1 /* s_scalbnf.c -- float version of s_scalbn.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 #ifndef lint
17 static char rcsid[] = "$FreeBSD$";
18 #endif
19 
20 #include <sys/cdefs.h>
21 
22 #include "math.h"
23 #include "math_private.h"
24 
25 static const float
26 two25   =  3.355443200e+07,	/* 0x4c000000 */
27 twom25  =  2.9802322388e-08,	/* 0x33000000 */
28 huge   = 1.0e+30,
29 tiny   = 1.0e-30;
30 
31 float
scalbnf(float x,int n)32 scalbnf (float x, int n)
33 {
34 	int32_t k,ix;
35 	GET_FLOAT_WORD(ix,x);
36         k = (ix&0x7f800000)>>23;		/* extract exponent */
37         if (k==0) {				/* 0 or subnormal x */
38             if ((ix&0x7fffffff)==0) return x; /* +-0 */
39 	    x *= two25;
40 	    GET_FLOAT_WORD(ix,x);
41 	    k = ((ix&0x7f800000)>>23) - 25;
42             if (n< -50000) return tiny*x; 	/*underflow*/
43 	    }
44         if (k==0xff) return x+x;		/* NaN or Inf */
45         k = k+n;
46         if (k >  0xfe) return huge*copysignf(huge,x); /* overflow  */
47         if (k > 0) 				/* normal result */
48 	    {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
49         if (k <= -25)
50             if (n > 50000) 	/* in case integer overflow in n+k */
51 		return huge*copysignf(huge,x);	/*overflow*/
52 	    else return tiny*copysignf(tiny,x);	/*underflow*/
53         k += 25;				/* subnormal result */
54 	SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
55         return x*twom25;
56 }
57 
58 __strong_reference(scalbnf, ldexpf);
59