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/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* __ieee754_fmod(x,y)
* Return x mod y in exact arithmetic
* Method: shift and subtract
*/
#include <math.h>
#include <math_private.h>
#include <libm-alias-finite.h>
static const double one = 1.0, Zero[] = { 0.0, -0.0, };
double
__ieee754_fmod (double x, double y)
{
int32_t n, hx, hy, hz, ix, iy, sx, i;
uint32_t lx, ly, lz;
EXTRACT_WORDS (hx, lx, x);
EXTRACT_WORDS (hy, ly, y);
sx = hx & 0x80000000; /* sign of x */
hx ^= sx; /* |x| */
hy &= 0x7fffffff; /* |y| */
/* purge off exception values */
if ((hy | ly) == 0 || (hx >= 0x7ff00000) || /* y=0,or x not finite */
((hy | ((ly | -ly) >> 31)) > 0x7ff00000)) /* or y is NaN */
return (x * y) / (x * y);
if (hx <= hy)
{
if ((hx < hy) || (lx < ly))
return x; /* |x|<|y| return x */
if (lx == ly)
return Zero[(uint32_t) sx >> 31]; /* |x|=|y| return x*0*/
}
/* determine ix = ilogb(x) */
if (__glibc_unlikely (hx < 0x00100000)) /* subnormal x */
{
if (hx == 0)
{
for (ix = -1043, i = lx; i > 0; i <<= 1)
ix -= 1;
}
else
{
for (ix = -1022, i = (hx << 11); i > 0; i <<= 1)
ix -= 1;
}
}
else
ix = (hx >> 20) - 1023;
/* determine iy = ilogb(y) */
if (__glibc_unlikely (hy < 0x00100000)) /* subnormal y */
{
if (hy == 0)
{
for (iy = -1043, i = ly; i > 0; i <<= 1)
iy -= 1;
}
else
{
for (iy = -1022, i = (hy << 11); i > 0; i <<= 1)
iy -= 1;
}
}
else
iy = (hy >> 20) - 1023;
/* set up {hx,lx}, {hy,ly} and align y to x */
if (__glibc_likely (ix >= -1022))
hx = 0x00100000 | (0x000fffff & hx);
else /* subnormal x, shift x to normal */
{
n = -1022 - ix;
if (n <= 31)
{
hx = (hx << n) | (lx >> (32 - n));
lx <<= n;
}
else
{
hx = lx << (n - 32);
lx = 0;
}
}
if (__glibc_likely (iy >= -1022))
hy = 0x00100000 | (0x000fffff & hy);
else /* subnormal y, shift y to normal */
{
n = -1022 - iy;
if (n <= 31)
{
hy = (hy << n) | (ly >> (32 - n));
ly <<= n;
}
else
{
hy = ly << (n - 32);
ly = 0;
}
}
/* fix point fmod */
n = ix - iy;
while (n--)
{
hz = hx - hy; lz = lx - ly; if (lx < ly)
hz -= 1;
if (hz < 0)
{
hx = hx + hx + (lx >> 31); lx = lx + lx;
}
else
{
if ((hz | lz) == 0) /* return sign(x)*0 */
return Zero[(uint32_t) sx >> 31];
hx = hz + hz + (lz >> 31); lx = lz + lz;
}
}
hz = hx - hy; lz = lx - ly; if (lx < ly)
hz -= 1;
if (hz >= 0)
{
hx = hz; lx = lz;
}
/* convert back to floating value and restore the sign */
if ((hx | lx) == 0) /* return sign(x)*0 */
return Zero[(uint32_t) sx >> 31];
while (hx < 0x00100000) /* normalize x */
{
hx = hx + hx + (lx >> 31); lx = lx + lx;
iy -= 1;
}
if (__glibc_likely (iy >= -1022)) /* normalize output */
{
hx = ((hx - 0x00100000) | ((iy + 1023) << 20));
INSERT_WORDS (x, hx | sx, lx);
}
else /* subnormal output */
{
n = -1022 - iy;
if (n <= 20)
{
lx = (lx >> n) | ((uint32_t) hx << (32 - n));
hx >>= n;
}
else if (n <= 31)
{
lx = (hx << (32 - n)) | (lx >> n); hx = sx;
}
else
{
lx = hx >> (n - 32); hx = sx;
}
INSERT_WORDS (x, hx | sx, lx);
x *= one; /* create necessary signal */
}
return x; /* exact output */
}
libm_alias_finite (__ieee754_fmod, __fmod)
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