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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"
- 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 */
- }
- /*
- * wrapper fmod(x,y)
- */
- #ifndef _IEEE_LIBM
- double fmod(double x, double y)
- {
- double z = __ieee754_fmod(x, y);
- if (_LIB_VERSION == _IEEE_ || isnan(y) || isnan(x))
- return z;
- if (y == 0.0)
- return __kernel_standard(x, y, 27); /* fmod(x,0) */
- return z;
- }
- #else
- strong_alias(__ieee754_fmod, fmod)
- #endif
- libm_hidden_def(fmod)
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