Renamed from extract-double.c.

(MP_BASE_AS_DOUBLE): Don't redefine here.

1 files changed, 158 insertions, 0 deletions

diff --git a/extract-dbl.c b/extract-dbl.c
new file mode 100644
index 000000000..d86871a94
--- /dev/null
+++ b/extract-dbl.c
@@ -0,0 +1,158 @@
+/* __gmp_extract_double -- convert from double to array of mp_limb_t.
+
+Copyright (C) 1996 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Library General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at your
+option) any later version.
+
+The GNU MP 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 Library General Public
+License for more details.
+
+You should have received a copy of the GNU Library General Public License
+along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+#ifdef XDEBUG
+#undef _GMP_IEEE_FLOATS
+#endif
+
+#ifndef _GMP_IEEE_FLOATS
+#define _GMP_IEEE_FLOATS 0
+#endif
+
+/* Extract a non-negative double in d.  */
+
+int
+#if __STDC__
+__gmp_extract_double (mp_ptr rp, double d)
+#else
+__gmp_extract_double (rp, d)
+     mp_ptr rp;
+     double d;
+#endif
+{
+  long exp;
+  unsigned sc;
+  mp_limb_t manh, manl;
+
+  /* BUGS
+
+     1. Should handle Inf and NaN in IEEE specific code.
+     2. Handle Inf and NaN also in default code, to avoid hangs.
+     3. Generalize to handle all BITS_PER_MP_LIMB >= 32.
+     4. This lits is incomplete and misspelled.
+   */
+
+  if (d == 0.0)
+    {
+      rp[0] = 0;
+      rp[1] = 0;
+#if BITS_PER_MP_LIMB == 32
+      rp[2] = 0;
+#endif
+      return 0;
+    }
+
+#if _GMP_IEEE_FLOATS
+  {
+    union ieee_double_extract x;
+    x.d = d;
+
+    exp = x.s.exp;
+    sc = (unsigned) (exp + 2) % BITS_PER_MP_LIMB;
+#if BITS_PER_MP_LIMB == 64
+    manl = (((mp_limb_t) 1 << 63)
+	    | ((mp_limb_t) x.s.manh << 43) | ((mp_limb_t) x.s.manl << 11));
+#else
+    manh = ((mp_limb_t) 1 << 31) | (x.s.manh << 11) | (x.s.manl >> 21);
+    manl = x.s.manl << 11;
+#endif
+  }
+#else
+  {
+    /* Unknown (or known to be non-IEEE) double format.  */
+    exp = 0;
+    if (d >= 1.0)
+      {
+	if (d * 0.5 == d)
+	  abort ();
+
+	while (d >= 32768.0)
+	  {
+	    d *= (1.0 / 65536.0);
+	    exp += 16;
+	  }
+	while (d >= 1.0)
+	  {
+	    d *= 0.5;
+	    exp += 1;
+	  }
+      }
+    else if (d < 0.5)
+      {
+	while (d < (1.0 / 65536.0))
+	  {
+	    d *=  65536.0;
+	    exp -= 16;
+	  }
+	while (d < 0.5)
+	  {
+	    d *= 2.0;
+	    exp -= 1;
+	  }
+      }
+
+    sc = (unsigned) exp % BITS_PER_MP_LIMB;
+
+    d *= MP_BASE_AS_DOUBLE;
+#if BITS_PER_MP_LIMB == 64
+    manl = d;
+#else
+    manh = d;
+    manl = (d - manh) * MP_BASE_AS_DOUBLE;
+#endif
+
+    exp += 1022;
+  }
+#endif
+
+  exp = (unsigned) (exp + 1) / BITS_PER_MP_LIMB - 1024 / BITS_PER_MP_LIMB + 1;
+
+#if BITS_PER_MP_LIMB == 64
+  if (sc != 0)
+    {
+      rp[1] = manl >> (BITS_PER_MP_LIMB - sc);
+      rp[0] = manl << sc;
+    }
+  else
+    {
+      rp[1] = manl;
+      rp[0] = 0;
+    }
+#else
+  if (sc != 0)
+    {
+      rp[2] = manh >> (BITS_PER_MP_LIMB - sc);
+      rp[1] = (manl >> (BITS_PER_MP_LIMB - sc)) | (manh << sc);
+      rp[0] = manl << sc;
+    }
+  else
+    {
+      rp[2] = manh;
+      rp[1] = manl;
+      rp[0] = 0;
+    }
+#endif
+
+  return exp;
+}