--- /dev/null
+/* mpn_dc_bdiv_qr -- divide-and-conquer Hensel division with precomputed
+ inverse, returning quotient and remainder.
+
+ 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 Hensel binary division of {np, 2*n} by {dp, n}.
+
+ Output:
+
+ q = n * d^{-1} mod 2^{qn * GMP_NUMB_BITS},
+
+ r = (n - q * d) * 2^{-qn * GMP_NUMB_BITS}
+
+ Stores q at qp. Stores the n least significant limbs of r at the high half
+ of np, and returns the borrow from the subtraction n - q*d.
+
+ d must be odd. dinv is (-d)^-1 mod 2^GMP_NUMB_BITS. */
+
+mp_size_t
+mpn_dc_bdiv_qr_n_itch (mp_size_t n)
+{
+ return n;
+}
+
+mp_limb_t
+mpn_dc_bdiv_qr_n (mp_ptr qp, mp_ptr np, mp_srcptr dp, mp_size_t n,
+ mp_limb_t dinv, mp_ptr tp)
+{
+ mp_size_t lo, hi;
+ mp_limb_t cy;
+ mp_limb_t rh;
+
+ lo = n >> 1; /* floor(n/2) */
+ hi = n - lo; /* ceil(n/2) */
+
+ if (BELOW_THRESHOLD (lo, DC_BDIV_QR_THRESHOLD))
+ cy = mpn_sb_bdiv_qr (qp, np, 2 * lo, dp, lo, dinv);
+ else
+ cy = mpn_dc_bdiv_qr_n (qp, np, dp, lo, dinv, tp);
+
+ mpn_mul (tp, dp + lo, hi, qp, lo);
+
+ mpn_incr_u (tp + lo, cy);
+ rh = mpn_sub (np + lo, np + lo, n + hi, tp, n);
+
+ if (BELOW_THRESHOLD (hi, DC_BDIV_QR_THRESHOLD))
+ cy = mpn_sb_bdiv_qr (qp + lo, np + lo, 2 * hi, dp, hi, dinv);
+ else
+ cy = mpn_dc_bdiv_qr_n (qp + lo, np + lo, dp, hi, dinv, tp);
+
+ mpn_mul (tp, qp + lo, hi, dp + hi, lo);
+
+ mpn_incr_u (tp + hi, cy);
+ rh += mpn_sub_n (np + n, np + n, tp, n);
+
+ return rh;
+}
+
+mp_limb_t
+mpn_dc_bdiv_qr (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 rr, cy;
+ mp_ptr tp;
+ TMP_DECL;
+
+ TMP_MARK;
+
+ tp = TMP_SALLOC_LIMBS (dn);
+
+ qn = nn - dn;
+
+ if (qn > dn)
+ {
+ /* Reduce qn mod dn without division, optimizing small operations. */
+ 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);
+
+ rr = 0;
+ 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);
+
+ rr = mpn_sub (np + qn, np + qn, nn - qn, tp, dn);
+ cy = 0;
+ }
+
+ np += qn;
+ qp += qn;
+
+ qn = nn - dn - qn;
+ do
+ {
+ rr += 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;
+ }
+ while (qn > 0);
+ TMP_FREE;
+ return rr + cy;
+ }
+
+ 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);
+
+ rr = 0;
+ 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);
+
+ rr = mpn_sub (np + qn, np + qn, nn - qn, tp, dn);
+ cy = 0;
+ }
+
+ TMP_FREE;
+ return rr + cy;
+}
projects / msp430-gcc.git / blobdiff