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 2001, 2004 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
33 * \brief Simple realtime multitasking scheduler.
34 * Context switching is only done cooperatively.
36 * \version $Id: proc.c 1616 2008-08-10 19:41:26Z bernie $
37 * \author Bernie Innocenti <bernie@codewiz.org>
38 * \author Stefano Fedrigo <aleph@develer.com>
46 * The time sharing scheduler forces a task switch when the current
47 * process has exhausted its quantum.
52 * Disable preemptive task switching.
54 * The scheduler maintains a per-process nesting counter. Task switching is
55 * effectively re-enabled only when the number of calls to proc_permit()
56 * matches the number of calls to proc_forbid().
58 * Calling functions that could sleep while task switching is disabled
59 * is dangerous, although supported. Preemptive task switching is
60 * resumed while the process is sleeping and disabled again as soon as
65 void proc_forbid(void)
67 /* No need to protect against interrupts here. */
68 ++CurrentProcess->forbid_cnt;
72 * Re-enable preemptive task switching.
76 void proc_permit(void)
78 /* No need to protect against interrupts here. */
79 --CurrentProcess->forbid_cnt;