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, 120 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/i386/ldbl2mpn.c b/REORG.TODO/sysdeps/i386/ldbl2mpn.c
new file mode 100644
index 0000000000..076be0ae7e
--- /dev/null
+++ b/REORG.TODO/sysdeps/i386/ldbl2mpn.c
@@ -0,0 +1,120 @@
+/* Copyright (C) 1995-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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 "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+#include <ieee754.h>
+#include <float.h>
+#include <stdlib.h>
+
+/* Convert a `long double' in IEEE854 standard double-precision format to a
+   multi-precision integer representing the significand scaled up by its
+   number of bits (64 for long double) and an integral power of two
+   (MPN frexpl). */
+
+mp_size_t
+__mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
+			   int *expt, int *is_neg,
+			   long double value)
+{
+  union ieee854_long_double u;
+  u.d = value;
+
+  *is_neg = u.ieee.negative;
+  *expt = (int) u.ieee.exponent - IEEE854_LONG_DOUBLE_BIAS;
+
+#if BITS_PER_MP_LIMB == 32
+  res_ptr[0] = u.ieee.mantissa1; /* Low-order 32 bits of fraction.  */
+  res_ptr[1] = u.ieee.mantissa0; /* High-order 32 bits.  */
+  #define N 2
+#elif BITS_PER_MP_LIMB == 64
+  /* Hopefully the compiler will combine the two bitfield extracts
+     and this composition into just the original quadword extract.  */
+  res_ptr[0] = ((mp_limb_t) u.ieee.mantissa0 << 32) | u.ieee.mantissa1;
+  #define N 1
+#else
+  #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
+#endif
+
+  if (u.ieee.exponent == 0)
+    {
+      /* A biased exponent of zero is a special case.
+	 Either it is a zero or it is a denormal number.  */
+      if (res_ptr[0] == 0 && res_ptr[N - 1] == 0) /* Assumes N<=2.  */
+	/* It's zero.  */
+	*expt = 0;
+      else
+	{
+	  /* It is a denormal number, meaning it has no implicit leading
+	     one bit, and its exponent is in fact the format minimum.  */
+	  int cnt;
+
+	  /* One problem with Intel's 80-bit format is that the explicit
+	     leading one in the normalized representation has to be zero
+	     for denormalized number.  If it is one, the number is according
+	     to Intel's specification an invalid number.  We make the
+	     representation unique by explicitly clearing this bit.  */
+	  res_ptr[N - 1] &= ~((mp_limb_t) 1 << ((LDBL_MANT_DIG - 1) % BITS_PER_MP_LIMB));
+
+	  if (res_ptr[N - 1] != 0)
+	    {
+	      count_leading_zeros (cnt, res_ptr[N - 1]);
+	      if (cnt != 0)
+		{
+#if N == 2
+		  res_ptr[N - 1] = res_ptr[N - 1] << cnt
+				   | (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt));
+		  res_ptr[0] <<= cnt;
+#else
+		  res_ptr[N - 1] <<= cnt;
+#endif
+		}
+	      *expt = LDBL_MIN_EXP - 1 - cnt;
+	    }
+	  else if (res_ptr[0] != 0)
+	    {
+	      count_leading_zeros (cnt, res_ptr[0]);
+	      res_ptr[N - 1] = res_ptr[0] << cnt;
+	      res_ptr[0] = 0;
+	      *expt = LDBL_MIN_EXP - 1 - BITS_PER_MP_LIMB - cnt;
+	    }
+	  else
+	    {
+	      /* This is the special case of the pseudo denormal number
+		 with only the implicit leading bit set.  The value is
+		 in fact a normal number and so we have to treat this
+		 case differently.  */
+#if N == 2
+	      res_ptr[N - 1] = 0x80000000ul;
+#else
+	      res_ptr[0] = 0x8000000000000000ul;
+#endif
+	      *expt = LDBL_MIN_EXP - 1;
+	    }
+	}
+    }
+  else if (u.ieee.exponent < 0x7fff
+#if N == 2
+	   && res_ptr[0] == 0
+#endif
+	   && res_ptr[N - 1] == 0)
+    /* Pseudo zero.  */
+    *expt = 0;
+
+  return N;
+}