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/* e_fmodl.c -- long double version of e_fmod.c.
* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
*/
/*
* ====================================================
* 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_fmodl(x,y)
* Return x mod y in exact arithmetic
* Method: shift and subtract
*/
#include "math.h"
#include "math_private.h"
#include <ieee754.h>
#ifdef __STDC__
static const long double one = 1.0, Zero[] = {0.0, -0.0,};
#else
static long double one = 1.0, Zero[] = {0.0, -0.0,};
#endif
#ifdef __STDC__
long double __ieee754_fmodl(long double x, long double y)
#else
long double __ieee754_fmodl(x,y)
long double x,y;
#endif
{
int64_t n,hx,hy,hz,ix,iy,sx,i;
u_int64_t lx,ly,lz;
int temp;
GET_LDOUBLE_WORDS64(hx,lx,x);
GET_LDOUBLE_WORDS64(hy,ly,y);
sx = hx&0x8000000000000000ULL; /* sign of x */
hx ^=sx; /* |x| */
hy &= 0x7fffffffffffffffLL; /* |y| */
/* purge off exception values */
if((hy|(ly&0x7fffffffffffffff))==0||(hx>=0x7ff0000000000000LL)|| /* y=0,or x not finite */
(hy>0x7ff0000000000000LL)) /* 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[(u_int64_t)sx>>63]; /* |x|=|y| return x*0*/
}
/* determine ix = ilogb(x) */
if(hx<0x0010000000000000LL) { /* subnormal x */
if(hx==0) {
for (ix = -1043, i=lx; i>0; i<<=1) ix -=1;
} else {
for (ix = -1022, i=hx<<19; i>0; i<<=1) ix -=1;
}
} else ix = (hx>>52)-0x3ff;
/* determine iy = ilogb(y) */
if(hy<0x0010000000000000LL) { /* subnormal y */
if(hy==0) {
for (iy = -1043, i=ly; i>0; i<<=1) iy -=1;
} else {
for (iy = -1022, i=hy<<19; i>0; i<<=1) iy -=1;
}
} else iy = (hy>>52)-0x3ff;
/* Make the IBM extended format 105 bit mantissa look like the ieee854 112
bit mantissa so the following operatations will give the correct
result. */
ldbl_extract_mantissa(&hx, &lx, &temp, x);
ldbl_extract_mantissa(&hy, &ly, &temp, y);
/* set up {hx,lx}, {hy,ly} and align y to x */
if(ix >= -1022)
hx = 0x0001000000000000LL|(0x0000ffffffffffffLL&hx);
else { /* subnormal x, shift x to normal */
n = -1022-ix;
if(n<=63) {
hx = (hx<<n)|(lx>>(64-n));
lx <<= n;
} else {
hx = lx<<(n-64);
lx = 0;
}
}
if(iy >= -1022)
hy = 0x0001000000000000LL|(0x0000ffffffffffffLL&hy);
else { /* subnormal y, shift y to normal */
n = -1022-iy;
if(n<=63) {
hy = (hy<<n)|(ly>>(64-n));
ly <<= n;
} else {
hy = ly<<(n-64);
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>>63); lx = lx+lx;}
else {
if((hz|(lz&0x7fffffffffffffff))==0) /* return sign(x)*0 */
return Zero[(u_int64_t)sx>>63];
hx = hz+hz+(lz>>63); 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&0x7fffffffffffffff))==0) /* return sign(x)*0 */
return Zero[(u_int64_t)sx>>63];
while(hx<0x0001000000000000LL) { /* normalize x */
hx = hx+hx+(lx>>63); lx = lx+lx;
iy -= 1;
}
if(iy>= -1022) { /* normalize output */
x = ldbl_insert_mantissa((sx>>63), iy, hx, lx);
} else { /* subnormal output */
n = -1022 - iy;
if(n<=48) {
lx = (lx>>n)|((u_int64_t)hx<<(64-n));
hx >>= n;
} else if (n<=63) {
lx = (hx<<(64-n))|(lx>>n); hx = sx;
} else {
lx = hx>>(n-64); hx = sx;
}
x = ldbl_insert_mantissa((sx>>63), iy, hx, lx);
x *= one; /* create necessary signal */
}
return x; /* exact output */
}
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