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 <math.h>
17#include <math_private.h>
18
19static const float
20two25 = 3.355443200e+07, /* 0x4c000000 */
21twom25 = 2.9802322388e-08, /* 0x33000000 */
22huge = 1.0e+30,
23tiny = 1.0e-30;
24
25float
26__scalblnf (float x, long int n)
27{
28 int32_t k,ix;
29 GET_FLOAT_WORD(ix,x);
30 k = (ix&0x7f800000)>>23; /* extract exponent */
31 if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
32 if ((ix&0x7fffffff)==0) return x; /* +-0 */
33 x *= two25;
34 GET_FLOAT_WORD(ix,x);
35 k = ((ix&0x7f800000)>>23) - 25;
36 }
37 if (__builtin_expect(k==0xff, 0)) return x+x; /* NaN or Inf */
38 if (__builtin_expect(n< -50000, 0))
39 return tiny*copysignf(tiny,x); /*underflow*/
40 if (__builtin_expect(n> 50000 || k+n > 0xfe, 0))
41 return huge*copysignf(huge,x); /* overflow */
42 /* Now k and n are bounded we know that k = k+n does not
43 overflow. */
44 k = k+n;
45 if (__builtin_expect(k > 0, 1)) /* normal result */
46 {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
47 if (k <= -25)
48 return tiny*copysignf(tiny,x); /*underflow*/
49 k += 25; /* subnormal result */
50 SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
51 return x*twom25;
52}
53