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 #include <sys/cdefs.h>
  17 __FBSDID("$FreeBSD$");
  18
  19 #include "math.h"
  20 #include "math_private.h"
  21
  22 float
  23 nextafterf(float x, float y)
  24 {
  25         volatile float t;
  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             SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
  39             t = x*x;
  40             if(t==x) return t; else return x;   /* raise underflow flag */
  41         }
  42         if(hx>=0) {                             /* x > 0 */
  43             if(hx>hy) {                         /* x > y, x -= ulp */
  44                 hx -= 1;
  45             } else {                            /* x < y, x += ulp */
  46                 hx += 1;
  47             }
  48         } else {                                /* x < 0 */
  49             if(hy>=0||hx>hy){                   /* x < y, x -= ulp */
  50                 hx -= 1;
  51             } else {                            /* x > y, x += ulp */
  52                 hx += 1;
  53             }
  54         }
  55         hy = hx&0x7f800000;
  56         if(hy>=0x7f800000) return x+x;  /* overflow  */
  57         if(hy<0x00800000) {             /* underflow */
  58             t = x*x;
  59             if(t!=x) {          /* raise underflow flag */
  60                 SET_FLOAT_WORD(y,hx);
  61                 return y;
  62             }
  63         }
  64         SET_FLOAT_WORD(x,hx);
  65         return x;
  66 }