/*
* Copyright (c) 2005 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup kernel_generic
* @{
*/
/** @file
*/
#ifndef KERN_PREEMPTION_H_
#define KERN_PREEMPTION_H_
#include <arch.h>
#include <assert.h>
#include <barrier.h>
#define PREEMPTION_INC (1 << 0)
#define PREEMPTION_DISABLED (PREEMPTION_INC <= CURRENT->preemption)
#define PREEMPTION_ENABLED (!PREEMPTION_DISABLED)
/** Increment preemption disabled counter. */
#define preemption_disable() \
do { \
CURRENT->preemption += PREEMPTION_INC; \
compiler_barrier(); \
} while (0)
/** Restores preemption but never reschedules. */
#define preemption_enable() \
do { \
assert(PREEMPTION_DISABLED); \
compiler_barrier(); \
CURRENT->preemption -= PREEMPTION_INC; \
} while (0)
#endif
/** @}
*/