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;
54 void proc_preempt(void)
58 LIST_ASSERT_VALID(&ProcReadyList);
59 CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
60 LIST_ASSERT_VALID(&ProcReadyList);
61 ASSERT2(CurrentProcess, "no idle proc?");
65 TRACEMSG("new proc: %p:%s", CurrentProcess, CurrentProcess ? CurrentProcess->monitor.name : "---");
69 void proc_preempt_timer(UNUSED_ARG(void *, param))
71 /* Abort if task preemption is disabled */
72 if (preempt_forbid_cnt)
77 if (!CurrentProcess->forbid_cnt)
79 TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
80 SCHED_ENQUEUE(CurrentProcess);
86 timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
87 timer_add(&preempt_timer);
90 void proc_schedule(void)
92 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
93 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
94 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
96 /* Sleeping with IRQs disabled or preemption forbidden is illegal */
98 ASSERT(preempt_forbid_cnt == 0);
100 // Will invoke proc_preempt() in interrupt context
104 void proc_yield(void)
106 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
109 SCHED_ENQUEUE(CurrentProcess);
115 void proc_entry(void (*user_entry)(void))
122 static cpustack_t idle_stack[CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)];
124 // FIXME: move this to kern/idle.c
128 * This process never dies and never sleeps. It's also quite lazy, apathic
129 * and a bit antisocial.
131 * Having an idle process costs some stack space, but simplifies the
132 * interrupt-driven preemption logic because there is always a user
133 * context to which we can return.
135 static NORETURN void idle(void)
141 proc_yield(); // FIXME: CPU_IDLE
145 void preempt_init(void)
150 irq_register(SIGUSR1, proc_preempt);
152 timer_setSoftint(&preempt_timer, proc_preempt_timer, NULL);
153 timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
154 timer_add(&preempt_timer);
156 proc_new(idle, NULL, sizeof(idle_stack), idle_stack);