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glibc  2.9
Defines | Functions
s_nextafter.c File Reference
#include <math.h>
#include <math_private.h>
#include <float.h>
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Go to the source code of this file.

Defines

#define __nexttoward   __internal___nexttoward
#define nexttoward   __internal_nexttoward

Functions

double __nextafter (double x, double y)

Define Documentation

#define __nexttoward   __internal___nexttoward

Definition at line 25 of file s_nextafter.c.

#define nexttoward   __internal_nexttoward

Definition at line 26 of file s_nextafter.c.


Function Documentation

double __nextafter ( double  x,
double  y 
)

Definition at line 35 of file s_nextafter.c.

{
       int32_t hx,hy,ix,iy;
       u_int32_t lx,ly;

       EXTRACT_WORDS(hx,lx,x);
       EXTRACT_WORDS(hy,ly,y);
       ix = hx&0x7fffffff;         /* |x| */
       iy = hy&0x7fffffff;         /* |y| */

       if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */
          ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))     /* y is nan */
          return x+y;
       if(x==y) return y;          /* x=y, return y */
       if((ix|lx)==0) {                   /* x == 0 */
           double u;
           INSERT_WORDS(x,hy&0x80000000,1);      /* return +-minsubnormal */
           u = math_opt_barrier (x);
           u = u*u;
           math_force_eval (u);           /* raise underflow flag */
           return x;
       }
       if(hx>=0) {                        /* x > 0 */
           if(hx>hy||((hx==hy)&&(lx>ly))) {      /* x > y, x -= ulp */
              if(lx==0) hx -= 1;
              lx -= 1;
           } else {                       /* x < y, x += ulp */
              lx += 1;
              if(lx==0) hx += 1;
           }
       } else {                           /* x < 0 */
           if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
              if(lx==0) hx -= 1;
              lx -= 1;
           } else {                       /* x > y, x += ulp */
              lx += 1;
              if(lx==0) hx += 1;
           }
       }
       hy = hx&0x7ff00000;
       if(hy>=0x7ff00000) {
         x = x+x;    /* overflow  */
         if (FLT_EVAL_METHOD != 0 && FLT_EVAL_METHOD != 1)
           asm ("" : "+m"(x));
         return x;   /* overflow  */
       }
       if(hy<0x00100000) {
           double u = x*x;                /* underflow */
           math_force_eval (u);           /* raise underflow flag */
       }
       INSERT_WORDS(x,hx,lx);
       return x;
}

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