/*
* Copyright (c) 2001-2004 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_time
* @{
*/
/**
* @file
* @brief Active delay function.
*/
#include <time/delay.h>
#include <proc/thread.h>
#include <typedefs.h>
#include <cpu.h>
#include <arch/asm.h>
#include <arch.h>
/** Delay the execution for the given number of microseconds (or slightly more).
*
* The delay is implemented as active delay loop.
*
* @param usec Number of microseconds to sleep.
*/
void delay(uint32_t usec)
{
/*
* The delay loop is calibrated for each and every CPU in the system.
* If running in a thread context, it is therefore necessary to disable
* thread migration. We want to do this in a lightweight manner.
*/
if (THREAD)
thread_migration_disable();
asm_delay_loop(usec * CPU->delay_loop_const);
if (THREAD)
thread_migration_enable();
}
/** @}
*/