lib/libm/src/w_expf.c

   1 /* w_expf.c -- float version of w_exp.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 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: w_expf.c,v 1.7 2007/08/20 16:01:40 drochner Exp $");
  19 #endif
  20
  21 /*
  22  * wrapper expf(x)
  23  */
  24
  25 #include "namespace.h"
  26 #include "math.h"
  27 #include "math_private.h"
  28
  29 #ifdef __weak_alias
  30 __weak_alias(expf, _expf)
  31 #endif
  32
  33 static const float
  34 o_threshold=  8.8721679688e+01,  /* 0x42b17180 */
  35 u_threshold= -1.0397208405e+02;  /* 0xc2cff1b5 */
  36
  37 float
  38 expf(float x)           /* wrapper expf */
  39 {
  40 #ifdef _IEEE_LIBM
  41         return __ieee754_expf(x);
  42 #else
  43         float z;
  44         z = __ieee754_expf(x);
  45         if(_LIB_VERSION == _IEEE_) return z;
  46         if(finitef(x)) {
  47             if(x>o_threshold)
  48                 /* exp overflow */
  49                 return (float)__kernel_standard((double)x,(double)x,106);
  50             else if(x<u_threshold)
  51                 /* exp underflow */
  52                 return (float)__kernel_standard((double)x,(double)x,107);
  53         }
  54         return z;
  55 #endif
  56 }