StdLib/LibC/Math/w_exp.c

   1 /* @(#)w_exp.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12 #include  <LibConfig.h>
  13 #include  <sys/EfiCdefs.h>
  14 #if defined(LIBM_SCCS) && !defined(lint)
  15 __RCSID("$NetBSD: w_exp.c,v 1.9 2002/05/26 22:02:00 wiz Exp $");
  16 #endif
  17
  18 /*
  19  * wrapper exp(x)
  20  */
  21
  22 #include "math.h"
  23 #include "math_private.h"
  24
  25 #ifndef _IEEE_LIBM
  26 static const double
  27 o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
  28 u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
  29 #endif
  30
  31 double
  32 exp(double x)   /* wrapper exp */
  33 {
  34 #ifdef _IEEE_LIBM
  35   return __ieee754_exp(x);
  36 #else
  37   double z;
  38   z = __ieee754_exp(x);
  39   if(_LIB_VERSION == _IEEE_) return z;
  40   if(finite(x)) {
  41       if(x>o_threshold)
  42           return __kernel_standard(x,x,6); /* exp overflow */
  43       else if(x<u_threshold)
  44           return __kernel_standard(x,x,7); /* exp underflow */
  45   }
  46   return z;
  47 #endif
  48 }