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             float u;
  44             SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
  45             u = math_opt_barrier (x);
  46             u = u*u;
  47             math_force_eval (u);                /* raise underflow flag */
  48             return x;
  49         }
  50         if(hx>=0) {                             /* x > 0 */
  51             if(hx>hy) {                         /* x > y, x -= ulp */
  52                 hx -= 1;
  53             } else {                            /* x < y, x += ulp */
  54                 hx += 1;
  55             }
  56         } else {                                /* x < 0 */
  57             if(hy>=0||hx>hy){                   /* x < y, x -= ulp */
  58                 hx -= 1;
  59             } else {                            /* x > y, x += ulp */
  60                 hx += 1;
  61             }
  62         }
  63         hy = hx&0x7f800000;
  64         if(hy>=0x7f800000) {
  65           x = x+x;      /* overflow  */
  66           if (FLT_EVAL_METHOD != 0)
  67             asm ("" : "+m"(x));
  68           return x;     /* overflow  */
  69         }
  70         if(hy<0x00800000) {
  71             float u = x*x;                      /* underflow */
  72             math_force_eval (u);                /* raise underflow flag */
  73         }
  74         SET_FLOAT_WORD(x,hx);
  75         return x;
  76 }
  77 weak_alias (__nextafterf, nextafterf)