150 lines
4.3 KiB
C
150 lines
4.3 KiB
C
/*
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* Thread queue with water mark
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*
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* COPYRIGHT (C) 2014-2015, Shanghai Real-Thread Technology Co., Ltd
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* http://www.rt-thread.com
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*
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* This file is part of RT-Thread (http://www.rt-thread.org)
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Change Logs:
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* Date Author Notes
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* 2014-04-16 Grissiom first version
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*/
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struct rt_watermark_queue
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{
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/* Current water level. */
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unsigned int level;
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unsigned int high_mark;
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unsigned int low_mark;
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rt_list_t suspended_threads;
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};
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/** Init the struct rt_watermark_queue.
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*/
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void rt_wm_que_init(struct rt_watermark_queue *wg,
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unsigned int low, unsigned int high);
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void rt_wm_que_set_mark(struct rt_watermark_queue *wg,
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unsigned int low, unsigned int high);
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void rt_wm_que_dump(struct rt_watermark_queue *wg);
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/* Water marks are often used in performance critical places. Benchmark shows
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* inlining functions will have 10% performance gain in some situation(for
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* example, VBus). So keep the inc/dec compact and inline. */
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/** Increase the water level.
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*
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* It should be called in the thread that want to raise the water level. If the
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* current level is above the high mark, the thread will be suspended up to
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* @timeout ticks.
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*
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* @return RT_EOK if water level increased successfully. -RT_EFULL on @timeout
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* is zero and the level is above water mark. -RT_ETIMEOUT if timeout occurred.
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*/
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rt_inline rt_err_t rt_wm_que_inc(struct rt_watermark_queue *wg,
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int timeout)
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{
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rt_base_t ilvl;
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/* Assert as early as possible. */
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if (timeout != 0)
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{
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RT_DEBUG_IN_THREAD_CONTEXT;
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}
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ilvl = rt_hw_interrupt_disable();
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while (wg->level > wg->high_mark)
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{
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rt_thread_t thread;
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if (timeout == 0)
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{
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rt_hw_interrupt_enable(ilvl);
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return -RT_EFULL;
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}
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thread = rt_thread_self();
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thread->error = RT_EOK;
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rt_thread_suspend(thread);
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rt_list_insert_after(&wg->suspended_threads, &thread->tlist);
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if (timeout > 0)
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{
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rt_timer_control(&(thread->thread_timer),
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RT_TIMER_CTRL_SET_TIME,
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&timeout);
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rt_timer_start(&(thread->thread_timer));
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}
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rt_hw_interrupt_enable(ilvl);
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rt_schedule();
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if (thread->error != RT_EOK)
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return thread->error;
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ilvl = rt_hw_interrupt_disable();
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}
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wg->level++;
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if (wg->level == 0)
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{
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wg->level = ~0;
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}
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rt_hw_interrupt_enable(ilvl);
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return RT_EOK;
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}
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/** Decrease the water level.
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*
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* It should be called by the consumer that drain the water out. If the water
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* level reached low mark, all the thread suspended in this queue will be waken
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* up. It's safe to call this function in interrupt context.
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*/
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rt_inline void rt_wm_que_dec(struct rt_watermark_queue *wg)
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{
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int need_sched = 0;
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rt_base_t ilvl;
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if (wg->level == 0)
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return;
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ilvl = rt_hw_interrupt_disable();
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wg->level--;
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if (wg->level == wg->low_mark)
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{
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/* There should be spaces between the low mark and high mark, so it's
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* safe to resume all the threads. */
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while (!rt_list_isempty(&wg->suspended_threads))
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{
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rt_thread_t thread;
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thread = rt_list_entry(wg->suspended_threads.next,
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struct rt_thread,
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tlist);
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rt_thread_resume(thread);
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need_sched = 1;
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}
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}
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rt_hw_interrupt_enable(ilvl);
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if (need_sched)
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rt_schedule();
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}
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