4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
32 * \brief Simple preemptive multitasking scheduler.
34 * \version $Id: proc.c 1616 2008-08-10 19:41:26Z bernie $
35 * \author Bernie Innocenti <bernie@codewiz.org>
38 #include <cfg/cfg_kern.h>
40 #if CONFIG_KERN_PREEMPT
46 #include <kern/monitor.h>
47 #include <cpu/frame.h> // CPU_IDLE
48 #include <cpu/irq.h> // IRQ_DISABLE()...
49 #include <drv/timer.h>
50 #include <cfg/module.h>
51 #include <cfg/depend.h> // CONFIG_DEPEND()
53 // Check config dependencies
54 CONFIG_DEPEND(CONFIG_KERN_PREEMPT, CONFIG_KERN_SCHED && CONFIG_TIMER_EVENTS && CONFIG_KERN_IRQ);
55 CONFIG_DEPEND(CONFIG_KERN_PRI, CONFIG_KERN_PREEMPT);
59 int preempt_forbid_cnt;
61 static Timer preempt_timer;
64 // fwd decl from idle.c
68 void proc_preempt(void)
72 ASSERT(preempt_forbid_cnt == 0);
73 LIST_ASSERT_VALID(&ProcReadyList);
74 CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
75 ASSERT2(CurrentProcess, "no idle proc?");
79 TRACEMSG("launching %p:%s", CurrentProcess, proc_currentName());
82 void proc_preempt_timer(UNUSED_ARG(void *, param))
84 if (!preempt_forbid_cnt)
89 Process *rival = (Process *)LIST_HEAD(&ProcReadyList);
90 if (rival && rival->link.pri >= CurrentProcess->link.pri)
94 TRACEMSG("preempting %p:%s", CurrentProcess, proc_currentName());
96 SCHED_ENQUEUE(CurrentProcess);
106 timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
107 timer_add(&preempt_timer);
110 void proc_schedule(void)
112 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
113 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
114 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
116 /* Sleeping with IRQs disabled or preemption forbidden is illegal */
117 ASSERT_IRQ_ENABLED();
118 ASSERT(preempt_forbid_cnt == 0);
120 // Will invoke proc_preempt() in interrupt context
124 void proc_yield(void)
126 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
129 SCHED_ENQUEUE(CurrentProcess);
135 void proc_entry(void (*user_entry)(void))
141 void preempt_init(void)
146 irq_register(SIGUSR1, proc_preempt);
148 timer_setSoftint(&preempt_timer, proc_preempt_timer, NULL);
149 timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
150 timer_add(&preempt_timer);
157 #endif // CONFIG_KERN_PREEMPT