usleep.c

基于Xilinx-XUPV2P开发平台的嵌入式系统实验例程：实验4编写基本的应用程序

/*-----------------------------------------------------------------------------
//     $Date: 2005/06/30 22:22:14 $
//     $RCSfile: usleep.c,v $
//-----------------------------------------------------------------------------
//
// Copyright (c) 2004 Xilinx, Inc.  All rights reserved. 
// 
// Xilinx, Inc. 
// XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS" AS A 
// COURTESY TO YOU.  BY PROVIDING THIS DESIGN, CODE, OR INFORMATION AS 
// ONE POSSIBLE   IMPLEMENTATION OF THIS FEATURE, APPLICATION OR 
// STANDARD, XILINX IS MAKING NO REPRESENTATION THAT THIS IMPLEMENTATION 
// IS FREE FROM ANY CLAIMS OF INFRINGEMENT, AND YOU ARE RESPONSIBLE 
// FOR OBTAINING ANY RIGHTS YOU MAY REQUIRE FOR YOUR IMPLEMENTATION. 
// XILINX EXPRESSLY DISCLAIMS ANY WARRANTY WHATSOEVER WITH RESPECT TO 
// THE ADEQUACY OF THE IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO 
// ANY WARRANTIES OR REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE 
// FROM CLAIMS OF INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY 
// AND FITNESS FOR A PARTICULAR PURPOSE.
//
//---------------------------------------------------------------------------*/

#include "sleep.h"
#include "xtime_l.h"
#include "xparameters.h"

void nanosleep(unsigned int nanoseconds)
{
  /* not implemented */
}

void usleep(unsigned int useconds)
{
  XTime tEnd, tCur;

  XTime_GetTime(&tCur);
  tEnd = tCur + ((XTime) useconds) * (XPAR_CPU_PPC405_CORE_CLOCK_FREQ_HZ / 1000000);
  do
  {
    XTime_GetTime(&tCur);
  } while (tCur < tEnd);
}