C++程序  |  67行  |  2.12 KB

/*
 * Copyright (C)2011 D. R. Commander.  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.
 * - Neither the name of the libjpeg-turbo Project nor the names of its
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDERS OR CONTRIBUTORS 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.
 */

#ifdef _WIN32

#include <windows.h>

static double getfreq(void)
{
	LARGE_INTEGER freq;
	if(!QueryPerformanceFrequency(&freq)) return 0.0;
	return (double)freq.QuadPart;
}

static double f=-1.0;

double gettime(void)
{
	LARGE_INTEGER t;
	if(f<0.0) f=getfreq();
	if(f==0.0) return (double)GetTickCount()/1000.;
	else
	{
		QueryPerformanceCounter(&t);
		return (double)t.QuadPart/f;
	}
}

#else

#include <stdlib.h>
#include <sys/time.h>

double gettime(void)
{
	struct timeval tv;
	if(gettimeofday(&tv, NULL)<0) return 0.0;
	else return (double)tv.tv_sec+((double)tv.tv_usec/1000000.);
}

#endif