1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate * CDDL HEADER START
3*0Sstevel@tonic-gate *
4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance
7*0Sstevel@tonic-gate * with the License.
8*0Sstevel@tonic-gate *
9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate * and limitations under the License.
13*0Sstevel@tonic-gate *
14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate *
20*0Sstevel@tonic-gate * CDDL HEADER END
21*0Sstevel@tonic-gate */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate * Copyright 1988 Sun Microsystems, Inc. All rights reserved.
24*0Sstevel@tonic-gate * Use is subject to license terms.
25*0Sstevel@tonic-gate */
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate /* Copyright (c) 1984 AT&T */
28*0Sstevel@tonic-gate /* All Rights Reserved */
29*0Sstevel@tonic-gate
30*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" /* from S5R2 2.7 */
31*0Sstevel@tonic-gate
32*0Sstevel@tonic-gate /*LINTLIBRARY*/
33*0Sstevel@tonic-gate /*
34*0Sstevel@tonic-gate * double ldexp (value, exp)
35*0Sstevel@tonic-gate * double value;
36*0Sstevel@tonic-gate * int exp;
37*0Sstevel@tonic-gate *
38*0Sstevel@tonic-gate * Ldexp returns value * 2**exp, if that result is in range.
39*0Sstevel@tonic-gate * If underflow occurs, it returns zero. If overflow occurs,
40*0Sstevel@tonic-gate * it returns a value of appropriate sign and largest single-
41*0Sstevel@tonic-gate * precision magnitude. In case of underflow or overflow,
42*0Sstevel@tonic-gate * the external int "errno" is set to ERANGE. Note that errno is
43*0Sstevel@tonic-gate * not modified if no error occurs, so if you intend to test it
44*0Sstevel@tonic-gate * after you use ldexp, you had better set it to something
45*0Sstevel@tonic-gate * other than ERANGE first (zero is a reasonable value to use).
46*0Sstevel@tonic-gate */
47*0Sstevel@tonic-gate
48*0Sstevel@tonic-gate #include <values.h>
49*0Sstevel@tonic-gate #include <errno.h>
50*0Sstevel@tonic-gate /* Largest signed long int power of 2 */
51*0Sstevel@tonic-gate #define MAXSHIFT (BITSPERBYTE * sizeof(long) - 2)
52*0Sstevel@tonic-gate
53*0Sstevel@tonic-gate extern double frexp();
54*0Sstevel@tonic-gate
55*0Sstevel@tonic-gate double
ldexp(value,exp)56*0Sstevel@tonic-gate ldexp(value, exp)
57*0Sstevel@tonic-gate register double value;
58*0Sstevel@tonic-gate register int exp;
59*0Sstevel@tonic-gate {
60*0Sstevel@tonic-gate int old_exp;
61*0Sstevel@tonic-gate
62*0Sstevel@tonic-gate if (exp == 0 || value == 0.0) /* nothing to do for zero */
63*0Sstevel@tonic-gate return (value);
64*0Sstevel@tonic-gate #if !(pdp11 || u3b5) /* pdp11 "cc" can't handle cast of
65*0Sstevel@tonic-gate double to void on pdp11 or 3b5 */
66*0Sstevel@tonic-gate (void)
67*0Sstevel@tonic-gate #endif
68*0Sstevel@tonic-gate frexp(value, &old_exp);
69*0Sstevel@tonic-gate if (exp > 0) {
70*0Sstevel@tonic-gate if (exp + old_exp > MAXBEXP) { /* overflow */
71*0Sstevel@tonic-gate errno = ERANGE;
72*0Sstevel@tonic-gate return ((double)(value < 0 ? MINDOUBLE : MAXDOUBLE));
73*0Sstevel@tonic-gate /*
74*0Sstevel@tonic-gate return ((double)(value < 0 ? -1.0e999 : 1.0e999));
75*0Sstevel@tonic-gate */
76*0Sstevel@tonic-gate }
77*0Sstevel@tonic-gate for ( ; exp > MAXSHIFT; exp -= MAXSHIFT)
78*0Sstevel@tonic-gate value *= (1L << MAXSHIFT);
79*0Sstevel@tonic-gate return (value * (1L << exp));
80*0Sstevel@tonic-gate }
81*0Sstevel@tonic-gate if (exp + old_exp < MINBEXP) { /* underflow */
82*0Sstevel@tonic-gate errno = ERANGE;
83*0Sstevel@tonic-gate return (0.0);
84*0Sstevel@tonic-gate }
85*0Sstevel@tonic-gate for ( ; exp < -MAXSHIFT; exp += MAXSHIFT)
86*0Sstevel@tonic-gate value *= 1.0/(1L << MAXSHIFT); /* mult faster than div */
87*0Sstevel@tonic-gate return (value / (1L << -exp));
88*0Sstevel@tonic-gate }
89