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| author | darylm503 <darylm503@6f19259b-4bc3-4df7-8a09-765794883524> | 2011-04-27 21:42:16 +0000 |
|---|---|---|
| committer | darylm503 <darylm503@6f19259b-4bc3-4df7-8a09-765794883524> | 2011-04-27 21:42:16 +0000 |
| commit | 2aa62f2bc9a9654687b377d9ca8a8c2c860a3852 (patch) | |
| tree | 62a0991a44327154fb88bf95bd6f7522053db7bb /StdLib/LibC/Math/e_log2.c | |
| parent | 98790d814871cc30bbd536673d3a0948047cd2f0 (diff) | |
| download | edk2-platforms-2aa62f2bc9a9654687b377d9ca8a8c2c860a3852.tar.xz | |
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
Diffstat (limited to 'StdLib/LibC/Math/e_log2.c')
| -rw-r--r-- | StdLib/LibC/Math/e_log2.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/StdLib/LibC/Math/e_log2.c b/StdLib/LibC/Math/e_log2.c new file mode 100644 index 0000000000..5d15cd3b01 --- /dev/null +++ b/StdLib/LibC/Math/e_log2.c @@ -0,0 +1,85 @@ +
+/* @(#)e_log.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, 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: e_log2.c,v 1.1 2005/07/21 12:55:58 christos Exp $");
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+#if defined(_MSC_VER) /* Handle Microsoft VC++ compiler specifics. */
+ // potential divide by 0 -- near line 53, (x-x)/zero is on purpose
+ #pragma warning ( disable : 4723 )
+#endif
+
+static const double
+ln2 = 0.6931471805599452862268,
+two54 = 1.80143985094819840000e+16, /* 43500000 00000000 */
+Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */
+Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */
+Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */
+Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */
+Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */
+Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */
+Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */
+
+static const double zero = 0.0;
+
+double
+__ieee754_log2(double x)
+{
+ double hfsq,f,s,z,R,w,t1,t2,dk;
+ int32_t k,hx,i,j;
+ u_int32_t lx;
+
+ EXTRACT_WORDS(hx,lx,x);
+
+ k=0;
+ if (hx < 0x00100000) { /* x < 2**-1022 */
+ if (((hx&0x7fffffff)|lx)==0)
+ return -two54/zero; /* log(+-0)=-inf */
+ if (hx<0) return (x-x)/zero; /* log(-#) = NaN */
+ k -= 54; x *= two54; /* subnormal number, scale up x */
+ GET_HIGH_WORD(hx,x);
+ }
+ if (hx >= 0x7ff00000) return x+x;
+ k += (hx>>20)-1023;
+ hx &= 0x000fffff;
+ i = (hx+0x95f64)&0x100000;
+ SET_HIGH_WORD(x,hx|(i^0x3ff00000)); /* normalize x or x/2 */
+ k += (i>>20);
+ f = x-1.0;
+ dk = (double)k;
+ if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */
+ if (f==zero)
+ return (dk);
+ R = f*f*(0.5-0.33333333333333333*f);
+ return (dk-(R-f)/ln2);
+ }
+ s = f/(2.0+f);
+ z = s*s;
+ i = hx-0x6147a;
+ w = z*z;
+ j = 0x6b851-hx;
+ t1= w*(Lg2+w*(Lg4+w*Lg6));
+ t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
+ i |= j;
+ R = t2+t1;
+ if(i>0) {
+ hfsq=0.5*f*f;
+ return (dk-(hfsq-s*(hfsq+R)-f)/ln2);
+ } else
+ return (dk-((s*(f-R))-f)/ln2);
+}
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