2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
9 * ====================================================
13 * scalbln(double x, long n)
14 * scalbln(x,n) returns x * 2**n computed by exponent
15 * manipulation rather than by actually performing an
16 * exponentiation or a multiplication.
20 #include "math_private.h"
23 two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
24 twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
28 double scalbln(double x, long n)
32 EXTRACT_WORDS(hx, lx, x);
33 k = (hx & 0x7ff00000) >> 20; /* extract exponent */
34 if (k == 0) { /* 0 or subnormal x */
35 if ((lx | (hx & 0x7fffffff)) == 0)
39 k = ((hx & 0x7ff00000) >> 20) - 54;
42 return x + x; /* NaN or Inf */
45 return huge * copysign(huge, x); /* overflow */
47 return tiny * copysign(tiny, x); /* underflow */
48 if (k > 0) { /* normal result */
49 SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
53 if (n > 50000) /* in case integer overflow in n+k */
54 return huge * copysign(huge, x); /* overflow */
55 return tiny * copysign(tiny, x); /* underflow */
57 k += 54; /* subnormal result */
58 SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
61 libm_hidden_def(scalbln)
63 #if LONG_MAX == INT_MAX
64 /* strong_alias(scalbln, scalbn) - "error: conflicting types for 'scalbn'"
65 * because it tries to declare "typeof(scalbln) scalbn;"
66 * which tries to give "long" parameter to scalbn.
69 __typeof(scalbn) scalbn __attribute__((alias("scalbln")));
71 double scalbn(double x, int n)
76 libm_hidden_def(scalbn)