import RT-Thread RTOS 0.3.x to Google SVN

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2 bbd45198-f89e-11dd-88c7-29a3b14d5316

src/clock.c

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+/*
+ * File      : clock.c
+ * This file is part of RT-Thread RTOS
+ * COPYRIGHT (C) 2006, RT-Thread Development Team
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://openlab.rt-thread.com/license/LICENSE
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2006-03-12     Bernard      first version
+ * 2006-05-27     Bernard      add support for same priority thread schedule
+ * 2006-08-10     Bernard      remove the last rt_schedule in rt_tick_increase
+ */
+
+#include <rtthread.h>
+
+static rt_tick_t rt_tick;
+static rt_time_t rt_passed_second;
+
+extern void rt_timer_check(void);
+
+/**
+ * This function will init system tick and set it to zero.
+ * @ingroup SystemInit
+ *
+ */
+void rt_system_tick_init()
+{
+	rt_tick = 0;
+	rt_passed_second = 0;
+}
+
+/**
+ * @addtogroup Clock
+ */
+
+/*@{*/
+
+/**
+ * This function will return current tick from operating system startup
+ *
+ * @return current tick
+ */
+rt_tick_t rt_tick_get()
+{
+	/* return the global tick */
+	return rt_tick;
+}
+
+/**
+ * This function will notify kernel there is one tick passed. Normally, 
+ * this function is invoked by clock ISR.
+ */
+void rt_tick_increase()
+{
+	struct rt_thread* thread;
+
+	/* increase the global tick */
+	++ rt_tick;
+
+	if (rt_tick % RT_TICK_PER_SECOND == 0)
+	{
+		++rt_passed_second;
+	}
+
+	/* check timer  */
+	rt_timer_check();
+
+	/* check time slice */
+	thread = rt_thread_self();
+
+	-- thread->remaining_tick;
+	if (thread->remaining_tick == 0)
+	{
+		/* change to initialized tick */
+		thread->remaining_tick = thread->init_tick;
+
+		/* yield */
+	    rt_thread_yield();
+	}
+}
+
+/**
+ * This function will calculate the tick from millisecond.
+ *
+ * @param ms the specified millisecond
+ *
+ * @return the calculated tick
+ */
+rt_tick_t rt_tick_from_millisecond(rt_uint32_t ms)
+{
+	/* return the calculated tick */
+	return RT_TICK_PER_SECOND * (ms / 1000);
+}
+
+/*@}*/
+