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/*
Copyright (C) 2016 Pascal Molin
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "nmod.h"
#include "dlog.h"
/* for odd prime p, assume b1 = 1 mod p */
ulong
dlog_1modpe_1modp(ulong b1, ulong p, ulong e, ulong inv1p, nmod_t pe)
{
int f;
ulong x, xf, pf, pf1;
pf1 = 1;
pf = p;
x = 0;
for (f = 1; f < e; f++)
{
if (b1 % pf != 1)
{
flint_throw(FLINT_ERROR, "ERROR dlog_1modpe_1modp: %wu %% %wu != 1 mod %wu\n\n", b1, pf, pe.n);
}
xf = (b1 - 1) / pf;
xf = (xf % p) * pf1;
x += xf;
b1 = nmod_mul(b1, nmod_pow_ui(inv1p, xf, pe), pe);
pf1 = pf;
pf *= p;
}
return x;
}