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, 228 insertions, 0 deletions

diff --git a/REORG.TODO/math/atest-exp2.c b/REORG.TODO/math/atest-exp2.c
new file mode 100644
index 0000000000..397e7f881d
--- /dev/null
+++ b/REORG.TODO/math/atest-exp2.c
@@ -0,0 +1,228 @@
+/* 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>
+#include <stdlib.h>
+
+#define PRINT_ERRORS 0
+
+#define TOL 80
+#define N2 18
+#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];
+
+#if BITS_PER_MP_LIMB == 64
+# define LIMB64(L, H) 0x ## H ## L
+#elif BITS_PER_MP_LIMB == 32
+# define LIMB64(L, H) 0x ## L, 0x ## H
+#else
+# error
+#endif
+
+/* Once upon a time these constants were generated to 400 bits.
+   We only need FRAC bits (128) at present, but we retain 384 bits
+   in the text Just In Case.  */
+#define CONSTSZ(INT, F1, F2, F3, F4, F5, F6, F7, F8, F9, Fa, Fb, Fc) \
+	LIMB64(F4, F3), LIMB64(F2, F1), INT
+
+static const mp1 mp_exp1 = {
+  CONSTSZ (2, b7e15162, 8aed2a6a, bf715880, 9cf4f3c7, 62e7160f, 38b4da56,
+           a784d904, 5190cfef, 324e7738, 926cfbe5, f4bf8d8d, 8c31d763)
+};
+
+static const mp1 mp_log2 = {
+  CONSTSZ (0, b17217f7, d1cf79ab, c9e3b398, 03f2f6af, 40f34326, 7298b62d,
+           8a0d175b, 8baafa2b, e7b87620, 6debac98, 559552fb, 4afa1b10)
+};
+
+static void
+print_mpn_fp (const mp_limb_t *x, unsigned int dp, unsigned int base)
+{
+   static const char hexdig[16] = "0123456789abcdef";
+   unsigned int i;
+   mp1 tx;
+
+   memcpy (tx, x, sizeof (mp1));
+   if (base == 16)
+     fputs ("0x", stdout);
+   assert (x[SZ-1] < base);
+   fputc (hexdig[x[SZ - 1]], stdout);
+   fputc ('.', stdout);
+   for (i = 0; i < dp; i++)
+     {
+       tx[SZ - 1] = 0;
+       mpn_mul_1 (tx, tx, SZ, base);
+       assert (tx[SZ - 1] < base);
+       fputc (hexdig[tx[SZ - 1]], stdout);
+     }
+}
+
+/* Compute e^x.  */
+static void
+exp_mpn (mp1 ex, mp1 x)
+{
+   unsigned int 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);
+}
+
+/* Calculate 2^x.  */
+static void
+exp2_mpn (mp1 ex, mp1 x)
+{
+  mp2 tmp;
+  mpn_mul_n (tmp, x, mp_log2, SZ);
+  assert(tmp[SZ * 2 - 1] == 0);
+  exp_mpn (ex, tmp + FRAC / mpbpl);
+}
+
+
+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);
+      exp2_mpn (ex, x);
+      de2 = exp2 (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_fp (ex, (FRAC / 4) + 1, 16);
+	  putchar ('\n');
+	  fputs ("       ",stdout);
+	  print_mpn_fp (e2, (FRAC / 4) + 1, 16);
+	  putchar ('\n');
+	  printf (" %c     ",
+		  e2s - e3s < 54 ? e2s - e3s == 53 ? 'e' : 'F' : 'P');
+	  print_mpn_fp (e3, (FRAC / 4) + 1, 16);
+	  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);
+  if (mpn_cmp (ex, mp_exp1, SZ) >= 0)
+    mpn_sub_n (e3, ex, mp_exp1, SZ);
+  else
+    mpn_sub_n (e3, mp_exp1, 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_fp (maxerror, (FRAC / 4) + 1, 16);
+  putchar ('\n');
+  fputs ("error in exp(1): ", stdout);
+  print_mpn_fp (e3, (FRAC / 4) + 1, 16);
+  putchar ('\n');
+
+  return failures == 0 ? 0 : 1;
+}
+
+#define TIMEOUT 300
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"