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glibc  2.9
Functions
s_nexttoward.c File Reference
#include "math.h"
#include <math_private.h>
#include <float.h>
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Functions

double __nexttoward (double x, long double y)

Function Documentation

double __nexttoward ( double  x,
long double  y 
)

Definition at line 35 of file s_nexttoward.c.

{
       int32_t hx,ix;
       int64_t hy,iy;
       u_int32_t lx;
       u_int64_t ly;

       EXTRACT_WORDS(hx,lx,x);
       GET_LDOUBLE_WORDS64(hy,ly,y);
       ix = hx&0x7fffffff;         /* |x| */
       iy = hy&0x7fffffffffffffffLL;      /* |y| */

       if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */
          ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))
                                                     /* y is nan */
          return x+y;
       if((long double) x==y) return y;   /* x=y, return y */
       if((ix|lx)==0) {                   /* x == 0 */
           double u;
           INSERT_WORDS(x,(u_int32_t)((hy>>32)&0x80000000),1);/* return +-minsub */
           u = math_opt_barrier (x);
           u = u * u;
           math_force_eval (u);           /* raise underflow flag */
           return x;
       }
       if(hx>=0) {                        /* x > 0 */
           if (hy<0||(ix>>20)>(iy>>48)-0x3c00
              || ((ix>>20)==(iy>>48)-0x3c00
                  && (((((int64_t)hx)<<28)|(lx>>4))>(hy&0x0000ffffffffffffLL)
                     || (((((int64_t)hx)<<28)|(lx>>4))==(hy&0x0000ffffffffffffLL)
                         && (lx&0xf)>(ly>>60))))) {     /* 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||(ix>>20)>(iy>>48)-0x3c00
              || ((ix>>20)==(iy>>48)-0x3c00
                  && (((((int64_t)hx)<<28)|(lx>>4))>(hy&0x0000ffffffffffffLL)
                     || (((((int64_t)hx)<<28)|(lx>>4))==(hy&0x0000ffffffffffffLL)
                         && (lx&0xf)>(ly>>60))))) {     /* 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)
           /* Force conversion to double.  */
           asm ("" : "+m"(x));
         return x;
       }
       if(hy<0x00100000) {
           double u = x*x;                /* underflow */
           math_force_eval (u);           /* raise underflow flag */
       }
       INSERT_WORDS(x,hx,lx);
       return x;
}