+++ /dev/null
-/** @file\r
- Compute acos(x) using ieee FP math.\r
-\r
- Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>\r
- This program and the accompanying materials are licensed and made available under\r
- the terms and conditions of the BSD License that accompanies this distribution.\r
- The full text of the license may be found at\r
- http://opensource.org/licenses/bsd-license.\r
-\r
- THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
- WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\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
- e_acos.c 5.1 93/09/24\r
- NetBSD: e_acos.c,v 1.12 2002/05/26 22:01:47 wiz Exp\r
- */\r
-#if defined(_MSC_VER) /* Handle Microsoft VC++ compiler specifics. */\r
- // Keep older compilers quiet about floating-point divide-by-zero\r
- #pragma warning ( disable : 4723 )\r
-#endif\r
-\r
-#include <LibConfig.h>\r
-#include <sys/EfiCdefs.h>\r
-\r
-/* __ieee754_acos(x)\r
- * Method :\r
- * acos(x) = pi/2 - asin(x)\r
- * acos(-x) = pi/2 + asin(x)\r
- * For |x|<=0.5\r
- * acos(x) = pi/2 - (x + x*x^2*R(x^2)) (see asin.c)\r
- * For x>0.5\r
- * acos(x) = pi/2 - (pi/2 - 2asin(sqrt((1-x)/2)))\r
- * = 2asin(sqrt((1-x)/2))\r
- * = 2s + 2s*z*R(z) ...z=(1-x)/2, s=sqrt(z)\r
- * = 2f + (2c + 2s*z*R(z))\r
- * where f=hi part of s, and c = (z-f*f)/(s+f) is the correction term\r
- * for f so that f+c ~ sqrt(z).\r
- * For x<-0.5\r
- * acos(x) = pi - 2asin(sqrt((1-|x|)/2))\r
- * = pi - 0.5*(s+s*z*R(z)), where z=(1-|x|)/2,s=sqrt(z)\r
- *\r
- * Special cases:\r
- * if x is NaN, return x itself;\r
- * if |x|>1, return NaN with invalid signal.\r
- *\r
- * Function needed: __ieee754_sqrt\r
- */\r
-\r
-#include "math.h"\r
-#include "math_private.h"\r
-\r
-static const double\r
-one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */\r
-pi = 3.14159265358979311600e+00, /* 0x400921FB, 0x54442D18 */\r
-pio2_hi = 1.57079632679489655800e+00, /* 0x3FF921FB, 0x54442D18 */\r
-pio2_lo = 6.12323399573676603587e-17, /* 0x3C91A626, 0x33145C07 */\r
-pS0 = 1.66666666666666657415e-01, /* 0x3FC55555, 0x55555555 */\r
-pS1 = -3.25565818622400915405e-01, /* 0xBFD4D612, 0x03EB6F7D */\r
-pS2 = 2.01212532134862925881e-01, /* 0x3FC9C155, 0x0E884455 */\r
-pS3 = -4.00555345006794114027e-02, /* 0xBFA48228, 0xB5688F3B */\r
-pS4 = 7.91534994289814532176e-04, /* 0x3F49EFE0, 0x7501B288 */\r
-pS5 = 3.47933107596021167570e-05, /* 0x3F023DE1, 0x0DFDF709 */\r
-qS1 = -2.40339491173441421878e+00, /* 0xC0033A27, 0x1C8A2D4B */\r
-qS2 = 2.02094576023350569471e+00, /* 0x40002AE5, 0x9C598AC8 */\r
-qS3 = -6.88283971605453293030e-01, /* 0xBFE6066C, 0x1B8D0159 */\r
-qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */\r
-\r
-double\r
-__ieee754_acos(double x)\r
-{\r
- double z,p,q,r,w,s,c,df;\r
- int32_t hx,ix;\r
- GET_HIGH_WORD(hx,x);\r
- ix = hx&0x7fffffff;\r
- if(ix>=0x3ff00000) { /* |x| >= 1 */\r
- u_int32_t lx;\r
-\r
- GET_LOW_WORD(lx,x);\r
- if(((ix-0x3ff00000)|lx)==0) { /* |x|==1 */\r
- if(hx>0) return 0.0; /* acos(1) = 0 */\r
- else return pi+2.0*pio2_lo; /* acos(-1)= pi */\r
- }\r
- return (x-x)/(x-x); /* acos(|x|>1) is NaN */\r
- }\r
- if(ix<0x3fe00000) { /* |x| < 0.5 */\r
- if(ix<=0x3c600000) return pio2_hi+pio2_lo; /*if|x|<2**-57*/\r
- z = x*x;\r
- p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));\r
- q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));\r
- r = p/q;\r
- return pio2_hi - (x - (pio2_lo-x*r));\r
- }\r
- else if (hx<0) { /* x < -0.5 */\r
- z = (one+x)*0.5;\r
- p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));\r
- q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));\r
- s = __ieee754_sqrt(z);\r
- r = p/q;\r
- w = r*s-pio2_lo;\r
- return pi - 2.0*(s+w);\r
- }\r
- else { /* x > 0.5 */\r
- z = (one-x)*0.5;\r
- s = __ieee754_sqrt(z);\r
- df = s;\r
- SET_LOW_WORD(df,0);\r
- c = (z-df*df)/(s+df);\r
- p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));\r
- q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));\r
- r = p/q;\r
- w = r*s+c;\r
- return 2.0*(df+w);\r
- }\r
-}\r
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