Standard Libraries for EDK II.

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

diff --git a/StdLib/LibC/Math/k_sin.c b/StdLib/LibC/Math/k_sin.c
new file mode 100644 (file)
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+++ b/StdLib/LibC/Math/k_sin.c
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+/* @(#)k_sin.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: k_sin.c,v 1.11 2002/05/26 22:01:53 wiz Exp $");\r
+#endif\r
+\r
+/* __kernel_sin( x, y, iy)\r
+ * kernel sin function on [-pi/4, pi/4], pi/4 ~ 0.7854\r
+ * Input x is assumed to be bounded by ~pi/4 in magnitude.\r
+ * Input y is the tail of x.\r
+ * Input iy indicates whether y is 0. (if iy=0, y assume to be 0).\r
+ *\r
+ * Algorithm\r
+ *  1. Since sin(-x) = -sin(x), we need only to consider positive x.\r
+ *  2. if x < 2^-27 (hx<0x3e400000 0), return x with inexact if x!=0.\r
+ *  3. sin(x) is approximated by a polynomial of degree 13 on\r
+ *     [0,pi/4]\r
+ *                 3            13\r
+ *      sin(x) ~ x + S1*x + ... + S6*x\r
+ *     where\r
+ *\r
+ *  |sin(x)         2     4     6     8     10     12  |     -58\r
+ *  |----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x  +S6*x   )| <= 2\r
+ *  |  x                     |\r
+ *\r
+ *  4. sin(x+y) = sin(x) + sin'(x')*y\r
+ *        ~ sin(x) + (1-x*x/2)*y\r
+ *     For better accuracy, let\r
+ *         3      2      2      2      2\r
+ *    r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6))))\r
+ *     then                   3    2\r
+ *    sin(x) = x + (S1*x + (x *(r-y/2)+y))\r
+ */\r
+\r
+#include "math.h"\r
+#include "math_private.h"\r
+\r
+static const double\r
+half =  5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */\r
+S1  = -1.66666666666666324348e-01, /* 0xBFC55555, 0x55555549 */\r
+S2  =  8.33333333332248946124e-03, /* 0x3F811111, 0x1110F8A6 */\r
+S3  = -1.98412698298579493134e-04, /* 0xBF2A01A0, 0x19C161D5 */\r
+S4  =  2.75573137070700676789e-06, /* 0x3EC71DE3, 0x57B1FE7D */\r
+S5  = -2.50507602534068634195e-08, /* 0xBE5AE5E6, 0x8A2B9CEB */\r
+S6  =  1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */\r
+\r
+double\r
+__kernel_sin(double x, double y, int iy)\r
+{\r
+  double z,r,v;\r
+  int32_t ix;\r
+  GET_HIGH_WORD(ix,x);\r
+  ix &= 0x7fffffff;     /* high word of x */\r
+  if(ix<0x3e400000)     /* |x| < 2**-27 */\r
+     {if((int)x==0) return x;}    /* generate inexact */\r
+  z =  x*x;\r
+  v =  z*x;\r
+  r =  S2+z*(S3+z*(S4+z*(S5+z*S6)));\r
+  if(iy==0) return x+v*(S1+z*r);\r
+  else      return x-((z*(half*y-v*r)-y)-v*S1);\r
+}\r