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/* $NetBSD: n_tan.S,v 1.1 1995/10/10 23:40:31 ragge Exp $ */
/*
* Copyright (c) 1985, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tan.s 8.1 (Berkeley) 6/4/93
*/
/* This is the implementation of Peter Tang's double precision
* tangent for the VAX using Bob Corbett's argument reduction.
*
* Notes:
* under 1,024,000 random arguments testing on [0,2*pi]
* tan() observed maximum error = 2.15 ulps
*
* double tan(arg)
* double arg;
* method: true range reduction to [-pi/4,pi/4], P. Tang & B. Corbett
* S. McDonald, April 4, 1985
*/
.globl _tan
.text
.align 1
_tan: .word 0xffc # save r2-r11
movq 4(ap),r0
bicw3 $0x807f,r0,r2
beql 1f # if x is zero or reserved operand then return x
/*
* Save the PSL's IV & FU bits on the stack.
*/
movpsl r2
bicw3 $0xff9f,r2,-(sp)
/*
* Clear the IV & FU bits.
*/
bicpsw $0x0060
jsb libm$argred
/*
* At this point,
* r0 contains the quadrant number, 0, 1, 2, or 3;
* r2/r1 contains the reduced argument as a D-format number;
* r3 contains a F-format extension to the reduced argument;
*
* Save r3/r0 so that we can call cosine after calling sine.
*/
movq r2,-(sp)
movq r0,-(sp)
/*
* Call sine. r4 = 0 implies sine.
*/
movl $0,r4
jsb libm$sincos
/*
* Save sin(x) in r11/r10 .
*/
movd r0,r10
/*
* Call cosine. r4 = 1 implies cosine.
*/
movq (sp)+,r0
movq (sp)+,r2
movl $1,r4
jsb libm$sincos
divd3 r0,r10,r0
bispsw (sp)+
1: ret
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