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glibc  2.9
Functions | Variables
e_fmodl.c File Reference
#include "math.h"
#include "math_private.h"

Go to the source code of this file.

Functions

long double __ieee754_fmodl (long double x, long double y)

Variables

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

Function Documentation

long double __ieee754_fmodl ( long double  x,
long double  y 
)

Definition at line 33 of file e_fmodl.c.

{
       int64_t n,hx,hy,hz,ix,iy,sx,i;
       u_int64_t lx,ly,lz;

       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)==0||(hx>=0x7fff000000000000LL)|| /* y=0,or x not finite */
         ((hy|((ly|-ly)>>63))>0x7fff000000000000LL))    /* 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<0x0001000000000000LL) {      /* subnormal x */
           if(hx==0) {
              for (ix = -16431, i=lx; i>0; i<<=1) ix -=1;
           } else {
              for (ix = -16382, i=hx<<15; i>0; i<<=1) ix -=1;
           }
       } else ix = (hx>>48)-0x3fff;

    /* determine iy = ilogb(y) */
       if(hy<0x0001000000000000LL) {      /* subnormal y */
           if(hy==0) {
              for (iy = -16431, i=ly; i>0; i<<=1) iy -=1;
           } else {
              for (iy = -16382, i=hy<<15; i>0; i<<=1) iy -=1;
           }
       } else iy = (hy>>48)-0x3fff;

    /* set up {hx,lx}, {hy,ly} and align y to x */
       if(ix >= -16382) 
           hx = 0x0001000000000000LL|(0x0000ffffffffffffLL&hx);
       else {        /* subnormal x, shift x to normal */
           n = -16382-ix;
           if(n<=63) {
               hx = (hx<<n)|(lx>>(64-n));
               lx <<= n;
           } else {
              hx = lx<<(n-64);
              lx = 0;
           }
       }
       if(iy >= -16382) 
           hy = 0x0001000000000000LL|(0x0000ffffffffffffLL&hy);
       else {        /* subnormal y, shift y to normal */
           n = -16382-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)==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)==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>= -16382) {    /* normalize output */
           hx = ((hx-0x0001000000000000LL)|((iy+16383)<<48));
           SET_LDOUBLE_WORDS64(x,hx|sx,lx);
       } else {             /* subnormal output */
           n = -16382 - 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;
           }
           SET_LDOUBLE_WORDS64(x,hx|sx,lx);
           x *= one;        /* create necessary signal */
       }
       return x;            /* exact output */
}

Variable Documentation

long double one = 1.0 [static]

Definition at line 27 of file e_fmodl.c.

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

Definition at line 27 of file e_fmodl.c.