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