Imported gcc-4.4.3

[msp430-gcc.git] / mpfr / extract.c

diff --git a/mpfr/extract.c b/mpfr/extract.c
new file mode 100644 (file)
index 0000000..4b0af37
--- /dev/null
+++ b/mpfr/extract.c
@@ -0,0 +1,55 @@
+/* mpfr_extract -- bit-extraction function for the binary splitting algorithm
+
+Copyright 2000, 2001, 2002, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+MA 02110-1301, USA. */
+
+#include "mpfr-impl.h"
+
+/* given 0 <= |p| < 1, this function extracts limbs of p and puts them in y.
+   It is mainly designed for the "binary splitting" algorithm.
+
+   More precisely, if B = 2^BITS_PER_MP_LIMB:
+   - for i=0, y = floor(p * B)
+   - for i>0, y = (p * B^(2^i)) mod B^(2^(i-1))
+ */
+
+void
+mpfr_extract (mpz_ptr y, mpfr_srcptr p, unsigned int i)
+{
+  unsigned long two_i = 1UL << i;
+  unsigned long two_i_2 = i ? two_i / 2 : 1;
+  mp_size_t size_p = MPFR_LIMB_SIZE (p);
+
+  /* as 0 <= |p| < 1, we don't have to care with infinities, NaN, ... */
+  MPFR_ASSERTD (!MPFR_IS_SINGULAR (p));
+
+  _mpz_realloc (y, two_i_2);
+  if ((mpfr_uexp_t) size_p < two_i)
+    {
+      MPN_ZERO (PTR(y), two_i_2);
+      if ((mpfr_uexp_t) size_p >= two_i_2)
+        MPN_COPY (PTR(y) + two_i - size_p, MPFR_MANT(p), size_p - two_i_2);
+    }
+  else
+    MPN_COPY (PTR(y), MPFR_MANT(p) + size_p - two_i, two_i_2);
+
+  MPN_NORMALIZE (PTR(y), two_i_2);
+  SIZ(y) = (MPFR_IS_NEG (p)) ? -two_i_2 : two_i_2;
+}