Mercurial > sdl-ios-xcode
view src/libm/s_cos.c @ 2960:91708bc14aab
It's probably not worth pushing palettized textures. The memory optimization
isn't worth the effort on modern hardware with the sorts of games that would
be using the SDL 1.3 texture API.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Fri, 02 Jan 2009 09:27:36 +0000 |
parents | a98604b691c8 |
children | dc1eb82ffdaa |
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/* @(#)s_cos.c 5.1 93/09/24 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ #if defined(LIBM_SCCS) && !defined(lint) static char rcsid[] = "$NetBSD: s_cos.c,v 1.7 1995/05/10 20:47:02 jtc Exp $"; #endif /* cos(x) * Return cosine function of x. * * kernel function: * __kernel_sin ... sine function on [-pi/4,pi/4] * __kernel_cos ... cosine function on [-pi/4,pi/4] * __ieee754_rem_pio2 ... argument reduction routine * * Method. * Let S,C and T denote the sin, cos and tan respectively on * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 * in [-pi/4 , +pi/4], and let n = k mod 4. * We have * * n sin(x) cos(x) tan(x) * ---------------------------------------------------------- * 0 S C T * 1 C -S -1/T * 2 -S -C T * 3 -C S -1/T * ---------------------------------------------------------- * * Special cases: * Let trig be any of sin, cos, or tan. * trig(+-INF) is NaN, with signals; * trig(NaN) is that NaN; * * Accuracy: * TRIG(x) returns trig(x) nearly rounded */ #include "math.h" #include "math_private.h" libm_hidden_proto(cos) #ifdef __STDC__ double cos(double x) #else double cos(x) double x; #endif { double y[2], z = 0.0; int32_t n, ix; /* High word of x. */ GET_HIGH_WORD(ix, x); /* |x| ~< pi/4 */ ix &= 0x7fffffff; if (ix <= 0x3fe921fb) return __kernel_cos(x, z); /* cos(Inf or NaN) is NaN */ else if (ix >= 0x7ff00000) return x - x; /* argument reduction needed */ else { n = __ieee754_rem_pio2(x, y); switch (n & 3) { case 0: return __kernel_cos(y[0], y[1]); case 1: return -__kernel_sin(y[0], y[1], 1); case 2: return -__kernel_cos(y[0], y[1]); default: return __kernel_sin(y[0], y[1], 1); } } } libm_hidden_def(cos)