sysdeps/ieee754/flt-32/s_nextafterf.c

   1 /* s_nextafterf.c -- float version of s_nextafter.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   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 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: s_nextafterf.c,v 1.4 1995/05/10 20:48:01 jtc Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #include "math_private.h"
  22 #include <float.h>
  23
  24 #ifdef __STDC__
  25         float __nextafterf(float x, float y)
  26 #else
  27         float __nextafterf(x,y)
  28         float x,y;
  29 #endif
  30 {
  31         int32_t hx,hy,ix,iy;
  32
  33         GET_FLOAT_WORD(hx,x);
  34         GET_FLOAT_WORD(hy,y);
  35         ix = hx&0x7fffffff;             /* |x| */
  36         iy = hy&0x7fffffff;             /* |y| */
  37
  38         if((ix>0x7f800000) ||   /* x is nan */
  39            (iy>0x7f800000))     /* y is nan */
  40            return x+y;
  41         if(x==y) return y;              /* x=y, return y */
  42         if(ix==0) {                             /* x == 0 */
  43             SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
  44             y = x*x;
  45             if(y==x) return y; else return x;   /* raise underflow flag */
  46         }
  47         if(hx>=0) {                             /* x > 0 */
  48             if(hx>hy) {                         /* x > y, x -= ulp */
  49                 hx -= 1;
  50             } else {                            /* x < y, x += ulp */
  51                 hx += 1;
  52             }
  53         } else {                                /* x < 0 */
  54             if(hy>=0||hx>hy){                   /* x < y, x -= ulp */
  55                 hx -= 1;
  56             } else {                            /* x > y, x += ulp */
  57                 hx += 1;
  58             }
  59         }
  60         hy = hx&0x7f800000;
  61         if(hy>=0x7f800000) {
  62           x = x+x;      /* overflow  */
  63           if (FLT_EVAL_METHOD != 0)
  64             asm ("" : "=m"(x) : "m"(x));
  65           return x;     /* overflow  */
  66         }
  67         if(hy<0x00800000) {             /* underflow */
  68             y = x*x;
  69             if(y!=x) {          /* raise underflow flag */
  70                 SET_FLOAT_WORD(y,hx);
  71                 return y;
  72             }
  73         }
  74         SET_FLOAT_WORD(x,hx);
  75         return x;
  76 }
  77 weak_alias (__nextafterf, nextafterf)