-        ST_ASSERT(trd->flags & _ST_FL_ON_SLEEPQ);
-        if (trd->due > now) {
-            break;
-        }
-        _ST_DEL_SLEEPQ(trd);
-        
-        /* If thread is waiting on condition variable, set the time out flag */
-        if (trd->state == _ST_ST_COND_WAIT) {
-            trd->flags |= _ST_FL_TIMEDOUT;
-        }
-        
-        /* Make thread runnable */
-        ST_ASSERT(!(trd->flags & _ST_FL_IDLE_THREAD));
-        trd->state = _ST_ST_RUNNABLE;
-        _ST_ADD_RUNQ(trd);
-    }
-}
-
-void st_thread_interrupt(_st_thread_t* trd)
-{
-    /* If thread is already dead */
-    if (trd->state == _ST_ST_ZOMBIE) {
-        return;
-    }
-    
-    trd->flags |= _ST_FL_INTERRUPT;
-    
-    if (trd->state == _ST_ST_RUNNING || trd->state == _ST_ST_RUNNABLE) {
-        return;
-    }
-    
-    if (trd->flags & _ST_FL_ON_SLEEPQ) {
-        _ST_DEL_SLEEPQ(trd);
-    }
-    
-    /* Make thread runnable */
-    trd->state = _ST_ST_RUNNABLE;
-    _ST_ADD_RUNQ(trd);
-}
-
-_st_thread_t *st_thread_create(void *(*start)(void *arg), void *arg, int joinable, int stk_size)
-{
-    _st_thread_t *trd;
-    _st_stack_t *stack;
-    void **ptds;
-    char *sp;
-    
-    /* Adjust stack size */
-    if (stk_size == 0) {
-        stk_size = ST_DEFAULT_STACK_SIZE;
-    }
-    stk_size = ((stk_size + _ST_PAGE_SIZE - 1) / _ST_PAGE_SIZE) * _ST_PAGE_SIZE;
-    stack = _st_stack_new(stk_size);
-    if (!stack) {
-        return NULL;
-    }
-    
-    /* Allocate thread object and per-thread data off the stack */
-#if defined (MD_STACK_GROWS_DOWN)
-    sp = stack->stk_top;
-    /*
-    * The stack segment is split in the middle. The upper half is used
-    * as backing store for the register stack which grows upward.
-    * The lower half is used for the traditional memory stack which
-    * grows downward. Both stacks start in the middle and grow outward
-    * from each other.
-    */
-    /**
-    The below comments is by winlin:
-    The Stack public structure:
-        +--------------------------------------------------------------+
-        |                         stack                                |
-        +--------------------------------------------------------------+
-       bottom                                                         top
-    The code bellow use the stack as:
-        +-----------------+-----------------+-------------+------------+
-        | stack of thread |pad+align(128B+) |thread(336B) | keys(128B) |
-        +-----------------+-----------------+-------------+------------+
-       bottom            sp                trd           ptds         top
-               (context[0].__jmpbuf.sp)             (private_data)
-    */
-    sp = sp - (ST_KEYS_MAX * sizeof(void *));
-    ptds = (void **) sp;
-    sp = sp - sizeof(_st_thread_t);
-    trd = (_st_thread_t *) sp;
-    
-    /* Make stack 64-byte aligned */
-    if ((unsigned long)sp & 0x3f) {
-        sp = sp - ((unsigned long)sp & 0x3f);
-    }
-    stack->sp = sp - _ST_STACK_PAD_SIZE;
-#else
-    #error "Only Supports Stack Grown Down"
-#endif
-    
-    memset(trd, 0, sizeof(_st_thread_t));
-    memset(ptds, 0, ST_KEYS_MAX * sizeof(void *));
-    
-    /* Initialize thread */
-    trd->private_data = ptds;
-    trd->stack = stack;
-    trd->start = start;
-    trd->arg = arg;
-
-// by winlin, expand macro MD_INIT_CONTEXT
-#if defined(__mips__)
-    MD_SETJMP((trd)->context);
-    trd->context[0].__jmpbuf[0].__pc = (__ptr_t) _st_thread_main;
-    trd->context[0].__jmpbuf[0].__sp = stack->sp;
-#else
-    int ret_setjmp = 0;
-    if ((ret_setjmp = MD_SETJMP((trd)->context)) != 0) {
-        _st_thread_main();
-    }
-    MD_GET_SP(trd) = (long) (stack->sp);
-#endif
-    
-    /* If thread is joinable, allocate a termination condition variable */
-    if (joinable) {
-        trd->term = st_cond_new();
-        if (trd->term == NULL) {
-            _st_stack_free(trd->stack);
-            return NULL;
-        }
-    }
-    
-    /* Make thread runnable */
-    trd->state = _ST_ST_RUNNABLE;
-    _st_active_count++;
-    _ST_ADD_RUNQ(trd);
-#ifdef DEBUG
-    _ST_ADD_THREADQ(trd);
-#endif
-    
-    return trd;
-}
-
-_st_thread_t *st_thread_self(void)
-{
-    return _ST_CURRENT_THREAD();
-}
-
-#ifdef DEBUG
-/* ARGSUSED */
-void _st_show_thread_stack(_st_thread_t *trd, const char *messg)
-{
-}
-
-/* To be set from debugger */
-int _st_iterate_threads_flag = 0;
-
-void _st_iterate_threads(void)
-{
-    static _st_thread_t *trd = NULL;
-    static jmp_buf orig_jb, save_jb;
-    _st_clist_t *q;
-    
-    if (!_st_iterate_threads_flag) {
-        if (trd) {
-            memcpy(trd->context, save_jb, sizeof(jmp_buf));
-            MD_LONGJMP(orig_jb, 1);
-        }
-        return;
-    }
-    
-    if (trd) {
-        memcpy(trd->context, save_jb, sizeof(jmp_buf));
-        _st_show_thread_stack(trd, NULL);
-    } else {
-        if (MD_SETJMP(orig_jb)) {
-            _st_iterate_threads_flag = 0;
-            trd = NULL;
-            _st_show_thread_stack(trd, "Iteration completed");
-            return;
-        }
-        trd = _ST_CURRENT_THREAD();
-        _st_show_thread_stack(trd, "Iteration started");
-    }
-    
-    q = trd->tlink.next;
-    if (q == &_ST_THREADQ) {
-        q = q->next;
-    }
-    ST_ASSERT(q != &_ST_THREADQ);
-    trd = _ST_THREAD_THREADQ_PTR(q);
-    if (trd == _ST_CURRENT_THREAD()) {
-        MD_LONGJMP(orig_jb, 1);
-    }
-    memcpy(save_jb, trd->context, sizeof(jmp_buf));
-    MD_LONGJMP(trd->context, 1);
-}
-#endif /* DEBUG */
-
+/* 
+ * The contents of this file are subject to the Mozilla Public
+ * License Version 1.1 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.mozilla.org/MPL/
+ * 
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ * 
+ * The Original Code is the Netscape Portable Runtime library.
+ * 
+ * The Initial Developer of the Original Code is Netscape
+ * Communications Corporation.  Portions created by Netscape are 
+ * Copyright (C) 1994-2000 Netscape Communications Corporation.  All
+ * Rights Reserved.
+ * 
+ * Contributor(s):  Silicon Graphics, Inc.
+ * 
+ * Portions created by SGI are Copyright (C) 2000-2001 Silicon
+ * Graphics, Inc.  All Rights Reserved.
+ * 
+ * Alternatively, the contents of this file may be used under the
+ * terms of the GNU General Public License Version 2 or later (the
+ * "GPL"), in which case the provisions of the GPL are applicable 
+ * instead of those above.  If you wish to allow use of your 
+ * version of this file only under the terms of the GPL and not to
+ * allow others to use your version of this file under the MPL,
+ * indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by
+ * the GPL.  If you do not delete the provisions above, a recipient
+ * may use your version of this file under either the MPL or the
+ * GPL.
+ */
+
+/*
+ * This file is derived directly from Netscape Communications Corporation,
+ * and consists of extensive modifications made during the year(s) 1999-2000.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <time.h>
+#include <errno.h>
+#include "common.h"
+
+/* Global data */
+_st_vp_t _st_this_vp;           /* This VP */
+_st_thread_t *_st_this_thread;  /* Current thread */
+int _st_active_count = 0;       /* Active thread count */
+
+time_t _st_curr_time = 0;       /* Current time as returned by time(2) */
+st_utime_t _st_last_tset;       /* Last time it was fetched */
+
+int st_poll(struct pollfd *pds, int npds, st_utime_t timeout)
+{
+    struct pollfd *pd;
+    struct pollfd *epd = pds + npds;
+    _st_pollq_t pq;
+    _st_thread_t *me = _ST_CURRENT_THREAD();
+    int n;
+    
+    if (me->flags & _ST_FL_INTERRUPT) {
+        me->flags &= ~_ST_FL_INTERRUPT;
+        errno = EINTR;
+        return -1;
+    }
+    
+    if ((*_st_eventsys->pollset_add)(pds, npds) < 0) {
+        return -1;
+    }
+    
+    pq.pds = pds;
+    pq.npds = npds;
+    pq.thread = me;
+    pq.on_ioq = 1;
+    _ST_ADD_IOQ(pq);
+    if (timeout != ST_UTIME_NO_TIMEOUT) {
+        _ST_ADD_SLEEPQ(me, timeout);
+    }
+    me->state = _ST_ST_IO_WAIT;
+    
+    _ST_SWITCH_CONTEXT(me);
+    
+    n = 0;
+    if (pq.on_ioq) {
+        /* If we timed out, the pollq might still be on the ioq. Remove it */
+        _ST_DEL_IOQ(pq);
+        (*_st_eventsys->pollset_del)(pds, npds);
+    } else {
+        /* Count the number of ready descriptors */
+        for (pd = pds; pd < epd; pd++) {
+            if (pd->revents) {
+                n++;
+            }
+        }
+    }
+    
+    if (me->flags & _ST_FL_INTERRUPT) {
+        me->flags &= ~_ST_FL_INTERRUPT;
+        errno = EINTR;
+        return -1;
+    }
+    
+    return n;
+}
+
+void _st_vp_schedule(void)
+{
+    _st_thread_t *trd;
+    
+    if (_ST_RUNQ.next != &_ST_RUNQ) {
+        /* Pull thread off of the run queue */
+        trd = _ST_THREAD_PTR(_ST_RUNQ.next);
+        _ST_DEL_RUNQ(trd);
+    } else {
+        /* If there are no threads to run, switch to the idle thread */
+        trd = _st_this_vp.idle_thread;
+    }
+    ST_ASSERT(trd->state == _ST_ST_RUNNABLE);
+    
+    /* Resume the thread */
+    trd->state = _ST_ST_RUNNING;
+    _ST_RESTORE_CONTEXT(trd);
+}
+
+/*
+ * Initialize this Virtual Processor
+ */
+int st_init(void)
+{
+    _st_thread_t *trd;
+    
+    if (_st_active_count) {
+        /* Already initialized */
+        return 0;
+    }
+    
+    /* We can ignore return value here */
+    st_set_eventsys(ST_EVENTSYS_DEFAULT);
+    
+    if (_st_io_init() < 0) {
+        return -1;
+    }
+    
+    memset(&_st_this_vp, 0, sizeof(_st_vp_t));
+    
+    ST_INIT_CLIST(&_ST_RUNQ);
+    ST_INIT_CLIST(&_ST_IOQ);
+    ST_INIT_CLIST(&_ST_ZOMBIEQ);
+#ifdef DEBUG
+    ST_INIT_CLIST(&_ST_THREADQ);
+#endif
+    
+    if ((*_st_eventsys->init)() < 0) {
+        return -1;
+    }
+    
+    _st_this_vp.pagesize = getpagesize();
+    _st_this_vp.last_clock = st_utime();
+    
+    /*
+    * Create idle thread
+    */
+    _st_this_vp.idle_thread = st_thread_create(_st_idle_thread_start, NULL, 0, 0);
+    if (!_st_this_vp.idle_thread) {
+        return -1;
+    }
+    _st_this_vp.idle_thread->flags = _ST_FL_IDLE_THREAD;
+    _st_active_count--;
+    _ST_DEL_RUNQ(_st_this_vp.idle_thread);
+    
+    /*
+    * Initialize primordial thread
+    */
+    trd = (_st_thread_t *) calloc(1, sizeof(_st_thread_t) +
+    (ST_KEYS_MAX * sizeof(void *)));
+    if (!trd) {
+        return -1;
+    }
+    trd->private_data = (void **) (trd + 1);
+    trd->state = _ST_ST_RUNNING;
+    trd->flags = _ST_FL_PRIMORDIAL;
+    _ST_SET_CURRENT_THREAD(trd);
+    _st_active_count++;
+#ifdef DEBUG
+    _ST_ADD_THREADQ(trd);
+#endif
+    
+    return 0;
+}
+
+#ifdef ST_SWITCH_CB
+st_switch_cb_t st_set_switch_in_cb(st_switch_cb_t cb)
+{
+    st_switch_cb_t ocb = _st_this_vp.switch_in_cb;
+    _st_this_vp.switch_in_cb = cb;
+    return ocb;
+}
+
+st_switch_cb_t st_set_switch_out_cb(st_switch_cb_t cb)
+{
+    st_switch_cb_t ocb = _st_this_vp.switch_out_cb;
+    _st_this_vp.switch_out_cb = cb;
+    return ocb;
+}
+#endif
+
+/*
+ * Start function for the idle thread
+ */
+/* ARGSUSED */
+void *_st_idle_thread_start(void *arg)
+{
+    _st_thread_t *me = _ST_CURRENT_THREAD();
+    
+    while (_st_active_count > 0) {
+        /* Idle vp till I/O is ready or the smallest timeout expired */
+        _ST_VP_IDLE();
+        
+        /* Check sleep queue for expired threads */
+        _st_vp_check_clock();
+        
+        me->state = _ST_ST_RUNNABLE;
+        _ST_SWITCH_CONTEXT(me);
+    }
+    
+    /* No more threads */
+    exit(0);
+    
+    /* NOTREACHED */
+    return NULL;
+}
+
+void st_thread_exit(void *retval)
+{
+    _st_thread_t *trd = _ST_CURRENT_THREAD();
+    
+    trd->retval = retval;
+    _st_thread_cleanup(trd);
+    _st_active_count--;
+    if (trd->term) {
+        /* Put thread on the zombie queue */
+        trd->state = _ST_ST_ZOMBIE;
+        _ST_ADD_ZOMBIEQ(trd);
+        
+        /* Notify on our termination condition variable */
+        st_cond_signal(trd->term);
+        
+        /* Switch context and come back later */
+        _ST_SWITCH_CONTEXT(trd);
+        
+        /* Continue the cleanup */
+        st_cond_destroy(trd->term);
+        trd->term = NULL;
+    }
+    
+#ifdef DEBUG
+    _ST_DEL_THREADQ(trd);
+#endif
+    
+    if (!(trd->flags & _ST_FL_PRIMORDIAL)) {
+        _st_stack_free(trd->stack);
+    }
+    
+    /* Find another thread to run */
+    _ST_SWITCH_CONTEXT(trd);
+    /* Not going to land here */
+}
+
+int st_thread_join(_st_thread_t *trd, void **retvalp)
+{
+    _st_cond_t *term = trd->term;
+    
+    /* Can't join a non-joinable thread */
+    if (term == NULL) {
+        errno = EINVAL;
+        return -1;
+    }
+    if (_ST_CURRENT_THREAD() == trd) {
+        errno = EDEADLK;
+        return -1;
+    }
+    
+    /* Multiple threads can't wait on the same joinable thread */
+    if (term->wait_q.next != &term->wait_q) {
+        errno = EINVAL;
+        return -1;
+    }
+    
+    while (trd->state != _ST_ST_ZOMBIE) {
+        if (st_cond_timedwait(term, ST_UTIME_NO_TIMEOUT) != 0) {
+            return -1;
+        }
+    }
+    
+    if (retvalp) {
+        *retvalp = trd->retval;
+    }
+    
+    /*
+    * Remove target thread from the zombie queue and make it runnable.
+    * When it gets scheduled later, it will do the clean up.
+    */
+    trd->state = _ST_ST_RUNNABLE;
+    _ST_DEL_ZOMBIEQ(trd);
+    _ST_ADD_RUNQ(trd);
+    
+    return 0;
+}
+
+void _st_thread_main(void)
+{
+    _st_thread_t *trd = _ST_CURRENT_THREAD();
+    
+    /*
+    * Cap the stack by zeroing out the saved return address register
+    * value. This allows some debugging/profiling tools to know when
+    * to stop unwinding the stack. It's a no-op on most platforms.
+    */
+    MD_CAP_STACK(&trd);
+    
+    /* Run thread main */
+    trd->retval = (*trd->start)(trd->arg);
+    
+    /* All done, time to go away */
+    st_thread_exit(trd->retval);
+}
+
+/*
+ * Insert "thread" into the timeout heap, in the position
+ * specified by thread->heap_index.  See docs/timeout_heap.txt
+ * for details about the timeout heap.
+ */
+static _st_thread_t **heap_insert(_st_thread_t *trd)
+{
+    int target = trd->heap_index;
+    int s = target;
+    _st_thread_t **p = &_ST_SLEEPQ;
+    int bits = 0;
+    int bit;
+    int index = 1;
+    
+    while (s) {
+        s >>= 1;
+        bits++;
+    }
+    
+    for (bit = bits - 2; bit >= 0; bit--) {
+        if (trd->due < (*p)->due) {
+            _st_thread_t *t = *p;
+            trd->left = t->left;
+            trd->right = t->right;
+            *p = trd;
+            trd->heap_index = index;
+            trd = t;
+        }
+        index <<= 1;
+        if (target & (1 << bit)) {
+            p = &((*p)->right);
+            index |= 1;
+        } else {
+            p = &((*p)->left);
+        }
+    }
+    
+    trd->heap_index = index;
+    *p = trd;
+    trd->left = trd->right = NULL;
+    
+    return p;
+}
+
+/*
+ * Delete "thread" from the timeout heap.
+ */
+static void heap_delete(_st_thread_t *trd) 
+{
+    _st_thread_t *t, **p;
+    int bits = 0;
+    int s, bit;
+    
+    /* First find and unlink the last heap element */
+    p = &_ST_SLEEPQ;
+    s = _ST_SLEEPQ_SIZE;
+    while (s) {
+        s >>= 1;
+        bits++;
+    }
+    
+    for (bit = bits - 2; bit >= 0; bit--) {
+        if (_ST_SLEEPQ_SIZE & (1 << bit)) {
+            p = &((*p)->right);
+        } else {
+            p = &((*p)->left);
+        }
+    }
+    
+    t = *p;
+    *p = NULL;
+    --_ST_SLEEPQ_SIZE;
+    if (t != trd) {
+        /*
+        * Insert the unlinked last element in place of the element we are deleting
+        */
+        t->heap_index = trd->heap_index;
+        p = heap_insert(t);
+        t = *p;
+        t->left = trd->left;
+        t->right = trd->right;
+        
+        /*
+        * Reestablish the heap invariant.
+        */
+        for (;;) {
+            _st_thread_t *y; /* The younger child */
+            int index_tmp;
+            
+            if (t->left == NULL) {
+                break;
+            } else if (t->right == NULL) {
+                y = t->left;
+            } else if (t->left->due < t->right->due) {
+                y = t->left;
+            } else {
+                y = t->right;
+            }
+            
+            if (t->due > y->due) {
+                _st_thread_t *tl = y->left;
+                _st_thread_t *tr = y->right;
+                *p = y;
+                if (y == t->left) {
+                    y->left = t;
+                    y->right = t->right;
+                    p = &y->left;
+                } else {
+                    y->left = t->left;
+                    y->right = t;
+                    p = &y->right;
+                }
+                t->left = tl;
+                t->right = tr;
+                index_tmp = t->heap_index;
+                t->heap_index = y->heap_index;
+                y->heap_index = index_tmp;
+            } else {
+                break;
+            }
+        }
+    }
+    
+    trd->left = trd->right = NULL;
+}
+
+void _st_add_sleep_q(_st_thread_t *trd, st_utime_t timeout)
+{
+    trd->due = _ST_LAST_CLOCK + timeout;
+    trd->flags |= _ST_FL_ON_SLEEPQ;
+    trd->heap_index = ++_ST_SLEEPQ_SIZE;
+    heap_insert(trd);
+}
+
+void _st_del_sleep_q(_st_thread_t *trd)
+{
+    heap_delete(trd);
+    trd->flags &= ~_ST_FL_ON_SLEEPQ;
+}
+
+void _st_vp_check_clock(void)
+{
+    _st_thread_t *trd;
+    st_utime_t elapsed, now;
+    
+    now = st_utime();
+    elapsed = now - _ST_LAST_CLOCK;
+    _ST_LAST_CLOCK = now;
+    
+    if (_st_curr_time && now - _st_last_tset > 999000) {
+        _st_curr_time = time(NULL);
+        _st_last_tset = now;
+    }
+    
+    while (_ST_SLEEPQ != NULL) {
+        trd = _ST_SLEEPQ;
+        ST_ASSERT(trd->flags & _ST_FL_ON_SLEEPQ);
+        if (trd->due > now) {
+            break;
+        }
+        _ST_DEL_SLEEPQ(trd);
+        
+        /* If thread is waiting on condition variable, set the time out flag */
+        if (trd->state == _ST_ST_COND_WAIT) {
+            trd->flags |= _ST_FL_TIMEDOUT;
+        }
+        
+        /* Make thread runnable */
+        ST_ASSERT(!(trd->flags & _ST_FL_IDLE_THREAD));
+        trd->state = _ST_ST_RUNNABLE;
+        _ST_ADD_RUNQ(trd);
+    }
+}
+
+void st_thread_interrupt(_st_thread_t* trd)
+{
+    /* If thread is already dead */
+    if (trd->state == _ST_ST_ZOMBIE) {
+        return;
+    }
+    
+    trd->flags |= _ST_FL_INTERRUPT;
+    
+    if (trd->state == _ST_ST_RUNNING || trd->state == _ST_ST_RUNNABLE) {
+        return;
+    }
+    
+    if (trd->flags & _ST_FL_ON_SLEEPQ) {
+        _ST_DEL_SLEEPQ(trd);
+    }
+    
+    /* Make thread runnable */
+    trd->state = _ST_ST_RUNNABLE;
+    _ST_ADD_RUNQ(trd);
+}
+
+_st_thread_t *st_thread_create(void *(*start)(void *arg), void *arg, int joinable, int stk_size)
+{
+    _st_thread_t *trd;
+    _st_stack_t *stack;
+    void **ptds;
+    char *sp;
+    
+    /* Adjust stack size */
+    if (stk_size == 0) {
+        stk_size = ST_DEFAULT_STACK_SIZE;
+    }
+    stk_size = ((stk_size + _ST_PAGE_SIZE - 1) / _ST_PAGE_SIZE) * _ST_PAGE_SIZE;
+    stack = _st_stack_new(stk_size);
+    if (!stack) {
+        return NULL;
+    }
+    
+    /* Allocate thread object and per-thread data off the stack */
+#if defined (MD_STACK_GROWS_DOWN)
+    sp = stack->stk_top;
+    /*
+    * The stack segment is split in the middle. The upper half is used
+    * as backing store for the register stack which grows upward.
+    * The lower half is used for the traditional memory stack which
+    * grows downward. Both stacks start in the middle and grow outward
+    * from each other.
+    */
+    /**
+    The below comments is by winlin:
+    The Stack public structure:
+        +--------------------------------------------------------------+
+        |                         stack                                |
+        +--------------------------------------------------------------+
+       bottom                                                         top
+    The code bellow use the stack as:
+        +-----------------+-----------------+-------------+------------+
+        | stack of thread |pad+align(128B+) |thread(336B) | keys(128B) |
+        +-----------------+-----------------+-------------+------------+
+       bottom            sp                trd           ptds         top
+               (context[0].__jmpbuf.sp)             (private_data)
+    */
+    sp = sp - (ST_KEYS_MAX * sizeof(void *));
+    ptds = (void **) sp;
+    sp = sp - sizeof(_st_thread_t);
+    trd = (_st_thread_t *) sp;
+    
+    /* Make stack 64-byte aligned */
+    if ((unsigned long)sp & 0x3f) {
+        sp = sp - ((unsigned long)sp & 0x3f);
+    }
+    stack->sp = sp - _ST_STACK_PAD_SIZE;
+#else
+    #error "Only Supports Stack Grown Down"
+#endif
+    
+    memset(trd, 0, sizeof(_st_thread_t));
+    memset(ptds, 0, ST_KEYS_MAX * sizeof(void *));
+    
+    /* Initialize thread */
+    trd->private_data = ptds;
+    trd->stack = stack;
+    trd->start = start;
+    trd->arg = arg;
+
+// by winlin, expand macro MD_INIT_CONTEXT
+#if defined(__mips__)
+    MD_SETJMP((trd)->context);
+    trd->context[0].__jmpbuf[0].__pc = (__ptr_t) _st_thread_main;
+    trd->context[0].__jmpbuf[0].__sp = stack->sp;
+#else
+    if (MD_SETJMP((trd)->context)) {
+        _st_thread_main();
+    }
+    MD_GET_SP(trd) = (long) (stack->sp);
+#endif
+    
+    /* If thread is joinable, allocate a termination condition variable */
+    if (joinable) {
+        trd->term = st_cond_new();
+        if (trd->term == NULL) {
+            _st_stack_free(trd->stack);
+            return NULL;
+        }
+    }
+    
+    /* Make thread runnable */
+    trd->state = _ST_ST_RUNNABLE;
+    _st_active_count++;
+    _ST_ADD_RUNQ(trd);
+#ifdef DEBUG
+    _ST_ADD_THREADQ(trd);
+#endif
+    
+    return trd;
+}
+
+_st_thread_t *st_thread_self(void)
+{
+    return _ST_CURRENT_THREAD();
+}
+
+#ifdef DEBUG
+/* ARGSUSED */
+void _st_show_thread_stack(_st_thread_t *trd, const char *messg)
+{
+}
+
+/* To be set from debugger */
+int _st_iterate_threads_flag = 0;
+
+void _st_iterate_threads(void)
+{
+    static _st_thread_t *trd = NULL;
+    static jmp_buf orig_jb, save_jb;
+    _st_clist_t *q;
+    
+    if (!_st_iterate_threads_flag) {
+        if (trd) {
+            memcpy(trd->context, save_jb, sizeof(jmp_buf));
+            MD_LONGJMP(orig_jb, 1);
+        }
+        return;
+    }
+    
+    if (trd) {
+        memcpy(trd->context, save_jb, sizeof(jmp_buf));
+        _st_show_thread_stack(trd, NULL);
+    } else {
+        if (MD_SETJMP(orig_jb)) {
+            _st_iterate_threads_flag = 0;
+            trd = NULL;
+            _st_show_thread_stack(trd, "Iteration completed");
+            return;
+        }
+        trd = _ST_CURRENT_THREAD();
+        _st_show_thread_stack(trd, "Iteration started");
+    }
+    
+    q = trd->tlink.next;
+    if (q == &_ST_THREADQ) {
+        q = q->next;
+    }
+    ST_ASSERT(q != &_ST_THREADQ);
+    trd = _ST_THREAD_THREADQ_PTR(q);
+    if (trd == _ST_CURRENT_THREAD()) {
+        MD_LONGJMP(orig_jb, 1);
+    }
+    memcpy(save_jb, trd->context, sizeof(jmp_buf));
+    MD_LONGJMP(trd->context, 1);
+}
+#endif /* DEBUG */
+