/* @(#)e_fmod.c 5.1 93/09/24 */ | |
/* | |
* ==================================================== | |
* 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. | |
* ==================================================== | |
*/ | |
#include <LibConfig.h> | |
#include <sys/EfiCdefs.h> | |
#if defined(LIBM_SCCS) && !defined(lint) | |
__RCSID("$NetBSD: e_fmod.c,v 1.11 2002/05/26 22:01:49 wiz Exp $"); | |
#endif | |
/* | |
* __ieee754_fmod(x,y) | |
* Return x mod y in exact arithmetic | |
* Method: shift and subtract | |
*/ | |
#include "math.h" | |
#include "math_private.h" | |
#if defined(_MSC_VER) /* Handle Microsoft VC++ compiler specifics. */ | |
// unary minus operator applied to unsigned type, result still unsigned | |
#pragma warning ( disable : 4146 ) | |
#endif | |
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; | |
u_int32_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[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/ | |
} | |
/* determine ix = ilogb(x) */ | |
if(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(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(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(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[(u_int32_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[(u_int32_t)sx>>31]; | |
while(hx<0x00100000) { /* normalize x */ | |
hx = hx+hx+(lx>>31); lx = lx+lx; | |
iy -= 1; | |
} | |
if(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)|((u_int32_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 */ | |
} |