ArmPkg: ArmLib: purge incorrect ArmDrainWriteBuffer () alias

[mirror_edk2.git] / StdLib / LibC / Math / s_cos.c

/* @(#)s_cos.c 5.1 93/09/24 */\r
/*\r
 * ====================================================\r
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\r
 *\r
 * Developed at SunPro, a Sun Microsystems, Inc. business.\r
 * Permission to use, copy, modify, and distribute this\r
 * software is freely granted, provided that this notice\r
 * is preserved.\r
 * ====================================================\r
 */\r
#include  <LibConfig.h>\r
#include  <sys/EfiCdefs.h>\r
#if defined(LIBM_SCCS) && !defined(lint)\r
__RCSID("$NetBSD: s_cos.c,v 1.10 2002/05/26 22:01:54 wiz Exp $");\r
#endif\r
\r
/* cos(x)\r
 * Return cosine function of x.\r
 *\r
 * kernel function:\r
 *  __kernel_sin    ... sine function on [-pi/4,pi/4]\r
 *  __kernel_cos    ... cosine function on [-pi/4,pi/4]\r
 *  __ieee754_rem_pio2  ... argument reduction routine\r
 *\r
 * Method.\r
 *      Let S,C and T denote the sin, cos and tan respectively on\r
 *  [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2\r
 *  in [-pi/4 , +pi/4], and let n = k mod 4.\r
 *  We have\r
 *\r
 *          n        sin(x)      cos(x)        tan(x)\r
 *     ----------------------------------------------------------\r
 *      0        S     C     T\r
 *      1        C    -S    -1/T\r
 *      2       -S    -C     T\r
 *      3       -C     S    -1/T\r
 *     ----------------------------------------------------------\r
 *\r
 * Special cases:\r
 *      Let trig be any of sin, cos, or tan.\r
 *      trig(+-INF)  is NaN, with signals;\r
 *      trig(NaN)    is that NaN;\r
 *\r
 * Accuracy:\r
 *  TRIG(x) returns trig(x) nearly rounded\r
 */\r
\r
#include "math.h"\r
#include "math_private.h"\r
\r
double\r
cos(double x)\r
{\r
  double y[2],z=0.0;\r
  int32_t n, ix;\r
\r
    /* High word of x. */\r
  GET_HIGH_WORD(ix,x);\r
\r
    /* |x| ~< pi/4 */\r
  ix &= 0x7fffffff;\r
  if(ix <= 0x3fe921fb) return __kernel_cos(x,z);\r
\r
    /* cos(Inf or NaN) is NaN */\r
  else if (ix>=0x7ff00000) return x-x;\r
\r
    /* argument reduction needed */\r
  else {\r
      n = __ieee754_rem_pio2(x,y);\r
      switch(n&3) {\r
    case 0: return  __kernel_cos(y[0],y[1]);\r
    case 1: return -__kernel_sin(y[0],y[1],1);\r
    case 2: return -__kernel_cos(y[0],y[1]);\r
    default:\r
            return  __kernel_sin(y[0],y[1],1);\r
      }\r
  }\r
}\r