| /* |
| * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * __ieee754_fmod(x,y) |
| * Return x mod y in exact arithmetic |
| * Method: shift and subtract |
| */ |
| |
| #include "fdlibm.h" |
| |
| #ifdef __STDC__ |
| static const double one = 1.0, Zero[] = {0.0, -0.0,}; |
| #else |
| static double one = 1.0, Zero[] = {0.0, -0.0,}; |
| #endif |
| |
| #ifdef __STDC__ |
| double __ieee754_fmod(double x, double y) |
| #else |
| double __ieee754_fmod(x,y) |
| double x,y ; |
| #endif |
| { |
| int n,hx,hy,hz,ix,iy,sx,i; |
| unsigned lx,ly,lz; |
| |
| hx = __HI(x); /* high word of x */ |
| lx = __LO(x); /* low word of x */ |
| hy = __HI(y); /* high word of y */ |
| ly = __LO(y); /* low word of 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[(unsigned)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[(unsigned)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[(unsigned)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)); |
| __HI(x) = hx|sx; |
| __LO(x) = lx; |
| } else { /* subnormal output */ |
| n = -1022 - iy; |
| if(n<=20) { |
| lx = (lx>>n)|((unsigned)hx<<(32-n)); |
| hx >>= n; |
| } else if (n<=31) { |
| lx = (hx<<(32-n))|(lx>>n); hx = sx; |
| } else { |
| lx = hx>>(n-32); hx = sx; |
| } |
| __HI(x) = hx|sx; |
| __LO(x) = lx; |
| x *= one; /* create necessary signal */ |
| } |
| return x; /* exact output */ |
| } |