arb/dlog/modpe.c

56 lines
1.7 KiB
C

/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2016 Pascal Molin
******************************************************************************/
#include "dlog.h"
#include "padic.h"
ulong
dlog_modpe_init(dlog_modpe_t t, ulong a, ulong p, ulong e, ulong pe, ulong num)
{
t->p = p;
t->e = e;
t->pe = pe;
dlog_precomp_n_init(t->modp, a, p, p-1, num);
dlog_1modpe_init(t->modpe, n_powmod(a, p - 1, pe), p, e);
return t->modp->cost + e;
}
void
dlog_modpe_clear(dlog_modpe_t t)
{
dlog_precomp_clear(t->modp);
dlog_1modpe_clear(t->modpe);
}
ulong
dlog_modpe(const dlog_modpe_t t, ulong b)
{
ulong x;
x = dlog_precomp(t->modp, b % t->p);
/*b = b * n_powmod(t->a, -x, t->pe);*/
b = n_powmod(b, t->p - 1, t->pe);
x = x + (t->p-1) * dlog_1modpe(t->modpe, b);
return x;
}