/* * 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(); } /** @} */