Thread: sqrt()

http://www.nist.gov/dads/HTML/squareRoot.html

asm VC++ sintax

Code:

__declspec(naked) float sqrt(float num){
    __asm{
	FLD dword ptr [esp+4]
	FSQRT
	FIST dword ptr [esp+4]
	mov eax, dword ptr [esp+4]
	ret
    }
}

#include<stdio.h>
int main(){
	float i;
	for(i=0;i<20;i++)
		printf("sqrt of %f is %f\n",i,sqrt(i));
	return 0;

}

Hum. I was having troubles when using 'num' instead of 'dword ptr [esp+4]' because the compiler was translating the num var adress as esp+8..... so I hard typed the adress every time.
EDIT
actually if you debug the app and view the dissassembly, sqrt will call about 40 asm instrutions... don't ask me why...