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 "quadmath-imp.h"
  17
  18 __float128
  19 nextafterq (__float128 x, __float128 y)
  20 {
  21         int64_t hx,hy,ix,iy;
  22         uint64_t lx,ly;
  23
  24         GET_FLT128_WORDS64(hx,lx,x);
  25         GET_FLT128_WORDS64(hy,ly,y);
  26         ix = hx&0x7fffffffffffffffLL;           /* |x| */
  27         iy = hy&0x7fffffffffffffffLL;           /* |y| */
  28
  29         if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
  30            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
  31            return x+y;
  32         if(x==y) return y;              /* x=y, return y */
  33         if((ix|lx)==0) {                        /* x == 0 */
  34             SET_FLT128_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
  35
  36             /* here we should raise an underflow flag */
  37             return x;
  38         }
  39         if(hx>=0) {                     /* x > 0 */
  40             if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
  41                 if(lx==0) hx--;
  42                 lx--;
  43             } else {                            /* x < y, x += ulp */
  44                 lx++;
  45                 if(lx==0) hx++;
  46             }
  47         } else {                                /* x < 0 */
  48             if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
  49                 if(lx==0) hx--;
  50                 lx--;
  51             } else {                            /* x > y, x += ulp */
  52                 lx++;
  53                 if(lx==0) hx++;
  54             }
  55         }
  56         hy = hx&0x7fff000000000000LL;
  57         if(hy==0x7fff000000000000LL) return x+x;/* overflow  */
  58         if(hy==0) {
  59             /* here we should raise an underflow flag */
  60         }
  61         SET_FLT128_WORDS64(x,hx,lx);
  62         return x;
  63 }