6ed00870ab
Abstracts threading from itself a bit, changes the way its queues are handled and does type hiding for that as well. Do alot here due to already required major brain surgery. Threads may now be on a run queue and a wait queue simultaneously so that the expired timer only has to wake the thread but not remove it from the wait queue which simplifies the implicit wake handling. List formats change for wait queues-- doubly-linked, not circular. Timeout queue is now singly-linked. The run queue is still circular as before. Adds a better thread slot allocator that may keep the slot marked as used regardless of the thread state. Assists in dumping special tasks that switch_thread was tasked to perform (blocking tasks). Deletes alot of code yet surprisingly, gets larger than expected. Well, I'm not not minding that for the time being-- omlettes and break a few eggs and all that. Change-Id: I0834d7bb16b2aecb2f63b58886eeda6ae4f29d59
133 lines
4.1 KiB
C
133 lines
4.1 KiB
C
/***************************************************************************
|
|
* __________ __ ___.
|
|
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
|
|
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
|
|
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
|
|
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
|
|
* \/ \/ \/ \/ \/
|
|
* $Id$
|
|
*
|
|
* Copyright (C) 2002 by Björn Stenberg
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version 2
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
|
|
* KIND, either express or implied.
|
|
*
|
|
****************************************************************************/
|
|
#include "kernel-internal.h"
|
|
#include "semaphore.h"
|
|
|
|
/****************************************************************************
|
|
* Simple semaphore functions ;)
|
|
****************************************************************************/
|
|
|
|
/* Initialize the semaphore object.
|
|
* max = maximum up count the semaphore may assume (max >= 1)
|
|
* start = initial count of semaphore (0 <= count <= max) */
|
|
void semaphore_init(struct semaphore *s, int max, int start)
|
|
{
|
|
KERNEL_ASSERT(max > 0 && start >= 0 && start <= max,
|
|
"semaphore_init->inv arg\n");
|
|
wait_queue_init(&s->queue);
|
|
s->max = max;
|
|
s->count = start;
|
|
corelock_init(&s->cl);
|
|
}
|
|
|
|
/* Down the semaphore's count or wait for 'timeout' ticks for it to go up if
|
|
* it is already 0. 'timeout' as TIMEOUT_NOBLOCK (0) will not block and may
|
|
* safely be used in an ISR. */
|
|
int semaphore_wait(struct semaphore *s, int timeout)
|
|
{
|
|
int ret = OBJ_WAIT_TIMEDOUT;
|
|
|
|
int oldlevel = disable_irq_save();
|
|
corelock_lock(&s->cl);
|
|
|
|
int count = s->count;
|
|
if(LIKELY(count > 0))
|
|
{
|
|
/* count is not zero; down it */
|
|
s->count = count - 1;
|
|
ret = OBJ_WAIT_SUCCEEDED;
|
|
}
|
|
else if(timeout != 0)
|
|
{
|
|
/* too many waits - block until count is upped... */
|
|
struct thread_entry *current = __running_self_entry();
|
|
|
|
block_thread(current, timeout, &s->queue, NULL);
|
|
corelock_unlock(&s->cl);
|
|
|
|
/* ...and turn control over to next thread */
|
|
switch_thread();
|
|
|
|
/* if explicit wake indicated; do no more */
|
|
if(LIKELY(!wait_queue_ptr(current)))
|
|
return OBJ_WAIT_SUCCEEDED;
|
|
|
|
disable_irq();
|
|
corelock_lock(&s->cl);
|
|
|
|
/* see if anyone got us after the expired wait */
|
|
if(wait_queue_try_remove(current))
|
|
{
|
|
count = s->count;
|
|
if(count > 0)
|
|
{
|
|
/* down it lately */
|
|
s->count = count - 1;
|
|
ret = OBJ_WAIT_SUCCEEDED;
|
|
}
|
|
}
|
|
}
|
|
/* else just polling it */
|
|
|
|
corelock_unlock(&s->cl);
|
|
restore_irq(oldlevel);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* Up the semaphore's count and release any thread waiting at the head of the
|
|
* queue. The count is saturated to the value of the 'max' parameter specified
|
|
* in 'semaphore_init'. */
|
|
void semaphore_release(struct semaphore *s)
|
|
{
|
|
unsigned int result = THREAD_NONE;
|
|
|
|
int oldlevel = disable_irq_save();
|
|
corelock_lock(&s->cl);
|
|
|
|
struct thread_entry *thread = WQ_THREAD_FIRST(&s->queue);
|
|
if(LIKELY(thread != NULL))
|
|
{
|
|
/* a thread was queued - wake it up and keep count at 0 */
|
|
KERNEL_ASSERT(s->count == 0,
|
|
"semaphore_release->threads queued but count=%d!\n", s->count);
|
|
result = wakeup_thread(thread, WAKEUP_DEFAULT);
|
|
}
|
|
else
|
|
{
|
|
int count = s->count;
|
|
if(count < s->max)
|
|
{
|
|
/* nothing waiting - up it */
|
|
s->count = count + 1;
|
|
}
|
|
}
|
|
|
|
corelock_unlock(&s->cl);
|
|
restore_irq(oldlevel);
|
|
|
|
#if defined(HAVE_PRIORITY_SCHEDULING) && defined(is_thread_context)
|
|
/* No thread switch if not thread context */
|
|
if((result & THREAD_SWITCH) && is_thread_context())
|
|
switch_thread();
|
|
#endif
|
|
(void)result;
|
|
}
|