1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #pragma weak __cosl = cosl 31 32 /* INDENT OFF */ 33 /* cosl(x) 34 * Table look-up algorithm by K.C. Ng, November, 1989. 35 * 36 * kernel function: 37 * __k_sinl ... sin function on [-pi/4,pi/4] 38 * __k_cosl ... cos function on [-pi/4,pi/4] 39 * __rem_pio2l ... argument reduction routine 40 * 41 * Method. 42 * Let S and C denote the sin and cos respectively on [-PI/4, +PI/4]. 43 * 1. Assume the argument x is reduced to y1+y2 = x-k*pi/2 in 44 * [-pi/2 , +pi/2], and let n = k mod 4. 45 * 2. Let S=S(y1+y2), C=C(y1+y2). Depending on n, we have 46 * 47 * n sin(x) cos(x) tan(x) 48 * ---------------------------------------------------------- 49 * 0 S C S/C 50 * 1 C -S -C/S 51 * 2 -S -C S/C 52 * 3 -C S -C/S 53 * ---------------------------------------------------------- 54 * 55 * Special cases: 56 * Let trig be any of sin, cos, or tan. 57 * trig(+-INF) is NaN, with signals; 58 * trig(NaN) is that NaN; 59 * 60 * Accuracy: 61 * computer TRIG(x) returns trig(x) nearly rounded. 62 */ 63 /* INDENT ON */ 64 65 #include "libm.h" 66 #include "longdouble.h" 67 68 #include <sys/isa_defs.h> 69 70 long double 71 cosl(long double x) { 72 long double y[2], z = 0.0L; 73 int n, ix; 74 int *px = (int *) &x; 75 76 /* trig(Inf or NaN) is NaN */ 77 if (!finitel(x)) 78 return x - x; 79 80 /* High word of x. */ 81 #if defined(__i386) || defined(__amd64) 82 XTOI(px, ix); 83 #else 84 ix = px[0]; 85 #endif 86 87 /* |x| ~< pi/4 */ 88 ix &= 0x7fffffff; 89 if (ix <= 0x3ffe9220) 90 return __k_cosl(x, z); 91 92 /* argument reduction needed */ 93 else { 94 n = __rem_pio2l(x, y); 95 switch (n & 3) { 96 case 0: 97 return __k_cosl(y[0], y[1]); 98 case 1: 99 return -__k_sinl(y[0], y[1]); 100 case 2: 101 return -__k_cosl(y[0], y[1]); 102 case 3: 103 return __k_sinl(y[0], y[1]); 104 /* NOTREACHED */ 105 } 106 } 107 return 0.0L; 108 } 109