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annotate src/libm/s_cos.c @ 3409:c8f580ebc96a

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Adam Strzelecki to SDL Sending a patch for fullscreen Mac OS X SDL 1.3 (SVN) Cocoa mouse position handling. In fullscreen mouse coordinates should be relative to SCREEN not to the window, which doesn't really occupy fullscreen. Without this patch mouse position (especially Y) was totally incorrect (shifted) in fullscreen.
author Sam Lantinga <slouken@libsdl.org>
date Thu, 22 Oct 2009 04:46:11 +0000
parents dc1eb82ffdaa
children
rev   line source
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1 /* @(#)s_cos.c 5.1 93/09/24 */
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2 /*
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3 * ====================================================
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4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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5 *
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6 * Developed at SunPro, a Sun Microsystems, Inc. business.
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7 * Permission to use, copy, modify, and distribute this
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8 * software is freely granted, provided that this notice
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9 * is preserved.
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10 * ====================================================
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11 */
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12
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13 #if defined(LIBM_SCCS) && !defined(lint)
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14 static const char rcsid[] =
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15 "$NetBSD: s_cos.c,v 1.7 1995/05/10 20:47:02 jtc Exp $";
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16 #endif
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17
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18 /* cos(x)
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19 * Return cosine function of x.
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20 *
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21 * kernel function:
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22 * __kernel_sin ... sine function on [-pi/4,pi/4]
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23 * __kernel_cos ... cosine function on [-pi/4,pi/4]
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24 * __ieee754_rem_pio2 ... argument reduction routine
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25 *
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26 * Method.
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27 * Let S,C and T denote the sin, cos and tan respectively on
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28 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
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29 * in [-pi/4 , +pi/4], and let n = k mod 4.
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30 * We have
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31 *
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32 * n sin(x) cos(x) tan(x)
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33 * ----------------------------------------------------------
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34 * 0 S C T
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35 * 1 C -S -1/T
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36 * 2 -S -C T
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37 * 3 -C S -1/T
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38 * ----------------------------------------------------------
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39 *
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40 * Special cases:
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41 * Let trig be any of sin, cos, or tan.
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42 * trig(+-INF) is NaN, with signals;
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43 * trig(NaN) is that NaN;
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44 *
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45 * Accuracy:
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46 * TRIG(x) returns trig(x) nearly rounded
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47 */
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48
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49 #include "math.h"
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50 #include "math_private.h"
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51
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52 libm_hidden_proto(cos)
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53 #ifdef __STDC__
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54 double cos(double x)
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55 #else
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56 double cos(x)
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57 double x;
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58 #endif
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59 {
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60 double y[2], z = 0.0;
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61 int32_t n, ix;
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62
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63 /* High word of x. */
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64 GET_HIGH_WORD(ix, x);
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65
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66 /* |x| ~< pi/4 */
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67 ix &= 0x7fffffff;
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68 if (ix <= 0x3fe921fb)
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69 return __kernel_cos(x, z);
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70
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71 /* cos(Inf or NaN) is NaN */
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72 else if (ix >= 0x7ff00000)
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73 return x - x;
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74
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75 /* argument reduction needed */
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76 else {
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77 n = __ieee754_rem_pio2(x, y);
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78 switch (n & 3) {
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79 case 0:
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80 return __kernel_cos(y[0], y[1]);
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81 case 1:
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82 return -__kernel_sin(y[0], y[1], 1);
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83 case 2:
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84 return -__kernel_cos(y[0], y[1]);
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85 default:
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86 return __kernel_sin(y[0], y[1], 1);
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87 }
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88 }
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89 }
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90
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91 libm_hidden_def(cos)