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

Go to the source code of this file.

Functions

float __ieee754_fmodf (float x, float y)

Variables

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

Function Documentation

float __ieee754_fmodf ( float  x,
float  y 
)

Definition at line 38 of file e_fmodf.c.

{
       int32_t n,hx,hy,hz,ix,iy,sx,i;

       GET_FLOAT_WORD(hx,x);
       GET_FLOAT_WORD(hy,y);
       sx = hx&0x80000000;         /* sign of x */
       hx ^=sx;             /* |x| */
       hy &= 0x7fffffff;    /* |y| */

    /* purge off exception values */
       if(hy==0||(hx>=0x7f800000)||              /* y=0,or x not finite */
          (hy>0x7f800000))                /* or y is NaN */
           return (x*y)/(x*y);
       if(hx<hy) return x;                /* |x|<|y| return x */
       if(hx==hy)
           return Zero[(u_int32_t)sx>>31];       /* |x|=|y| return x*0*/

    /* determine ix = ilogb(x) */
       if(hx<0x00800000) {  /* subnormal x */
           for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
       } else ix = (hx>>23)-127;

    /* determine iy = ilogb(y) */
       if(hy<0x00800000) {  /* subnormal y */
           for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
       } else iy = (hy>>23)-127;

    /* set up {hx,lx}, {hy,ly} and align y to x */
       if(ix >= -126) 
           hx = 0x00800000|(0x007fffff&hx);
       else {        /* subnormal x, shift x to normal */
           n = -126-ix;
           hx = hx<<n;
       }
       if(iy >= -126) 
           hy = 0x00800000|(0x007fffff&hy);
       else {        /* subnormal y, shift y to normal */
           n = -126-iy;
           hy = hy<<n;
       }

    /* fix point fmod */
       n = ix - iy;
       while(n--) {
           hz=hx-hy;
           if(hz<0){hx = hx+hx;}
           else {
              if(hz==0)            /* return sign(x)*0 */
                  return Zero[(u_int32_t)sx>>31];
              hx = hz+hz;
           }
       }
       hz=hx-hy;
       if(hz>=0) {hx=hz;}

    /* convert back to floating value and restore the sign */
       if(hx==0)                   /* return sign(x)*0 */
           return Zero[(u_int32_t)sx>>31];       
       while(hx<0x00800000) {             /* normalize x */
           hx = hx+hx;
           iy -= 1;
       }
       if(iy>= -126) {             /* normalize output */
           hx = ((hx-0x00800000)|((iy+127)<<23));
           SET_FLOAT_WORD(x,hx|sx);
       } else {             /* subnormal output */
           n = -126 - iy;
           hx >>= n;
           SET_FLOAT_WORD(x,hx|sx);
           x *= one;        /* create necessary signal */
       }
       return x;            /* exact output */
}

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Variable Documentation

float one = 1.0 [static]

Definition at line 32 of file e_fmodf.c.

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

Definition at line 32 of file e_fmodf.c.