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, 196 insertions, 0 deletions

diff --git a/REORG.TODO/math/atest-exp.c b/REORG.TODO/math/atest-exp.c
new file mode 100644
index 0000000000..6029ae1fdf
--- /dev/null
+++ b/REORG.TODO/math/atest-exp.c
@@ -0,0 +1,196 @@
+/* Copyright (C) 1997-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Geoffrey Keating <Geoff.Keating@anu.edu.au>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <math.h>
+#include <gmp.h>
+#include <string.h>
+#include <limits.h>
+#include <assert.h>
+
+#define PRINT_ERRORS 0
+
+#define TOL 80
+#define N2 17
+#define FRAC (32*4)
+
+#define mpbpl (CHAR_BIT * sizeof (mp_limb_t))
+#define SZ (FRAC / mpbpl + 1)
+typedef mp_limb_t mp1[SZ], mp2[SZ * 2];
+
+/* This string has 101 hex digits.  */
+static const char exp1[102] = "2" /* point */
+"b7e151628aed2a6abf7158809cf4f3c762e7160f38b4da56a7"
+"84d9045190cfef324e7738926cfbe5f4bf8d8d8c31d763da07";
+static const char hexdig[] = "0123456789abcdef";
+
+static void
+print_mpn_hex (const mp_limb_t *x, unsigned size)
+{
+   char value[size + 1];
+   unsigned i;
+   const unsigned final = (size * 4 > SZ * mpbpl) ? SZ * mpbpl / 4 : size;
+
+   memset (value, '0', size);
+
+   for (i = 0; i < final ; i++)
+     value[size - 1 - i] = hexdig[x[i * 4 / mpbpl] >> (i * 4) % mpbpl & 0xf];
+
+   value[size] = '\0';
+   fputs (value, stdout);
+}
+
+static void
+exp_mpn (mp1 ex, mp1 x)
+{
+   unsigned n;
+   mp1 xp;
+   mp2 tmp;
+   mp_limb_t chk __attribute__ ((unused));
+   mp1 tol;
+
+   memset (xp, 0, sizeof (mp1));
+   memset (ex, 0, sizeof (mp1));
+   xp[FRAC / mpbpl] = (mp_limb_t)1 << FRAC % mpbpl;
+   memset (tol,0, sizeof (mp1));
+   tol[(FRAC - TOL) / mpbpl] = (mp_limb_t)1 << (FRAC - TOL) % mpbpl;
+
+   n = 0;
+
+   do
+     {
+       /* Calculate sum(x^n/n!) until the next term is sufficiently small.  */
+
+       mpn_mul_n (tmp, xp, x, SZ);
+       assert (tmp[SZ * 2 - 1] == 0);
+       if (n > 0)
+	 mpn_divmod_1 (xp, tmp + FRAC / mpbpl, SZ, n);
+       chk = mpn_add_n (ex, ex, xp, SZ);
+       assert (chk == 0);
+       n++;
+       assert (n < 80); /* Catch too-high TOL.  */
+     }
+   while (n < 10 || mpn_cmp (xp, tol, SZ) >= 0);
+}
+
+static int
+mpn_bitsize(const mp_limb_t *SRC_PTR, mp_size_t SIZE)
+{
+   int i, j;
+   for (i = SIZE - 1; i > 0; i--)
+     if (SRC_PTR[i] != 0)
+       break;
+   for (j = mpbpl - 1; j >= 0; j--)
+     if ((SRC_PTR[i] & (mp_limb_t)1 << j) != 0)
+       break;
+
+   return i * mpbpl + j;
+}
+
+static int
+do_test (void)
+{
+   mp1 ex, x, xt, e2, e3;
+   int i;
+   int errors = 0;
+   int failures = 0;
+   mp1 maxerror;
+   int maxerror_s = 0;
+   const double sf = pow (2, mpbpl);
+
+   /* assert (mpbpl == mp_bits_per_limb); */
+   assert (FRAC / mpbpl * mpbpl == FRAC);
+
+   memset (maxerror, 0, sizeof (mp1));
+   memset (xt, 0, sizeof (mp1));
+   xt[(FRAC - N2) / mpbpl] = (mp_limb_t)1 << (FRAC - N2) % mpbpl;
+
+   for (i = 0; i < 1 << N2; i++)
+   {
+      int e2s, e3s, j;
+      double de2;
+
+      mpn_mul_1 (x,xt,SZ,i);
+      exp_mpn (ex, x);
+      de2 = exp (i / (double) (1 << N2));
+      for (j = SZ-1; j >= 0; j--)
+	{
+	  e2[j] = (mp_limb_t) de2;
+	  de2 = (de2 - e2[j]) * sf;
+	}
+      if (mpn_cmp (ex,e2,SZ) >= 0)
+	mpn_sub_n (e3,ex,e2,SZ);
+      else
+	mpn_sub_n (e3,e2,ex,SZ);
+
+      e2s = mpn_bitsize (e2,SZ);
+      e3s = mpn_bitsize (e3,SZ);
+      if (e3s >= 0 && e2s - e3s < 54)
+	{
+#if PRINT_ERRORS
+	  printf ("%06x ", i * (0x100000 / (1 << N2)));
+	  print_mpn_hex (ex, (FRAC / 4) + 1);
+	  fputs ("\n       ",stdout);
+	  print_mpn_hex (e2, (FRAC / 4) + 1);
+	  printf ("\n %c     ",
+		  e2s - e3s < 54 ? e2s - e3s == 53 ? 'e' : 'F' : 'P');
+	  print_mpn_hex (e3, (FRAC / 4) + 1);
+	  putchar ('\n');
+#endif
+	 errors += (e2s - e3s == 53);
+	 failures += (e2s - e3s < 53);
+	}
+      if (e3s >= maxerror_s
+	  && mpn_cmp (e3, maxerror, SZ) > 0)
+	{
+	  memcpy (maxerror, e3, sizeof (mp1));
+	  maxerror_s = e3s;
+	}
+   }
+
+   /* Check exp_mpn against precomputed value of exp(1).  */
+   memset (x, '\0', sizeof (mp1));
+   x[FRAC / mpbpl] = (mp_limb_t)1 << FRAC % mpbpl;
+   exp_mpn (ex, x);
+
+   memset (e2, '\0', sizeof (mp1));
+   for (i = -1; i < 100 && i < FRAC / 4; i++)
+     e2[(FRAC - i * 4 - 4) / mpbpl] |= ((mp_limb_t) (strchr (hexdig,
+							     exp1[i + 1])
+						     - hexdig)
+ 					<< (FRAC - i * 4 - 4) % mpbpl);
+
+   if (mpn_cmp (ex, e2, SZ) >= 0)
+     mpn_sub_n (e3, ex, e2, SZ);
+   else
+     mpn_sub_n (e3, e2, ex, SZ);
+
+   printf ("%d failures; %d errors; error rate %0.2f%%\n", failures, errors,
+	   errors * 100.0 / (double) (1 << N2));
+   fputs ("maximum error:   ", stdout);
+   print_mpn_hex (maxerror, (FRAC / 4) + 1);
+   fputs ("\nerror in exp(1): ", stdout);
+   print_mpn_hex (e3, (FRAC / 4) + 1);
+   putchar ('\n');
+
+   return failures == 0 ? 0 : 1;
+}
+
+#define TIMEOUT 200
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"