xref: /minix3/lib/libc/arch/vax/gen/ldexp.S (revision e415d488727a332a2c69df018aa35e2cecf4148a)
1/*
2 * Copyright (c) 1983, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30/*
31 * double ldexp (value, exp)
32 * double value;
33 * int exp;
34 *
35 * Ldexp returns value*2**exp, if that result is in range.
36 * If underflow occurs, it returns zero.  If overflow occurs,
37 * it returns a value of appropriate sign and largest
38 * possible magnitude.  In case of either overflow or underflow,
39 * errno is set to ERANGE.  Note that errno is not modified if
40 * no error occurs.
41 */
42
43#include "DEFS.h"
44#include "assym.h"
45
46#if defined(LIBC_SCCS) && !defined(lint)
47	/*.asciz "@(#)ldexp.s	8.1 (Berkeley) 6/4/93" */
48RCSID("$NetBSD: ldexp.S,v 1.7 2011/01/25 02:38:15 matt Exp $")
49#endif /* LIBC_SCCS and not lint */
50
51#ifndef _REENTRANT
52	.globl	_C_LABEL(errno)
53#endif
54
55ENTRY(ldexp, 0)
56	movd	4(%ap),%r0	/* fetch "value" */
57	extzv	$7,$8,%r0,%r2	/* %r2 := biased exponent */
58	jeql	1f		/* if zero, done */
59
60	addl2	12(%ap),%r2	/* %r2 := new biased exponent */
61	jleq	2f		/* if <= 0, underflow */
62	cmpl	%r2,$256		/* otherwise check if too big */
63	jgeq	3f		/* jump if overflow */
64	insv	%r2,$7,$8,%r0	/* put exponent back in result */
651:
66	ret
672:
68	clrd	%r0
69	jbr	1f
703:
71	/*
72	 * The largest number that can be represented in a long floating
73	 * number.  This is given in hex in order to avoid floating
74	 * conversions
75	 */
76	movq	$0x7fffffffffffffff,%r0	 /* largest possible floating magnitude */
77	jbc	$15,4(%ap),1f	/* jump if argument was positive */
78	mnegd	%r0,%r0		/* if arg < 0, make result negative */
791:
80#ifdef _REENTRANT
81	pushl	%r0
82	calls	$0,_C_LABEL(__errno)
83	movl	$ ERANGE,(%r0)
84	movl	(%sp)+,%r0
85#else
86	movl	$ ERANGE,_C_LABEL(errno)
87#endif
88	ret
89END(ldexp)
90