Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpn / generic / dc_bdiv_q.c

diff --git a/gmp/mpn/generic/dc_bdiv_q.c b/gmp/mpn/generic/dc_bdiv_q.c
new file mode 100644 (file)
index 0000000..9a43d18
--- /dev/null
+++ b/gmp/mpn/generic/dc_bdiv_q.c
@@ -0,0 +1,137 @@
+/* mpn_dc_bdiv_q -- divide-and-conquer Hensel division with precomputed
+   inverse, returning quotient.
+
+   Contributed to the GNU project by Niels Möller and Torbjörn Granlund.
+
+   THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH A MUTABLE INTERFACE.  IT IS
+   ONLY SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES.  IN FACT, IT IS
+   ALMOST GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GMP
+   RELEASE.
+
+Copyright 2006, 2007 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"
+
+
+/* Computes Q = N / D mod B^n, destroys N. */
+
+mp_size_t
+mpn_dc_bdiv_q_n_itch (mp_size_t n)
+{
+  /* NOTE: Depends om mullow_n interface */
+  return n;
+}
+
+void
+mpn_dc_bdiv_q_n (mp_ptr qp,
+                mp_ptr np, mp_srcptr dp, mp_size_t n,
+                mp_limb_t dinv, mp_ptr tp)
+{
+  while (ABOVE_THRESHOLD (n, DC_BDIV_Q_THRESHOLD))
+    {
+      mp_limb_t l, h;
+      mp_limb_t cy;
+
+      l = n >> 1;
+      h = n - l;
+
+      cy = mpn_dc_bdiv_qr_n (qp, np, dp, l, dinv, tp);
+
+      mpn_mullow_n (tp, qp, dp + h, l);
+      mpn_sub_n (np + h, np + h, tp, l);
+
+      if (l < h)
+       {
+         cy += mpn_submul_1 (np + l, qp, l, dp[l]);
+         np[n - 1] -= cy;
+       }
+      qp += l;
+      np += l;
+      n -= l;
+    }
+  mpn_sb_bdiv_q (qp, np, n, dp, n, dinv);
+}
+
+void
+mpn_dc_bdiv_q (mp_ptr qp,
+              mp_ptr np, mp_size_t nn,
+              mp_srcptr dp, mp_size_t dn,
+              mp_limb_t dinv)
+{
+  mp_size_t qn;
+  mp_limb_t cy;
+  mp_ptr tp;
+  TMP_DECL;
+
+  TMP_MARK;
+
+  tp = TMP_SALLOC_LIMBS (dn);
+
+  qn = nn;
+
+  if (qn > dn)
+    {
+      /* Reduce qn mod dn in a super-efficient manner.  */
+      do
+       qn -= dn;
+      while (qn > dn);
+
+      /* Perform the typically smaller block first.  */
+      if (BELOW_THRESHOLD (qn, DC_BDIV_QR_THRESHOLD))
+       cy = mpn_sb_bdiv_qr (qp, np, 2 * qn, dp, qn, dinv);
+      else
+       cy = mpn_dc_bdiv_qr_n (qp, np, dp, qn, dinv, tp);
+
+      if (qn != dn)
+       {
+         if (qn > dn - qn)
+           mpn_mul (tp, qp, qn, dp + qn, dn - qn);
+         else
+           mpn_mul (tp, dp + qn, dn - qn, qp, qn);
+         mpn_incr_u (tp + qn, cy);
+
+         mpn_sub (np + qn, np + qn, nn - qn, tp, dn);
+         cy = 0;
+       }
+
+      np += qn;
+      qp += qn;
+
+      qn = nn - qn;
+      while (qn > dn)
+       {
+         mpn_sub_1 (np + dn, np + dn, qn, cy);
+         cy = mpn_dc_bdiv_qr_n (qp, np, dp, dn, dinv, tp);
+         qp += dn;
+         np += dn;
+         qn -= dn;
+       }
+      mpn_sub_1 (np + dn, np + dn, qn, cy);
+      mpn_dc_bdiv_q_n (qp, np, dp, dn, dinv, tp);
+      TMP_FREE;
+      return;
+    }
+
+  if (BELOW_THRESHOLD (qn, DC_BDIV_Q_THRESHOLD))
+    mpn_sb_bdiv_q (qp, np, 2 * qn, dp, qn, dinv);
+  else
+    mpn_dc_bdiv_q_n (qp, np, dp, qn, dinv, tp);
+
+  TMP_FREE;
+}