currtime.c

几个FFT算法

#include <windows.h>
#include "currTime.h"

extern double currTime(); //使用高精度计时器

static LARGE_INTEGER freq;

static BOOL initFreq()
{
	if ( !QueryPerformanceFrequency( &freq) )
		return FALSE;
	else
		return TRUE;
}

double currTime() //使用高精度计时器
{	
	LARGE_INTEGER performanceCount;
	double time;
	BOOL result;
	if (freq.QuadPart==0)
	{
		BOOL bRet=initFreq();
		if (!bRet)
			return 0;
	}
	result=QueryPerformanceCounter(  &performanceCount );
	time= performanceCount.HighPart * 4294967296.0 + performanceCount.LowPart;
	time=time / (   freq.HighPart * 4294967296.0 + freq.LowPart);
	return time;
}