1/*	$NetBSD: n_tan.S,v 1.5 2002/02/24 01:06:21 matt Exp $	*/
2/*
3 * Copyright (c) 1985, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 *	@(#)tan.s	8.1 (Berkeley) 6/4/93
31 */
32
33#include <machine/asm.h>
34
35/*  This is the implementation of Peter Tang's double precision
36 *  tangent for the VAX using Bob Corbett's argument reduction.
37 *
38 *  Notes:
39 *       under 1,024,000 random arguments testing on [0,2*pi]
40 *       tan() observed maximum error = 2.15 ulps
41 *
42 * double tan(arg)
43 * double arg;
44 * method: true range reduction to [-pi/4,pi/4], P. Tang  &  B. Corbett
45 * S. McDonald, April 4,  1985
46 */
47ENTRY(tan, 0x0fc0)		# save %r6-%r11
48	movq	4(%ap),%r0
49	bicw3	$0x807f,%r0,%r2
50	beql	1f		# if x is zero or reserved operand then return x
51/*
52 * Save the PSL's IV & FU bits on the stack.
53 */
54	movpsl	%r2
55	bicw3	$0xff9f,%r2,-(%sp)
56/*
57 *  Clear the IV & FU bits.
58 */
59	bicpsw	$0x0060
60	jsb	_C_LABEL(__libm_argred)+2
61/*
62 *  At this point,
63 *	   %r0  contains the quadrant number, 0, 1, 2, or 3;
64 *	%r2/%r1  contains the reduced argument as a D-format number;
65 *  	   %r3  contains a F-format extension to the reduced argument;
66 *
67 *  Save  %r3/%r0  so that we can call cosine after calling sine.
68 */
69	movq	%r2,-(%sp)
70	movq	%r0,-(%sp)
71/*
72 *  Call sine.  %r4 = 0  implies sine.
73 */
74	movl	$0,%r4
75	jsb	_C_LABEL(__libm_sincos)+2
76/*
77 *  Save  sin(x)  in  %r11/%r10 .
78 */
79	movd	%r0,%r10
80/*
81 *  Call cosine.  %r4 = 1  implies cosine.
82 */
83	movq	(%sp)+,%r0
84	movq	(%sp)+,%r2
85	movl	$1,%r4
86	jsb	_C_LABEL(__libm_sincos)+2
87	divd3	%r0,%r10,%r0
88	bispsw	(%sp)+
891:	ret
90