Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpf / get_ui.c

diff --git a/gmp/mpf/get_ui.c b/gmp/mpf/get_ui.c
new file mode 100644 (file)
index 0000000..0acaf94
--- /dev/null
+++ b/gmp/mpf/get_ui.c
@@ -0,0 +1,91 @@
+/* mpf_get_ui -- mpf to ulong conversion
+
+Copyright 2001, 2002, 2004 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 Lesser General Public License as published by
+the Free Software Foundation; either version 3 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+
+/* Any fraction bits are truncated, meaning simply discarded.
+
+   For values bigger than a ulong, the low bits are returned (the low
+   absolute value bits actually), like mpz_get_ui, but this isn't
+   documented.
+
+   Notice this is equivalent to mpz_set_f + mpz_get_ui.
+
+
+   Implementation:
+
+   The limb just above the radix point for us to extract is ptr[size-exp].
+
+   We need to check that the size-exp index falls in our available data
+   range, 0 to size-1 inclusive.  We test this without risk of an overflow
+   involving exp by requiring size>=exp (giving size-exp >= 0) and exp>0
+   (giving size-exp <= size-1).
+
+   Notice if size==0 there's no fetch, since of course size>=exp and exp>0
+   can only be true if size>0.  So there's no special handling for size==0,
+   it comes out as 0 the same as any other time we have no data at our
+   target index.
+
+   For nails, the second limb above the radix point is also required, this
+   is ptr[size-exp+1].
+
+   Again we need to check that size-exp+1 falls in our data range, 0 to
+   size-1 inclusive.  We test without risk of overflow by requiring
+   size+1>=exp (giving size-exp+1 >= 0) and exp>1 (giving size-exp+1 <=
+   size-1).
+
+   And again if size==0 these second fetch conditions are not satisfied
+   either since size+1>=exp and exp>1 are only true if size>0.
+
+   The code is arranged with exp>0 wrapping the exp>1 test since exp>1 is
+   mis-compiled by alpha gcc prior to version 3.4.  It re-writes it as
+   exp-1>0, which is incorrect when exp==MP_EXP_T_MIN.  By having exp>0
+   tested first we ensure MP_EXP_T_MIN doesn't reach exp>1.  */
+
+unsigned long
+mpf_get_ui (mpf_srcptr f)
+{
+  mp_size_t size;
+  mp_exp_t exp;
+  mp_srcptr fp;
+  mp_limb_t fl;
+
+  exp = EXP (f);
+  size = SIZ (f);
+  fp = PTR (f);
+
+  fl = 0;
+  if (exp > 0)
+    {
+      /* there are some limbs above the radix point */
+
+      size = ABS (size);
+      if (size >= exp)
+        fl = fp[size-exp];
+
+#if BITS_PER_ULONG > GMP_NUMB_BITS
+      if (exp > 1 && size+1 >= exp)
+        fl += (fp[size-exp+1] << GMP_NUMB_BITS);
+#endif
+    }
+
+  return (unsigned long) fl;
+}