Imported gcc-4.4.3

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

diff --git a/gmp/mpf/get_si.c b/gmp/mpf/get_si.c
new file mode 100644 (file)
index 0000000..a0beb2c
--- /dev/null
+++ b/gmp/mpf/get_si.c
@@ -0,0 +1,76 @@
+/* mpf_get_si -- mpf to long 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 long, the low bits are returned, like
+   mpz_get_si, but this isn't documented.
+
+   Notice this is equivalent to mpz_set_f + mpz_get_si.
+
+
+   Implementation:
+
+   fl is established in basically the same way as for mpf_get_ui, see that
+   code for explanations of the conditions.
+
+   However unlike mpf_get_ui we need an explicit return 0 for exp<=0.  When
+   f is a negative fraction (ie. size<0 and exp<=0) we can't let fl==0 go
+   through to the zany final "~ ((fl - 1) & LONG_MAX)", that would give
+   -0x80000000 instead of the desired 0.  */
+
+long
+mpf_get_si (mpf_srcptr f)
+{
+  mp_exp_t exp;
+  mp_size_t size, abs_size;
+  mp_srcptr fp;
+  mp_limb_t fl;
+
+  exp = EXP (f);
+  size = SIZ (f);
+  fp = PTR (f);
+
+  /* fraction alone truncates to zero
+     this also covers zero, since we have exp==0 for zero */
+  if (exp <= 0)
+    return 0L;
+
+  /* there are some limbs above the radix point */
+
+  fl = 0;
+  abs_size = ABS (size);
+  if (abs_size >= exp)
+    fl = fp[abs_size-exp];
+
+#if BITS_PER_ULONG > GMP_NUMB_BITS
+  if (exp > 1 && abs_size+1 >= exp)
+    fl |= fp[abs_size - exp + 1] << GMP_NUMB_BITS;
+#endif
+
+  if (size > 0)
+    return fl & LONG_MAX;
+  else
+    /* this form necessary to correctly handle -0x80..00 */
+    return ~ ((fl - 1) & LONG_MAX);
+}