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