jehanne/sys/src/lib/jehanne/port/fmod.c

41 lines
882 B
C

/*
* This file is part of the UCB release of Plan 9. It is subject to the license
* terms in the LICENSE file found in the top-level directory of this
* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
* part of the UCB release of Plan 9, including this file, may be copied,
* modified, propagated, or distributed except according to the terms contained
* in the LICENSE file.
*/
#include <u.h>
#include <libc.h>
/*
* floating-point mod function without infinity or NaN checking
*/
double
jehanne_fmod(double x, double y)
{
int sign, yexp, rexp;
double r, yfr, rfr;
if (y == 0)
return x;
if (y < 0)
y = -y;
yfr = jehanne_frexp(y, &yexp);
sign = 0;
if(x < 0) {
r = -x;
sign++;
} else
r = x;
while(r >= y) {
rfr = jehanne_frexp(r, &rexp);
r -= jehanne_ldexp(y, rexp - yexp - (rfr < yfr));
}
if(sign)
r = -r;
return r;
}