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      1 /* @(#)w_log10.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_log2.c,v 1.2 2024/07/16 14:52:50 riastradh Exp $");
     16 #endif
     17 
     18 /*
     19  * wrapper log2(X)
     20  */
     21 
     22 #include "namespace.h"
     23 
     24 #include "math.h"
     25 #include "math_private.h"
     26 
     27 #ifndef __HAVE_LONG_DOUBLE
     28 __weak_alias(log2l, _log2l)
     29 __strong_alias(_log2l, _log2)
     30 #endif
     31 
     32 __weak_alias(log2, _log2)
     33 double
     34 log2(double x)		/* wrapper log10 */
     35 {
     36 #ifdef _IEEE_LIBM
     37 	return __ieee754_log2(x);
     38 #else
     39 	double z;
     40 	z = __ieee754_log2(x);
     41 	if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
     42 	if(x<=0.0) {
     43 	    if(x==0.0)
     44 	        return __kernel_standard(x,x,48); /* log2(0) */
     45 	    else
     46 	        return __kernel_standard(x,x,49); /* log2(x<0) */
     47 	} else
     48 	    return z;
     49 #endif
     50 }
     51