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 #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
scalbnf(float x,int n)40 scalbnf(float x, int n)
41 {
42 return scalblnf(x, n);
43 }
44 #endif
45
46 float
scalblnf(float x,long n)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