32x: drc: first implementation finished, no more interpreter dep
[picodrive.git] / platform / gp2x / code940 / uClibc / s_scalbn.c
CommitLineData
cc68a136 1/* @(#)s_scalbn.c 5.1 93/09/24 */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13#if defined(LIBM_SCCS) && !defined(lint)
14static char rcsid[] = "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
15#endif
16
17/*
18 * scalbn (double x, int n)
19 * scalbn(x,n) returns x* 2**n computed by exponent
20 * manipulation rather than by actually performing an
21 * exponentiation or a multiplication.
22 */
23
24#include "math.h"
25#include "math_private.h"
26
27#ifdef __STDC__
28static const double
29#else
30static double
31#endif
32two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
33twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
34huge = 1.0e+300,
35tiny = 1.0e-300;
36
37#ifdef __STDC__
38 double scalbn (double x, int n)
39#else
40 double scalbn (x,n)
41 double x; int n;
42#endif
43{
44 int32_t k,hx,lx;
45 EXTRACT_WORDS(hx,lx,x);
46 k = (hx&0x7ff00000)>>20; /* extract exponent */
47 if (k==0) { /* 0 or subnormal x */
48 if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
49 x *= two54;
50 GET_HIGH_WORD(hx,x);
51 k = ((hx&0x7ff00000)>>20) - 54;
52 if (n< -50000) return tiny*x; /*underflow*/
53 }
54 if (k==0x7ff) return x+x; /* NaN or Inf */
55 k = k+n;
56 if (k > 0x7fe) return huge*copysign(huge,x); /* overflow */
57 if (k > 0) /* normal result */
58 {SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
59 if (k <= -54) {
60 if (n > 50000) /* in case integer overflow in n+k */
61 return huge*copysign(huge,x); /*overflow*/
62 else return tiny*copysign(tiny,x); /*underflow*/
63 }
64 k += 54; /* subnormal result */
65 SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
66 return x*twom54;
67}