usr/src/lib/libm/common/R/cosf.c

   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  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23  */
  24 /*
  25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28
  29 #pragma weak __cosf = cosf
  30
  31 /*
  32  * See sincosf.c
  33  */
  34
  35 #include "libm.h"
  36
  37 extern const int _TBL_ipio2_inf[];
  38 extern int __rem_pio2m(double *, double *, int, int, int, const int *);
  39 #if defined(__i386) && !defined(__amd64)
  40 extern int __swapRP(int);
  41 #endif
  42
  43 static const double C[] = {
  44         1.85735322054308378716204874632872525989806770558e-0003,
  45         -1.95035094218403635082921458859320791358115801259e-0004,
  46         5.38400550766074785970952495168558701485841707252e+0002,
  47         -3.31975110777873728964197739157371509422022905947e+0001,
  48         1.09349482127188401868272000389539985058873853699e-0003,
  49         -5.03324285989964979398034700054920226866107675091e-0004,
  50         2.43792880266971107750418061559602239831538067410e-0005,
  51         9.14499072605666582228127405245558035523741471271e+0002,
  52         -3.63151270591815439197122504991683846785293207730e+0001,
  53         0.636619772367581343075535,     /* 2^ -1  * 1.45F306DC9C883 */
  54         0.5,
  55         1.570796326734125614166,        /* 2^  0  * 1.921FB54400000 */
  56         6.077100506506192601475e-11,    /* 2^-34  * 1.0B4611A626331 */
  57 };
  58
  59 #define S0      C[0]
  60 #define S1      C[1]
  61 #define S2      C[2]
  62 #define S3      C[3]
  63 #define C0      C[4]
  64 #define C1      C[5]
  65 #define C2      C[6]
  66 #define C3      C[7]
  67 #define C4      C[8]
  68 #define invpio2 C[9]
  69 #define half    C[10]
  70 #define pio2_1  C[11]
  71 #define pio2_t  C[12]
  72
  73 float
  74 cosf(float x)
  75 {
  76         double  y, z, w;
  77         float   f;
  78         int     n, ix, hx, hy;
  79         volatile int i __unused;
  80
  81         hx = *((int *)&x);
  82         ix = hx & 0x7fffffff;
  83
  84         y = (double)x;
  85
  86         if (ix <= 0x4016cbe4) {         /* |x| < 3*pi/4 */
  87                 if (ix <= 0x3f490fdb) {         /* |x| < pi/4 */
  88                         if (ix <= 0x39800000) { /* |x| <= 2**-12 */
  89                                 i = (int)y;
  90                                 return (1.0f);
  91                         }
  92                         z = y * y;
  93                         return ((float)(((C0 + z * C1) + (z * z) * C2) *
  94                             (C3 + z * (C4 + z))));
  95                 } else if (hx > 0) {
  96                         y = (y - pio2_1) - pio2_t;
  97                         z = y * y;
  98                         return ((float)-((y * (S0 + z * S1)) *
  99                             (S2 + z * (S3 + z))));
 100                 } else {
 101                         y = (y + pio2_1) + pio2_t;
 102                         z = y * y;
 103                         return ((float)((y * (S0 + z * S1)) *
 104                             (S2 + z * (S3 + z))));
 105                 }
 106         } else if (ix <= 0x49c90fdb) {  /* |x| < 2^19*pi */
 107 #if defined(__i386) && !defined(__amd64)
 108                 int     rp;
 109
 110                 rp = __swapRP(fp_extended);
 111 #endif
 112                 w = y * invpio2;
 113                 if (hx < 0)
 114                         n = (int)(w - half);
 115                 else
 116                         n = (int)(w + half);
 117                 y = (y - n * pio2_1) - n * pio2_t;
 118                 n++;
 119 #if defined(__i386) && !defined(__amd64)
 120                 if (rp != fp_extended)
 121                         (void) __swapRP(rp);
 122 #endif
 123         } else {
 124                 if (ix >= 0x7f800000)
 125                         return (x / x); /* cos(Inf or NaN) is NaN */
 126                 hy = ((int *)&y)[HIWORD];
 127                 n = ((hy >> 20) & 0x7ff) - 1046;
 128                 ((int *)&w)[HIWORD] = (hy & 0xfffff) | 0x41600000;
 129                 ((int *)&w)[LOWORD] = ((int *)&y)[LOWORD];
 130                 n = __rem_pio2m(&w, &y, n, 1, 0, _TBL_ipio2_inf) + 1;
 131         }
 132
 133         if (n & 1) {
 134                 /* compute cos y */
 135                 z = y * y;
 136                 f = (float)(((C0 + z * C1) + (z * z) * C2) *
 137                     (C3 + z * (C4 + z)));
 138         } else {
 139                 /* compute sin y */
 140                 z = y * y;
 141                 f = (float)((y * (S0 + z * S1)) * (S2 + z * (S3 + z)));
 142         }
 143
 144         return ((n & 2)? -f : f);
 145 }