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>
42 #include <kern/monitor.h>
43 #include <cpu/frame.h> // CPU_IDLE
44 #include <cpu/irq.h> // IRQ_DISABLE()...
45 #include <drv/timer.h>
46 #include <cfg/module.h>
49 int preempt_forbid_cnt;
51 static Timer preempt_timer;
54 // fwd decl from idle.c
58 void proc_preempt(void)
62 ASSERT(preempt_forbid_cnt == 0);
63 LIST_ASSERT_VALID(&ProcReadyList);
64 CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
65 ASSERT2(CurrentProcess, "no idle proc?");
69 TRACEMSG("launching %p:%s", CurrentProcess, proc_currentName());
72 void proc_preempt_timer(UNUSED_ARG(void *, param))
74 if (!preempt_forbid_cnt)
79 Process *rival = (Process *)LIST_HEAD(&ProcReadyList);
80 if (rival && rival->link.pri >= CurrentProcess->link.pri)
84 TRACEMSG("preempting %p:%s", CurrentProcess, proc_currentName());
86 SCHED_ENQUEUE(CurrentProcess);
96 timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
97 timer_add(&preempt_timer);
100 void proc_schedule(void)
102 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
103 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
104 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
106 /* Sleeping with IRQs disabled or preemption forbidden is illegal */
107 ASSERT_IRQ_ENABLED();
108 ASSERT(preempt_forbid_cnt == 0);
110 // Will invoke proc_preempt() in interrupt context
114 void proc_yield(void)
116 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
119 SCHED_ENQUEUE(CurrentProcess);
125 void proc_entry(void (*user_entry)(void))
131 void preempt_init(void)
136 irq_register(SIGUSR1, proc_preempt);
138 timer_setSoftint(&preempt_timer, proc_preempt_timer, NULL);
139 timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
140 timer_add(&preempt_timer);