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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup time
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Active delay function.
  36.  */
  37.  
  38. #include <time/delay.h>
  39. #include <arch/types.h>
  40. #include <cpu.h>
  41. #include <arch/asm.h>
  42. #include <arch.h>
  43.  
  44. /** Active delay
  45.  *
  46.  * Delay the execution for the given number
  47.  * of microseconds (or slightly more). The delay
  48.  * is implemented as CPU calibrated active loop.
  49.  *
  50.  * @param usec Number of microseconds to sleep.
  51.  */
  52. void delay(__u32 usec)
  53. {
  54.     ipl_t ipl;
  55.    
  56.     /*
  57.      * The delay loop is calibrated for each and every
  58.      * CPU in the system. Therefore it is necessary to
  59.      * call interrupts_disable() before calling the
  60.      * asm_delay_loop().
  61.      */
  62.     ipl = interrupts_disable();
  63.     asm_delay_loop(usec * CPU->delay_loop_const);
  64.     interrupts_restore(ipl);
  65. }
  66.  
  67. /** @}
  68.  */
  69.  
  70.