125c28e83SPiotr Jasiukajtis /*
225c28e83SPiotr Jasiukajtis * CDDL HEADER START
325c28e83SPiotr Jasiukajtis *
425c28e83SPiotr Jasiukajtis * The contents of this file are subject to the terms of the
525c28e83SPiotr Jasiukajtis * Common Development and Distribution License (the "License").
625c28e83SPiotr Jasiukajtis * You may not use this file except in compliance with the License.
725c28e83SPiotr Jasiukajtis *
825c28e83SPiotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
925c28e83SPiotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
1025c28e83SPiotr Jasiukajtis * See the License for the specific language governing permissions
1125c28e83SPiotr Jasiukajtis * and limitations under the License.
1225c28e83SPiotr Jasiukajtis *
1325c28e83SPiotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
1425c28e83SPiotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1525c28e83SPiotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
1625c28e83SPiotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
1725c28e83SPiotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
1825c28e83SPiotr Jasiukajtis *
1925c28e83SPiotr Jasiukajtis * CDDL HEADER END
2025c28e83SPiotr Jasiukajtis */
2125c28e83SPiotr Jasiukajtis
2225c28e83SPiotr Jasiukajtis /*
2325c28e83SPiotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
2425c28e83SPiotr Jasiukajtis */
2525c28e83SPiotr Jasiukajtis /*
2625c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
2725c28e83SPiotr Jasiukajtis * Use is subject to license terms.
2825c28e83SPiotr Jasiukajtis */
2925c28e83SPiotr Jasiukajtis
30*ddc0e0b5SRichard Lowe #pragma weak __log10l = log10l
3125c28e83SPiotr Jasiukajtis
3225c28e83SPiotr Jasiukajtis /*
3325c28e83SPiotr Jasiukajtis * log10l(X)
3425c28e83SPiotr Jasiukajtis *
3525c28e83SPiotr Jasiukajtis * Method :
3625c28e83SPiotr Jasiukajtis * Let log10_2hi = leading 98(SPARC)/49(x86) bits of log10(2) and
3725c28e83SPiotr Jasiukajtis * log10_2lo = log10(2) - log10_2hi,
3825c28e83SPiotr Jasiukajtis * ivln10 = 1/log(10) rounded.
3925c28e83SPiotr Jasiukajtis * Then
4025c28e83SPiotr Jasiukajtis * n = ilogb(x),
4125c28e83SPiotr Jasiukajtis * if (n<0) n = n+1;
4225c28e83SPiotr Jasiukajtis * x = scalbn(x,-n);
4325c28e83SPiotr Jasiukajtis * LOG10(x) := n*log10_2hi + (n*log10_2lo + ivln10*log(x))
4425c28e83SPiotr Jasiukajtis *
4525c28e83SPiotr Jasiukajtis * Note1:
4625c28e83SPiotr Jasiukajtis * For fear of destroying log10(10**n)=n, the rounding mode is
4725c28e83SPiotr Jasiukajtis * set to Round-to-Nearest.
4825c28e83SPiotr Jasiukajtis *
4925c28e83SPiotr Jasiukajtis * Special cases:
5025c28e83SPiotr Jasiukajtis * log10(x) is NaN with signal if x < 0;
5125c28e83SPiotr Jasiukajtis * log10(+INF) is +INF with no signal; log10(0) is -INF with signal;
5225c28e83SPiotr Jasiukajtis * log10(NaN) is that NaN with no signal;
5325c28e83SPiotr Jasiukajtis * log10(10**N) = N for N=0,1,...,22.
5425c28e83SPiotr Jasiukajtis *
5525c28e83SPiotr Jasiukajtis * Constants:
5625c28e83SPiotr Jasiukajtis * The hexadecimal values are the intended ones for the following constants.
5725c28e83SPiotr Jasiukajtis * The decimal values may be used, provided that the compiler will convert
5825c28e83SPiotr Jasiukajtis * from decimal to binary accurately enough to produce the hexadecimal values
5925c28e83SPiotr Jasiukajtis * shown.
6025c28e83SPiotr Jasiukajtis */
6125c28e83SPiotr Jasiukajtis
6225c28e83SPiotr Jasiukajtis #include "libm.h"
6325c28e83SPiotr Jasiukajtis #include "longdouble.h"
6425c28e83SPiotr Jasiukajtis
6525c28e83SPiotr Jasiukajtis #if defined(__x86)
6625c28e83SPiotr Jasiukajtis #define __swapRD __swap87RD
6725c28e83SPiotr Jasiukajtis #endif
6825c28e83SPiotr Jasiukajtis extern enum fp_direction_type __swapRD(enum fp_direction_type);
6925c28e83SPiotr Jasiukajtis
7025c28e83SPiotr Jasiukajtis static const long double
7125c28e83SPiotr Jasiukajtis zero = 0.0L,
7225c28e83SPiotr Jasiukajtis ivln10 = 4.342944819032518276511289189166050822944e-0001L,
7325c28e83SPiotr Jasiukajtis one = 1.0L,
7425c28e83SPiotr Jasiukajtis #if defined(__x86)
7525c28e83SPiotr Jasiukajtis log10_2hi = 3.010299956639803653501985536422580480576e-01L,
7625c28e83SPiotr Jasiukajtis log10_2lo = 8.298635403410822349787106337291183585413e-16L;
7725c28e83SPiotr Jasiukajtis #elif defined(__sparc)
7825c28e83SPiotr Jasiukajtis log10_2hi = 3.010299956639811952137388947242098603469e-01L,
7925c28e83SPiotr Jasiukajtis log10_2lo = 2.831664213089468167896664371953210945664e-31L;
8025c28e83SPiotr Jasiukajtis #else
8125c28e83SPiotr Jasiukajtis #error Unknown Architecture!
8225c28e83SPiotr Jasiukajtis #endif
8325c28e83SPiotr Jasiukajtis
8425c28e83SPiotr Jasiukajtis long double
log10l(long double x)8525c28e83SPiotr Jasiukajtis log10l(long double x) {
8625c28e83SPiotr Jasiukajtis long double y, z;
8725c28e83SPiotr Jasiukajtis enum fp_direction_type rd;
8825c28e83SPiotr Jasiukajtis int n;
8925c28e83SPiotr Jasiukajtis
9025c28e83SPiotr Jasiukajtis if (!finitel(x))
9125c28e83SPiotr Jasiukajtis return (x + fabsl(x)); /* x is +-INF or NaN */
9225c28e83SPiotr Jasiukajtis else if (x > zero) {
9325c28e83SPiotr Jasiukajtis n = ilogbl(x);
9425c28e83SPiotr Jasiukajtis if (n < 0)
9525c28e83SPiotr Jasiukajtis n += 1;
9625c28e83SPiotr Jasiukajtis rd = __swapRD(fp_nearest);
9725c28e83SPiotr Jasiukajtis y = n;
9825c28e83SPiotr Jasiukajtis x = scalbnl(x, -n);
9925c28e83SPiotr Jasiukajtis z = y * log10_2lo + ivln10 * logl(x);
10025c28e83SPiotr Jasiukajtis z += y * log10_2hi;
10125c28e83SPiotr Jasiukajtis if (rd != fp_nearest)
10225c28e83SPiotr Jasiukajtis (void) __swapRD(rd);
10325c28e83SPiotr Jasiukajtis return (z);
10425c28e83SPiotr Jasiukajtis } else if (x == zero) /* -INF */
10525c28e83SPiotr Jasiukajtis return (-one / zero);
10625c28e83SPiotr Jasiukajtis else /* x <0, return NaN */
10725c28e83SPiotr Jasiukajtis return (zero / zero);
10825c28e83SPiotr Jasiukajtis }
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