Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 133 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/ieee754/dbl-64/e_log2.c b/REORG.TODO/sysdeps/ieee754/dbl-64/e_log2.c
new file mode 100644
index 0000000000..5af68d8ecc
--- /dev/null
+++ b/REORG.TODO/sysdeps/ieee754/dbl-64/e_log2.c
@@ -0,0 +1,133 @@
+/* Adapted for log2 by Ulrich Drepper <drepper@cygnus.com>.  */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/* __ieee754_log2(x)
+ * Return the logarithm to base 2 of x
+ *
+ * Method :
+ *   1. Argument Reduction: find k and f such that
+ *			x = 2^k * (1+f),
+ *	   where  sqrt(2)/2 < 1+f < sqrt(2) .
+ *
+ *   2. Approximation of log(1+f).
+ *	Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
+ *		 = 2s + 2/3 s**3 + 2/5 s**5 + .....,
+ *		 = 2s + s*R
+ *      We use a special Reme algorithm on [0,0.1716] to generate
+ *	a polynomial of degree 14 to approximate R The maximum error
+ *	of this polynomial approximation is bounded by 2**-58.45. In
+ *	other words,
+ *			2      4      6      8      10      12      14
+ *	    R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s  +Lg6*s  +Lg7*s
+ *	(the values of Lg1 to Lg7 are listed in the program)
+ *	and
+ *	    |      2          14          |     -58.45
+ *	    | Lg1*s +...+Lg7*s    -  R(z) | <= 2
+ *	    |                             |
+ *	Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
+ *	In order to guarantee error in log below 1ulp, we compute log
+ *	by
+ *		log(1+f) = f - s*(f - R)	(if f is not too large)
+ *		log(1+f) = f - (hfsq - s*(hfsq+R)).	(better accuracy)
+ *
+ *	3. Finally,  log(x) = k + log(1+f).
+ *			    = k+(f-(hfsq-(s*(hfsq+R))))
+ *
+ * Special cases:
+ *	log2(x) is NaN with signal if x < 0 (including -INF) ;
+ *	log2(+INF) is +INF; log(0) is -INF with signal;
+ *	log2(NaN) is that NaN with no signal.
+ *
+ * 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 <fix-int-fp-convert-zero.h>
+
+static const double ln2 = 0.69314718055994530942;
+static const double two54 = 1.80143985094819840000e+16; /* 43500000 00000000 */
+static const double Lg1 = 6.666666666666735130e-01;     /* 3FE55555 55555593 */
+static const double Lg2 = 3.999999999940941908e-01;     /* 3FD99999 9997FA04 */
+static const double Lg3 = 2.857142874366239149e-01;     /* 3FD24924 94229359 */
+static const double Lg4 = 2.222219843214978396e-01;     /* 3FCC71C5 1D8E78AF */
+static const double Lg5 = 1.818357216161805012e-01;     /* 3FC74664 96CB03DE */
+static const double Lg6 = 1.531383769920937332e-01;     /* 3FC39A09 D078C69F */
+static const double 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 (__glibc_unlikely (((hx & 0x7fffffff) | lx) == 0))
+	return -two54 / __fabs (x);        /* log(+-0)=-inf */
+      if (__glibc_unlikely (hx < 0))
+	return (x - x) / (x - x);       /* log(-#) = NaN */
+      k -= 54;
+      x *= two54;               /* subnormal number, scale up x */
+      GET_HIGH_WORD (hx, x);
+    }
+  if (__glibc_unlikely (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);
+  dk = (double) k;
+  f = x - 1.0;
+  if ((0x000fffff & (2 + hx)) < 3)
+    {                           /* |f| < 2**-20 */
+      if (f == zero)
+	{
+	  if (FIX_INT_FP_CONVERT_ZERO && dk == 0.0)
+	    dk = 0.0;
+	  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;
+    }
+}
+
+strong_alias (__ieee754_log2, __log2_finite)