22 /*
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 */
25 /*
26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
28 */
29
30 /*
31 * log2l(x)
32 * RETURN THE BASE 2 LOGARITHM OF X
33 *
34 * Method:
35 * purge off 0,INF, and NaN.
36 * n = ilogb(x)
37 * if (n<0) n+=1
38 * z = scalbn(x,-n)
39 * LOG2(x) = n + (1/ln2)*log(x)
40 */
41
42 #pragma weak log2l = __log2l
43
44 #include "libm.h"
45 #include "longdouble.h"
46
47 static const long double
48 zero = 0.0L,
49 half = 0.5L,
50 one = 1.0L,
51 invln2 = 1.442695040888963407359924681001892137427e+0000L;
52
53 long double
54 log2l(long double x) {
55 int n;
56
57 if (x == zero || !finitel(x))
58 return (logl(x));
59 n = ilogbl(x);
60 if (n < 0)
61 n += 1;
62 x = scalbnl(x, -n);
|
22 /*
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 */
25 /*
26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
28 */
29
30 /*
31 * log2l(x)
32 * RETURN THE BASE 2 LOGARITHM OF X
33 *
34 * Method:
35 * purge off 0,INF, and NaN.
36 * n = ilogb(x)
37 * if (n<0) n+=1
38 * z = scalbn(x,-n)
39 * LOG2(x) = n + (1/ln2)*log(x)
40 */
41
42 #pragma weak __log2l = log2l
43
44 #include "libm.h"
45 #include "longdouble.h"
46
47 static const long double
48 zero = 0.0L,
49 half = 0.5L,
50 one = 1.0L,
51 invln2 = 1.442695040888963407359924681001892137427e+0000L;
52
53 long double
54 log2l(long double x) {
55 int n;
56
57 if (x == zero || !finitel(x))
58 return (logl(x));
59 n = ilogbl(x);
60 if (n < 0)
61 n += 1;
62 x = scalbnl(x, -n);
|