New function mpf_get_d.

1 files changed, 56 insertions, 0 deletions

diff --git a/mpf/get_d.c b/mpf/get_d.c
new file mode 100644
index 000000000..8fa6173a9
--- /dev/null
+++ b/mpf/get_d.c
@@ -0,0 +1,56 @@
+/* double mpf_get_d (mpf_t src) -- Return the double approximation to SRC.
+
+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"
+
+double scal2 ();
+
+double
+#if __STDC__
+mpf_get_d (mpf_srcptr src)
+#else
+mpf_get_d (src)
+     mpf_srcptr src;
+#endif
+{
+  double res;
+  mp_size_t size, i, n_limbs_to_use;
+  int negative;
+  mp_ptr qp;
+
+  size = SIZ(src);
+  if (size == 0)
+    return 0.0;
+
+  negative = size < 0;
+  size = ABS (size);
+  qp = PTR(src);
+
+  res = qp[size - 1];
+  n_limbs_to_use = MIN (LIMBS_PER_DOUBLE, size);
+  for (i = 2; i <= n_limbs_to_use; i++)
+    res = res * MP_BASE_AS_DOUBLE + qp[size - i];
+
+  res = scal2 (res, (EXP(src) - n_limbs_to_use) * BITS_PER_MP_LIMB);
+
+  return negative ? -res : res;
+}