libquadmath/math/nextafterq.c

   1 /* nextafterq.c -- __float128 version of s_nextafter.c.
   2  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #include <errno.h>
  17 #include "quadmath-imp.h"
  18
  19 __float128
  20 nextafterq (__float128 x, __float128 y)
  21 {
  22         int64_t hx,hy,ix,iy;
  23         uint64_t lx,ly;
  24
  25         GET_FLT128_WORDS64(hx,lx,x);
  26         GET_FLT128_WORDS64(hy,ly,y);
  27         ix = hx&0x7fffffffffffffffLL;           /* |x| */
  28         iy = hy&0x7fffffffffffffffLL;           /* |y| */
  29
  30         if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
  31            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
  32            return x+y;
  33         if(x==y) return y;              /* x=y, return y */
  34         if((ix|lx)==0) {                        /* x == 0 */
  35             SET_FLT128_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
  36
  37             /* here we should raise an underflow flag */
  38             return x;
  39         }
  40         if(hx>=0) {                     /* x > 0 */
  41             if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
  42                 if(lx==0) hx--;
  43                 lx--;
  44             } else {                            /* x < y, x += ulp */
  45                 lx++;
  46                 if(lx==0) hx++;
  47             }
  48         } else {                                /* x < 0 */
  49             if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
  50                 if(lx==0) hx--;
  51                 lx--;
  52             } else {                            /* x > y, x += ulp */
  53                 lx++;
  54                 if(lx==0) hx++;
  55             }
  56         }
  57         hy = hx&0x7fff000000000000LL;
  58         if(hy==0x7fff000000000000LL) {
  59             __float128 u = x + x;               /* overflow  */
  60             math_force_eval (u);
  61             errno = ERANGE;
  62         }
  63         if(hy==0) {
  64             __float128 u = x*x;                 /* underflow */
  65             math_force_eval (u);                /* raise underflow flag */
  66             errno = ERANGE;
  67         }
  68         SET_FLT128_WORDS64(x,hx,lx);
  69         return x;
  70 }