Standard Libraries for EDK II.

This set of three packages: AppPkg, StdLib, StdLibPrivateInternalFiles; contains the implementation of libraries based upon non-UEFI standards such as ISO/IEC-9899, the library portion of the C Language Standard, POSIX, etc.

AppPkg contains applications that make use of the standard libraries defined in the StdLib Package.

StdLib contains header (include) files and the implementations of the standard libraries.

StdLibPrivateInternalFiles contains files for the exclusive use of the library implementations in StdLib.  These files should never be directly referenced from applications or other code.


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11600 6f19259b-4bc3-4df7-8a09-765794883524

StdLib/LibC/Math/s_cos.c

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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.
+ * ====================================================
+ */
+#include  <LibConfig.h>
+#include  <sys/EfiCdefs.h>
+#if defined(LIBM_SCCS) && !defined(lint)
+__RCSID("$NetBSD: s_cos.c,v 1.10 2002/05/26 22:01:54 wiz 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"
+
+double
+cos(double x)
+{
+  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);
+      }
+  }
+}