NetBSD/lib/libm/vax/tan.S

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1993-08-14 17:42:09 +04:00
# Copyright (c) 1985 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. All advertising materials mentioning features or use of this software
# must display the following acknowledgement:
# This product includes software developed by the University of
# California, Berkeley and its contributors.
# 4. 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.
#
.data
.align 2
;_sccsid:
;.asciz "from: @(#)tan.s 1.1 (Berkeley) 8/21/85; 5.4 (ucb.elefunt) 10/9/90"
_rcsid:
.asciz "$Id: tan.S,v 1.1 1993/08/14 13:44:15 mycroft Exp $"
# 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