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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_log10.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_log10.c')
| -rw-r--r-- | StdLib/LibC/Math/e_log10.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/StdLib/LibC/Math/e_log10.c b/StdLib/LibC/Math/e_log10.c new file mode 100644 index 0000000000..141dd6752a --- /dev/null +++ b/StdLib/LibC/Math/e_log10.c @@ -0,0 +1,106 @@ +/** @file
+ Compute the base 10 logrithm of x.
+
+ Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
+ This program and the accompanying materials are licensed and made available under
+ the terms and conditions of the BSD License that accompanies this distribution.
+ The full text of the license may be found at
+ http://opensource.org/licenses/bsd-license.
+
+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+ * ====================================================
+ * 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.
+ * ====================================================
+
+ e_log10.c 5.1 93/09/24
+ NetBSD: e_log10.c,v 1.12 2002/05/26 22:01:51 wiz Exp
+**/
+#include <LibConfig.h>
+#include <sys/EfiCdefs.h>
+
+/* __ieee754_log10(x)
+ * Return the base 10 logarithm of x
+ *
+ * Method :
+ * Let log10_2hi = leading 40 bits of log10(2) and
+ * log10_2lo = log10(2) - log10_2hi,
+ * ivln10 = 1/log(10) rounded.
+ * Then
+ * n = ilogb(x),
+ * if(n<0) n = n+1;
+ * x = scalbn(x,-n);
+ * log10(x) := n*log10_2hi + (n*log10_2lo + ivln10*log(x))
+ *
+ * Note 1:
+ * To guarantee log10(10**n)=n, where 10**n is normal, the rounding
+ * mode must set to Round-to-Nearest.
+ * Note 2:
+ * [1/log(10)] rounded to 53 bits has error .198 ulps;
+ * log10 is monotonic at all binary break points.
+ *
+ * Special cases:
+ * log10(x) is NaN with signal if x < 0;
+ * log10(+INF) is +INF with no signal; log10(0) is -INF with signal;
+ * log10(NaN) is that NaN with no signal;
+ * log10(10**N) = N for N=0,1,...,22.
+ *
+ * Constants:
+ * The hexadecimal values are the intended ones for the following constants.
+ * The decimal values may be used, provided that the compiler will convert
+ * from decimal to binary accurately enough to produce the hexadecimal values
+ * shown.
+ */
+
+#include "math.h"
+#include "math_private.h"
+#include <errno.h>
+
+#if defined(_MSC_VER) /* Handle Microsoft VC++ compiler specifics. */
+ // potential divide by 0 -- near line 80, (x-x)/zero is on purpose
+ #pragma warning ( disable : 4723 )
+#endif
+
+static const double
+two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+ivln10 = 4.34294481903251816668e-01, /* 0x3FDBCB7B, 0x1526E50E */
+log10_2hi = 3.01029995663611771306e-01, /* 0x3FD34413, 0x509F6000 */
+log10_2lo = 3.69423907715893078616e-13; /* 0x3D59FEF3, 0x11F12B36 */
+
+static const double zero = 0.0;
+
+double
+__ieee754_log10(double x)
+{
+ double y,z;
+ int32_t i,k,hx;
+ 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) {
+ errno = EDOM;
+ 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;
+ i = ((u_int32_t)k&0x80000000)>>31;
+ hx = (hx&0x000fffff)|((0x3ff-i)<<20);
+ y = (double)(k+i);
+ SET_HIGH_WORD(x,hx);
+ z = y*log10_2lo + ivln10*__ieee754_log(x);
+ return z+y*log10_2hi;
+}
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