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lightning-sunbird  0.9+nobinonly
Functions | Variables
e_fmod.c File Reference
#include "fdlibm.h"

Go to the source code of this file.

Functions

double __ieee754_fmod (double x, double y)

Variables

static double one = 1.0
static double Zero [] = {0.0, -0.0,}

Function Documentation

double __ieee754_fmod ( double  x,
double  y 
)

Definition at line 69 of file e_fmod.c.

{
        fd_twoints ux, uy;
       int n,hx,hy,hz,ix,iy,sx,i;
       unsigned lx,ly,lz;

        ux.d = x; uy.d = y;
       hx = __HI(ux);              /* high word of x */
       lx = __LO(ux);              /* low  word of x */
       hy = __HI(uy);              /* high word of y */
       ly = __LO(uy);              /* 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|-(int)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));
            ux.d = x;
           __HI(ux) = hx|sx;
           __LO(ux) = lx;
            x = ux.d;
       } 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;
           }
            ux.d = x;
           __HI(ux) = hx|sx;
           __LO(ux) = lx;
            x = ux.d;
           x *= one;        /* create necessary signal */
       }
       return x;            /* exact output */
}

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Variable Documentation

double one = 1.0 [static]

Definition at line 63 of file e_fmod.c.

double Zero[] = {0.0, -0.0,} [static]

Definition at line 63 of file e_fmod.c.