Initial revision

1 files changed, 57 insertions, 0 deletions

diff --git a/mpf/set_prc.c b/mpf/set_prc.c
new file mode 100644
index 000000000..10f2b0671
--- /dev/null
+++ b/mpf/set_prc.c
@@ -0,0 +1,57 @@
+/* mpf_set_prec(x) -- Change the precision of x.
+
+Copyright (C) 1993, 1994, 1995 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"
+
+void
+#if __STDC__
+mpf_set_prec (mpf_ptr x, unsigned long int prec_in_bits)
+#else
+mpf_set_prec (x, prec_in_bits)
+     mpf_ptr x;
+     unsigned long int prec_in_bits;
+#endif
+{
+  mp_size_t prec;
+  mp_size_t size = ABS (x->_mp_size);
+
+  prec = (MAX (53, prec_in_bits) + 2 * BITS_PER_MP_LIMB - 1)/BITS_PER_MP_LIMB;
+
+  /* We want the most significant limbs, so move the limbs down if we are
+     about to truncate the value.  */
+  if (size > prec + 1)
+    {
+      mp_size_t offset = size - (prec + 1);
+      mp_ptr xp = x->_mp_d;
+
+      MPN_COPY (xp, xp + offset, prec + 1);
+    }
+
+  x->_mp_d = (mp_ptr) (*_mp_reallocate_func)
+    (x->_mp_d,
+     (x->_mp_prec + 1) * BYTES_PER_MP_LIMB, (prec + 1) * BYTES_PER_MP_LIMB);
+  x->_mp_prec = prec;
+
+  /* If the precision decreased, truncate the number.  */
+  if (size > prec + 1)
+    x->_mp_size = x->_mp_size >= 0 ? (prec + 1) : -(prec + 1);
+}