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-rw-r--r--Build/source/libs/gmp/gmp-src/mpn/generic/sbpi1_bdiv_q.c78
1 files changed, 37 insertions, 41 deletions
diff --git a/Build/source/libs/gmp/gmp-src/mpn/generic/sbpi1_bdiv_q.c b/Build/source/libs/gmp/gmp-src/mpn/generic/sbpi1_bdiv_q.c
index 645b1d9b6a4..850e593776d 100644
--- a/Build/source/libs/gmp/gmp-src/mpn/generic/sbpi1_bdiv_q.c
+++ b/Build/source/libs/gmp/gmp-src/mpn/generic/sbpi1_bdiv_q.c
@@ -1,13 +1,13 @@
/* mpn_sbpi1_bdiv_q -- schoolbook Hensel division with precomputed inverse,
returning quotient only.
- Contributed to the GNU project by Niels Möller.
+ Contributed to the GNU project by Niels Möller and Torbjörn Granlund.
THE FUNCTIONS IN THIS FILE ARE INTERNAL FUNCTIONS WITH MUTABLE INTERFACES.
IT IS ONLY SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS
ALMOST GUARANTEED THAT THEY'LL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
-Copyright 2005, 2006, 2009, 2011, 2012 Free Software Foundation, Inc.
+Copyright 2005, 2006, 2009, 2011, 2012, 2017 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
@@ -35,66 +35,62 @@ You should have received copies of the GNU General Public License and the
GNU Lesser General Public License along with the GNU MP Library. If not,
see https://www.gnu.org/licenses/. */
-#include "gmp.h"
#include "gmp-impl.h"
-
-/* Computes Q = N / D mod B^nn, destroys N.
+/* Computes Q = - U / D mod B^un, destroys U.
D must be odd. dinv is (-D)^-1 mod B.
-
- The straightforward way to compute Q is to cancel one limb at a time, using
-
- qp[i] = D^{-1} * np[i] (mod B)
- N -= B^i * qp[i] * D
-
- But we prefer addition to subtraction, since mpn_addmul_1 is often faster
- than mpn_submul_1. Q = - N / D can be computed by iterating
-
- qp[i] = (-D)^{-1} * np[i] (mod B)
- N += B^i * qp[i] * D
-
- And then we flip the sign, -Q = (not Q) + 1. */
+*/
void
mpn_sbpi1_bdiv_q (mp_ptr qp,
- mp_ptr np, mp_size_t nn,
+ mp_ptr up, mp_size_t un,
mp_srcptr dp, mp_size_t dn,
mp_limb_t dinv)
{
mp_size_t i;
- mp_limb_t cy, q;
+ mp_limb_t q;
ASSERT (dn > 0);
- ASSERT (nn >= dn);
+ ASSERT (un >= dn);
ASSERT ((dp[0] & 1) != 0);
- /* FIXME: Add ASSERTs for allowable overlapping; i.e., that qp = np is OK,
- but some over N/Q overlaps will not work. */
+ ASSERT (-(dp[0] * dinv) == 1);
+ ASSERT (up == qp || !MPN_OVERLAP_P (up, un, qp, un - dn));
- for (i = nn - dn; i > 0; i--)
+ if (un > dn)
{
- q = dinv * np[0];
- cy = mpn_addmul_1 (np, dp, dn, q);
- mpn_add_1 (np + dn, np + dn, i, cy);
- ASSERT (np[0] == 0);
- qp[0] = ~q;
- qp++;
- np++;
+ mp_limb_t cy, hi;
+ for (i = un - dn - 1, cy = 0; i > 0; i--)
+ {
+ q = dinv * up[0];
+ hi = mpn_addmul_1 (up, dp, dn, q);
+
+ ASSERT (up[0] == 0);
+ *qp++ = q;
+ hi += cy;
+ cy = hi < cy;
+ hi += up[dn];
+ cy += hi < up[dn];
+ up[dn] = hi;
+ up++;
+ }
+ q = dinv * up[0];
+ hi = cy + mpn_addmul_1 (up, dp, dn, q);
+ ASSERT (up[0] == 0);
+ *qp++ = q;
+ up[dn] += hi;
+ up++;
}
-
for (i = dn; i > 1; i--)
{
- q = dinv * np[0];
- mpn_addmul_1 (np, dp, i, q);
- ASSERT (np[0] == 0);
- qp[0] = ~q;
- qp++;
- np++;
+ mp_limb_t q = dinv * up[0];
+ mpn_addmul_1 (up, dp, i, q);
+ ASSERT (up[0] == 0);
+ *qp++ = q;
+ up++;
}
/* Final limb */
- q = dinv * np[0];
- qp[0] = ~q;
- mpn_add_1 (qp - nn + 1, qp - nn + 1, nn, 1);
+ *qp = dinv * up[0];
}