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