blob: 7000600107b7b8bd7798a6c2a43657ba926aa514 [file] [log] [blame]
Andrew Rossignold61f9eb2016-05-27 12:30:37 -07001/* sf_scalbn.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 "fdlibm.h"
17#include <limits.h>
18#include <float.h>
19
20#if INT_MAX > 50000
21#define OVERFLOW_INT 50000
22#else
23#define OVERFLOW_INT 30000
24#endif
25
26#ifdef __STDC__
27static const float
28#else
29static float
30#endif
31two25 = 3.355443200e+07, /* 0x4c000000 */
32twom25 = 2.9802322388e-08, /* 0x33000000 */
33huge = 1.0e+30,
34tiny = 1.0e-30;
35
36#ifdef __STDC__
37 float scalbnf (float x, int n)
38#else
39 float scalbnf (x,n)
40 float x; int n;
41#endif
42{
43 __int32_t k,ix;
44 __uint32_t hx;
45
46 GET_FLOAT_WORD(ix,x);
47 hx = ix&0x7fffffff;
48 k = hx>>23; /* extract exponent */
49 if (FLT_UWORD_IS_ZERO(hx))
50 return x;
51 if (!FLT_UWORD_IS_FINITE(hx))
52 return x+x; /* NaN or Inf */
53 if (FLT_UWORD_IS_SUBNORMAL(hx)) {
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 k = k+n;
60 if (k > FLT_LARGEST_EXP) return huge*copysignf(huge,x); /* overflow */
61 if (k > 0) /* normal result */
62 {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
63 if (k < FLT_SMALLEST_EXP) {
64 if (n > OVERFLOW_INT) /* in case integer overflow in n+k */
65 return huge*copysignf(huge,x); /*overflow*/
66 else return tiny*copysignf(tiny,x); /*underflow*/
67 }
68 k += 25; /* subnormal result */
69 SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
70 return x*twom25;
71}
72
73#ifdef _DOUBLE_IS_32BITS
74
75#ifdef __STDC__
76 double scalbn(double x, int n)
77#else
78 double scalbn(x,n)
79 double x;
80 int n;
81#endif
82{
83 return (double) scalbnf((float) x, n);
84}
85
86#endif /* defined(_DOUBLE_IS_32BITS) */