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      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 
     13 #include <sys/cdefs.h>
     14 #if defined(LIBM_SCCS) && !defined(lint)
     15 __RCSID("$NetBSD: w_exp.c,v 1.11 2025/08/24 21:37:31 nat Exp $");
     16 #endif
     17 
     18 /*
     19  * wrapper exp(x)
     20  */
     21 
     22 #include "namespace.h"
     23 #include "math.h"
     24 #include "math_private.h"
     25 
     26 #ifdef __weak_alias
     27 __weak_alias(exp, _exp)
     28 #endif
     29 
     30 #ifndef _IEEE_LIBM
     31 static const double
     32 o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
     33 u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
     34 #endif
     35 
     36 double
     37 exp(double x)		/* wrapper exp */
     38 {
     39 #ifdef _IEEE_LIBM
     40 	return __ieee754_exp(x);
     41 #else
     42 	double z;
     43 	z = __ieee754_exp(x);
     44 	if(_LIB_VERSION == _IEEE_) return z;
     45 	if(finite(x)) {
     46 	    if(x>o_threshold)
     47 	        return __kernel_standard(x,x,6); /* exp overflow */
     48 	    else if(x<u_threshold)
     49 	        return __kernel_standard(x,x,7); /* exp underflow */
     50 	}
     51 	return z;
     52 #endif
     53 }
     54