1/* $NetBSD: n_tan.S,v 1.3 1999/07/02 15:37:35 simonb 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. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by the University of 17 * California, Berkeley and its contributors. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)tan.s 8.1 (Berkeley) 6/4/93 35 */ 36 37/* This is the implementation of Peter Tang's double precision 38 * tangent for the VAX using Bob Corbett's argument reduction. 39 * 40 * Notes: 41 * under 1,024,000 random arguments testing on [0,2*pi] 42 * tan() observed maximum error = 2.15 ulps 43 * 44 * double tan(arg) 45 * double arg; 46 * method: true range reduction to [-pi/4,pi/4], P. Tang & B. Corbett 47 * S. McDonald, April 4, 1985 48 */ 49 .text 50 .align 1 51 .globl _tan 52 .type _tan,@function 53 54_tan: .word 0xffc # save r2-r11 55 movq 4(ap),r0 56 bicw3 $0x807f,r0,r2 57 beql 1f # if x is zero or reserved operand then return x 58/* 59 * Save the PSL's IV & FU bits on the stack. 60 */ 61 movpsl r2 62 bicw3 $0xff9f,r2,-(sp) 63/* 64 * Clear the IV & FU bits. 65 */ 66 bicpsw $0x0060 67 jsb libm$argred 68/* 69 * At this point, 70 * r0 contains the quadrant number, 0, 1, 2, or 3; 71 * r2/r1 contains the reduced argument as a D-format number; 72 * r3 contains a F-format extension to the reduced argument; 73 * 74 * Save r3/r0 so that we can call cosine after calling sine. 75 */ 76 movq r2,-(sp) 77 movq r0,-(sp) 78/* 79 * Call sine. r4 = 0 implies sine. 80 */ 81 movl $0,r4 82 jsb libm$sincos 83/* 84 * Save sin(x) in r11/r10 . 85 */ 86 movd r0,r10 87/* 88 * Call cosine. r4 = 1 implies cosine. 89 */ 90 movq (sp)+,r0 91 movq (sp)+,r2 92 movl $1,r4 93 jsb libm$sincos 94 divd3 r0,r10,r0 95 bispsw (sp)+ 961: ret 97