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
   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 #ifndef lint
  17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_nextafterf.c,v 1.5 1999/08/28 00:06:54 peter Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #include "math_private.h"
  22
  23 #ifdef __STDC__
  24         float nextafterf(float x, float y)
  25 #else
  26         float nextafterf(x,y)
  27         float x,y;
  28 #endif
  29 {
  30         int32_t hx,hy,ix,iy;
  31
  32         GET_FLOAT_WORD(hx,x);
  33         GET_FLOAT_WORD(hy,y);
  34         ix = hx&0x7fffffff;             /* |x| */
  35         iy = hy&0x7fffffff;             /* |y| */
  36
  37         if((ix>0x7f800000) ||   /* x is nan */
  38            (iy>0x7f800000))     /* y is nan */
  39            return x+y;
  40         if(x==y) return x;              /* x=y, return x */
  41         if(ix==0) {                             /* x == 0 */
  42             SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
  43             y = x*x;
  44             if(y==x) return y; else return x;   /* raise underflow flag */
  45         }
  46         if(hx>=0) {                             /* x > 0 */
  47             if(hx>hy) {                         /* x > y, x -= ulp */
  48                 hx -= 1;
  49             } else {                            /* x < y, x += ulp */
  50                 hx += 1;
  51             }
  52         } else {                                /* x < 0 */
  53             if(hy>=0||hx>hy){                   /* x < y, x -= ulp */
  54                 hx -= 1;
  55             } else {                            /* x > y, x += ulp */
  56                 hx += 1;
  57             }
  58         }
  59         hy = hx&0x7f800000;
  60         if(hy>=0x7f800000) return x+x;  /* overflow  */
  61         if(hy<0x00800000) {             /* underflow */
  62             y = x*x;
  63             if(y!=x) {          /* raise underflow flag */
  64                 SET_FLOAT_WORD(y,hx);
  65                 return y;
  66             }
  67         }
  68         SET_FLOAT_WORD(x,hx);
  69         return x;
  70 }