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      1 /* s_scalbnf.c -- float version of s_scalbn.c.
      2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) 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: s_scalbnf.c,v 1.12 2013/05/20 19:40:09 joerg Exp $");
     19 #endif
     20 
     21 #include "namespace.h"
     22 #include "math.h"
     23 #include "math_private.h"
     24 
     25 #ifndef _LP64
     26 __strong_alias(_scalbnf, _scalblnf)
     27 #endif
     28 __weak_alias(scalbnf, _scalbnf)
     29 __weak_alias(scalblnf, _scalblnf)
     30 __weak_alias(ldexpf, _scalbnf)
     31 
     32 static const float
     33 two25   =  0x1.0p25,	/* 0x4c000000 */
     34 twom25  =  0x1.0p-25,	/* 0x33000000 */
     35 huge   = 1.0e+30,
     36 tiny   = 1.0e-30;
     37 
     38 #ifdef _LP64
     39 float
     40 scalbnf(float x, int n)
     41 {
     42 	return scalblnf(x, n);
     43 }
     44 #endif
     45 
     46 float
     47 scalblnf(float x, long n)
     48 {
     49 	int32_t k,ix;
     50 	GET_FLOAT_WORD(ix,x);
     51         k = (ix&0x7f800000)>>23;		/* extract exponent */
     52         if (k==0) {				/* 0 or subnormal x */
     53             if ((ix&0x7fffffff)==0) return x; /* +-0 */
     54 	    x *= two25;
     55 	    GET_FLOAT_WORD(ix,x);
     56 	    k = ((ix&0x7f800000)>>23) - 25;
     57             if (n< -50000) return tiny*x; 	/*underflow*/
     58 	    }
     59         if (k==0xff) return x+x;		/* NaN or Inf */
     60         k = k+n;
     61         if (k >  0xfe) return huge*copysignf(huge,x); /* overflow  */
     62         if (k > 0) 				/* normal result */
     63 	    {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
     64         if (k <= -25) {
     65             if (n > 50000) 	/* in case integer overflow in n+k */
     66 		return huge*copysignf(huge,x);	/*overflow*/
     67 	    else return tiny*copysignf(tiny,x);	/*underflow*/
     68 	}
     69         k += 25;				/* subnormal result */
     70 	SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
     71         return x*twom25;
     72 }
     73