src/base/math/fmod.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

#include <u.h>
#include <base.h>

/*
 * floating-point mod function without infinity or NaN checking
 */
double
math·fmod(double x, double y)
{
	int sign, yexp, rexp;
	double r, yfr, rfr;

	if (y == 0)
		return x;
	if (y < 0)
		y = -y;
	yfr = math·frexp(y, &yexp);
	sign = 0;
	if(x < 0) {
		r = -x;
		sign++;
	} else
		r = x;
	while(r >= y) {
		rfr = math·frexp(r, &rexp);
		r -= math·ldexp(y, rexp - yexp - (rfr < yfr));
	}
	if(sign)
		r = -r;
	return r;
}