lib/msun/src/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  * $FreeBSD: src/lib/msun/src/s_nextafterf.c,v 1.5 1999/08/28 00:06:54 peter Exp $
   5  * $DragonFly: src/lib/msun/src/Attic/s_nextafterf.c,v 1.2 2003/06/17 04:26:53 dillon Exp $
   6  */
   7
   8 /*
   9  * ====================================================
  10  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  11  *
  12  * Developed at SunPro, a Sun Microsystems, Inc. business.
  13  * Permission to use, copy, modify, and distribute this
  14  * software is freely granted, provided that this notice
  15  * is preserved.
  16  * ====================================================
  17  */
  18
  19 #include "math.h"
  20 #include "math_private.h"
  21
  22 #ifdef __STDC__
  23         float nextafterf(float x, float y)
  24 #else
  25         float nextafterf(x,y)
  26         float x,y;
  27 #endif
  28 {
  29         int32_t hx,hy,ix,iy;
  30
  31         GET_FLOAT_WORD(hx,x);
  32         GET_FLOAT_WORD(hy,y);
  33         ix = hx&0x7fffffff;             /* |x| */
  34         iy = hy&0x7fffffff;             /* |y| */
  35
  36         if((ix>0x7f800000) ||   /* x is nan */
  37            (iy>0x7f800000))     /* y is nan */
  38            return x+y;
  39         if(x==y) return x;              /* x=y, return x */
  40         if(ix==0) {                             /* x == 0 */
  41             SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
  42             y = x*x;
  43             if(y==x) return y; else return x;   /* raise underflow flag */
  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) return x+x;  /* overflow  */
  60         if(hy<0x00800000) {             /* underflow */
  61             y = x*x;
  62             if(y!=x) {          /* raise underflow flag */
  63                 SET_FLOAT_WORD(y,hx);
  64                 return y;
  65             }
  66         }
  67         SET_FLOAT_WORD(x,hx);
  68         return x;
  69 }