Revision 04d936b111068ed0247613675a3c458b6b5feb5b authored by Alexander Kruppa on 19 February 2014, 14:03:37 UTC, committed by Alexander Kruppa on 19 February 2014, 14:03:37 UTC
1 parent 869d21a
mul6k_a.c
/* This file is part of the gf2x library.
Copyright 2007, 2008, 2009
Richard Brent, Pierrick Gaudry, Emmanuel Thome', Paul Zimmermann
This program 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 2.1 of the License, or (at
your option) any later version.
This program 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 CADO-NFS; see the file COPYING. If not, write to
the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef GF2X_MUL6_H_
#define GF2X_MUL6_H_
#include "gf2x.h"
/* All gf2x source files for lowlevel functions must include gf2x-small.h
* This is mandatory for the tuning mechanism. */
#include "gf2x/gf2x-small.h"
GF2X_STORAGE_CLASS_mul6
void gf2x_mul6 (unsigned long *c, const unsigned long *a, const unsigned long *b)
{
/* This code uses the K3 formula from Weimerskirch and Paar,
http://weimerskirch.org/papers/Weimerskirch_Karatsuba.pdf,
which performs only 6 calls to gf2x_mul2. */
unsigned long d01[4], d1[4], d12[4], aa[2], bb[2];
gf2x_mul2 (c, a, b); /* D0 */
gf2x_mul2 (d1, a + 2, b + 2); /* D1 */
gf2x_mul2 (c + 8, a + 4, b + 4); /* D2 */
aa[0] = a[0] ^ a[2]; aa[1] = a[1] ^ a[3];
bb[0] = b[0] ^ b[2]; bb[1] = b[1] ^ b[3];
gf2x_mul2 (d01, aa, bb); /* D01 */
aa[0] = a[0] ^ a[4]; aa[1] = a[1] ^ a[5];
bb[0] = b[0] ^ b[4]; bb[1] = b[1] ^ b[5];
gf2x_mul2 (c + 4, aa, bb); /* D02 */
aa[0] = a[2] ^ a[4]; aa[1] = a[3] ^ a[5];
bb[0] = b[2] ^ b[4]; bb[1] = b[3] ^ b[5];
gf2x_mul2 (d12, aa, bb); /* D12 */
/* low(D1) + high(D0) is used three times */
c[2] ^= d1[0]; c[3] ^= d1[1]; /* low(D1) + high(D0) */
c[4] ^= c[2]; c[5] ^= c[3]; /* low(D02) + low(D1) + high(D0) */
d12[0] ^= c[2]; d12[1] ^= c[3]; /* low(D12) + low(D1) + high(D0) */
/* low(D2) + high(D1) is used three times */
c[8] ^= d1[2]; c[9] ^= d1[3]; /* low(D2) + high(D1) */
c[6] ^= c[8]; c[7] ^= c[9]; /* high(D02) + low(D2) + high(D1) */
d01[2] ^= c[8]; d01[3] ^= c[9]; /* high(D01) + low(D2) + high(D1) */
c[2] ^= d01[0] ^ c[0]; c[3] ^= d01[1] ^ c[1]; /* l(D1)+h(D0)+l(D01)+l(D0) */
c[4] ^= c[0] ^ d01[2]; c[5] ^= c[1] ^ d01[3];
c[6] ^= d12[0] ^ c[10]; c[7] ^= d12[1] ^ c[11];
c[8] ^= d12[2] ^ c[10]; c[9] ^= d12[3] ^ c[11];
}
#endif /* GF2X_MUL6_H_ */
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