Imported gcc-4.4.3

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

diff --git a/mpfr/get_z_exp.c b/mpfr/get_z_exp.c
new file mode 100644 (file)
index 0000000..fba973b
--- /dev/null
+++ b/mpfr/get_z_exp.c
@@ -0,0 +1,72 @@
+/* mpfr_get_z_exp -- get a multiple-precision integer and an exponent
+                     from a floating-point number
+
+Copyright 2000, 2001, 2002, 2003, 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"
+
+/* puts the mantissa of f into z, and returns 'exp' such that f = z * 2^exp
+ *
+ * 0 doesn't have an exponent, therefore the returned exponent in this case
+ * isn't really important. We choose to return __gmpfr_emin because
+ *   1) it is in the exponent range [__gmpfr_emin,__gmpfr_emax],
+ *   2) the smaller a number is (in absolute value), the smaller its
+ *      exponent is. In other words, the f -> exp function is monotonous
+ *      on nonnegative numbers.
+ * Note that this is different from the C function frexp().
+ */
+
+mp_exp_t
+mpfr_get_z_exp (mpz_ptr z, mpfr_srcptr f)
+{
+  mp_size_t fn;
+  int sh;
+
+  MPFR_ASSERTD (MPFR_IS_FP (f));
+
+  if (MPFR_UNLIKELY (MPFR_IS_ZERO (f)))
+    {
+      mpz_set_ui (z, 0);
+      return __gmpfr_emin;
+    }
+
+  fn = MPFR_LIMB_SIZE(f);
+
+  /* check whether allocated space for z is enough */
+  if (MPFR_UNLIKELY (ALLOC (z) < fn))
+    MPZ_REALLOC (z, fn);
+
+  MPFR_UNSIGNED_MINUS_MODULO (sh, MPFR_PREC (f));
+  if (MPFR_LIKELY (sh))
+    mpn_rshift (PTR (z), MPFR_MANT (f), fn, sh);
+  else
+    MPN_COPY (PTR (z), MPFR_MANT (f), fn);
+
+  SIZ(z) = MPFR_IS_NEG (f) ? -fn : fn;
+
+  /* Test if the result is representable. Later, we could choose
+     to return MPFR_EXP_MIN if it isn't, or perhaps MPFR_EXP_MAX
+     to signal an error. The mantissa would still be meaningful. */
+  MPFR_ASSERTD ((mp_exp_unsigned_t) MPFR_GET_EXP (f) - MPFR_EXP_MIN
+                >= (mp_exp_unsigned_t) MPFR_PREC(f));
+
+  return MPFR_GET_EXP (f) - MPFR_PREC (f);
+}