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 float __nextafterf(float x, float y)
  25 {
  26         int32_t hx,hy,ix,iy;
  27
  28         GET_FLOAT_WORD(hx,x);
  29         GET_FLOAT_WORD(hy,y);
  30         ix = hx&0x7fffffff;             /* |x| */
  31         iy = hy&0x7fffffff;             /* |y| */
  32
  33         if((ix>0x7f800000) ||   /* x is nan */
  34            (iy>0x7f800000))     /* y is nan */
  35            return x+y;
  36         if(x==y) return y;              /* x=y, return y */
  37         if(ix==0) {                             /* x == 0 */
  38             float u;
  39             SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
  40             u = math_opt_barrier (x);
  41             u = u*u;
  42             math_force_eval (u);                /* raise underflow flag */
  43             return x;
  44         }
  45         if(hx>=0) {                             /* x > 0 */
  46             if(hx>hy) {                         /* x > y, x -= ulp */
  47                 hx -= 1;
  48             } else {                            /* x < y, x += ulp */
  49                 hx += 1;
  50             }
  51         } else {                                /* x < 0 */
  52             if(hy>=0||hx>hy){                   /* x < y, x -= ulp */
  53                 hx -= 1;
  54             } else {                            /* x > y, x += ulp */
  55                 hx += 1;
  56             }
  57         }
  58         hy = hx&0x7f800000;
  59         if(hy>=0x7f800000) {
  60           float u = x+x;        /* overflow  */
  61           math_force_eval (u);
  62         }
  63         if(hy<0x00800000) {
  64             float u = x*x;                      /* underflow */
  65             math_force_eval (u);                /* raise underflow flag */
  66         }
  67         SET_FLOAT_WORD(x,hx);
  68         return x;
  69 }
  70 weak_alias (__nextafterf, nextafterf)