Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpq / md_2exp.c

diff --git a/gmp/mpq/md_2exp.c b/gmp/mpq/md_2exp.c
new file mode 100644 (file)
index 0000000..87eba75
--- /dev/null
+++ b/gmp/mpq/md_2exp.c
@@ -0,0 +1,103 @@
+/* mpq_mul_2exp, mpq_div_2exp - multiply or divide by 2^N */
+
+/*
+Copyright 2000, 2002 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"
+#include "longlong.h"
+
+
+/* The multiplier/divisor "n", representing 2^n, is applied by right shifting
+   "r" until it's odd (if it isn't already), and left shifting "l" for the
+   rest. */
+
+static void
+mord_2exp (mpz_ptr ldst, mpz_ptr rdst, mpz_srcptr lsrc, mpz_srcptr rsrc,
+           unsigned long n)
+{
+  mp_size_t  rsrc_size = SIZ(rsrc);
+  mp_size_t  len = ABS (rsrc_size);
+  mp_ptr     rsrc_ptr = PTR(rsrc);
+  mp_ptr     p, rdst_ptr;
+  mp_limb_t  plow;
+
+  p = rsrc_ptr;
+  plow = *p;
+  while (n >= GMP_NUMB_BITS && plow == 0)
+    {
+      n -= GMP_NUMB_BITS;
+      p++;
+      plow = *p;
+    }
+
+  /* no realloc here if rsrc==rdst, so p and rsrc_ptr remain valid */
+  len -= (p - rsrc_ptr);
+  MPZ_REALLOC (rdst, len);
+  rdst_ptr = PTR(rdst);
+
+  if ((plow & 1) || n == 0)
+    {
+      /* need DECR when src==dst */
+      if (p != rdst_ptr)
+        MPN_COPY_DECR (rdst_ptr, p, len);
+    }
+  else
+    {
+      unsigned long  shift;
+      if (plow == 0)
+        shift = n;
+      else
+        {
+          count_trailing_zeros (shift, plow);
+          shift = MIN (shift, n);
+        }
+      mpn_rshift (rdst_ptr, p, len, shift);
+      len -= (rdst_ptr[len-1] == 0);
+      n -= shift;
+    }
+  SIZ(rdst) = (rsrc_size >= 0) ? len : -len;
+
+  if (n)
+    mpz_mul_2exp (ldst, lsrc, n);
+  else if (ldst != lsrc)
+    mpz_set (ldst, lsrc);
+}
+
+
+void
+mpq_mul_2exp (mpq_ptr dst, mpq_srcptr src, unsigned long n)
+{
+  mord_2exp (mpq_numref (dst), mpq_denref (dst),
+             mpq_numref (src), mpq_denref (src), n);
+}
+
+void
+mpq_div_2exp (mpq_ptr dst, mpq_srcptr src, unsigned long n)
+{
+  if (SIZ (mpq_numref(src)) == 0)
+    {
+      dst->_mp_num._mp_size = 0;
+      dst->_mp_den._mp_size = 1;
+      dst->_mp_den._mp_d[0] = 1;
+      return;
+    }
+
+  mord_2exp (mpq_denref (dst), mpq_numref (dst),
+             mpq_denref (src), mpq_numref (src), n);
+}