c32_asm.cpp

这是我本人编写的一个32位定点小数运算的函数库。对于没有浮点运算器的场合

// C32_ASM.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <math.h>

extern "C" {

long dosFIX_MPY32(long x,long y);
long dosFIX_MPY32_C(long x,long y);

long VectorMul32(const long v1[],const long v2[],long n);
long VectorMul32_C(const long v1[],const long v2[],long n);

long FixLog32(long x,long e);
long FixLog32_C(long x,long e);

long FixSqrt32(long x,long y);
long FixSqrt32_C(long x,long y);

};

/*
int main()
{
	char buf[8];
	double m=0;
	for (int k=0;k<1000;k++) {
		for (int i=0;i<8;i++)
			buf[i]=(char)rand();

		long x=*(long*)buf,y=*(long*)(buf+4);
		long xy=dosFIX_MPY32_C(x,y);

		double fxy=(double)x*((double)y/0x80000000u);
		double d=fabs(fxy-xy); if (d>m) m=d;
		if (d>1)
			printf("%d\t",k);
	}
	printf("\n");
	printf("Max Delta=%lf\n",m);
	//printf("x=%ld\ty=%ld\nxy=%ld\tfxy=%lf\tdelta=%lf%%\n",x,y,xy,fxy,(xy-fxy)/fxy*100);
	getch(); return 0;
}
*/
/*
#define N 60
int main()
{
	char buf[8];
	double m=0;
	for (int k=0;k<1000;k++) {
		long x[N],y[N];
		for (int l=0;l<N;l++) {
			for (int i=0;i<8;i++)
				buf[i]=(char)rand();

			buf[3]=(buf[3]<0)?-1:0;
			x[l]=*(long*)buf; y[l]=*(long*)(buf+4);
		}
		long xy=VectorMul32_C(x,y,N);
		double fxy=0; for (l=0;l<N;l++) fxy+=(double)x[l]*((double)y[l]/0x80000000u);

		double d=fabs(fxy-xy); if (d>m) m=d;
		if (d>N)
			printf("%d\t",k);
	}
	printf("\n");
	printf("Max Delta=%lf\n",m);
	getch(); return 0;
}
*/
/*
int main()
{
	char buf[4];
	double m=0;
	for (int k=0;k<1000;k++) {
		for (int i=0;i<4;i++)
			buf[i]=(char)rand();

		if (buf[3]<0) buf[3]=-buf[3];
		long x=*(long*)buf,e=rand()*52/RAND_MAX-10;
		long lx0=FixLog32(x,e),lx=FixLog32_C(x,e);

		double flx=log((double)x/pow(2,e));

		double d=fabs(flx*(1<<26)-(double)lx); if (d>m) m=d;
		if (d>100)
			printf("%d\t",k);
	}
	printf("\n");
	printf("Max Delta=%lf\n",m);
	//printf("x=%ld\ty=%ld\nxy=%ld\tfxy=%lf\tdelta=%lf%%\n",x,y,xy,fxy,(xy-fxy)/fxy*100);
	getch(); return 0;
}
*/

int main()
{
	char buf[8];
	double m=0;
	for (int k=0;k<100000;k++) {
		for (int i=0;i<8;i++)
			buf[i]=(char)rand();

		long x=*(long*)buf,y=*(long*)(buf+4);
		x/=2; y/=2;

		long xy=FixSqrt32_C(x,y);

		double fxy=sqrt((double)x*x+(double)y*y);
		double d=fabs(fxy-xy); if (d>m) m=d;
		if (d>1000)
			printf("%d\t",k);
	}
	printf("\n");
	printf("Max Delta=%lf\n",m);
	//printf("x=%ld\ty=%ld\nxy=%ld\tfxy=%lf\tdelta=%lf%%\n",x,y,xy,fxy,(xy-fxy)/fxy*100);
	getch(); return 0;
}