arb/dlog/crt_init.c

83 lines
2.4 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"
ulong
dlog_crt_init(dlog_crt_t t, ulong a, ulong mod, ulong n, ulong num)
{
int k;
n_factor_t fac;
ulong * M, * u;
ulong cost = 0;
n_factor_init(&fac);
n_factor(&fac, n, 1);
t->num = fac.num;
nmod_init(&t->mod,mod);
nmod_init(&t->n, n);
M = t->expo = flint_malloc(t->num * sizeof(ulong));
u = t->crt_coeffs = flint_malloc(t->num * sizeof(ulong));
t->pre = flint_malloc(t->num * sizeof(dlog_precomp_t));
for (k = 0; k < t->num; k++)
t->pre[k] = flint_malloc(sizeof(dlog_precomp_struct));
for (k = 0; k < t->num; k++)
{
ulong p, e, mk;
p = fac.p[k];
e = fac.exp[k];
mk = n_pow(p, e);
M[k] = n / mk;
u[k] = nmod_mul(M[k], n_invmod(M[k] % mk, mk), t->n);
/* depends on the power */
#if 0
flint_printf("[sub-crt -- init for size %wu mod %wu]\n", mk, mod);
#endif
dlog_precomp_pe_init(t->pre[k], nmod_pow_ui(a, M[k], t->mod), mod, p, e, mk, num);
cost += t->pre[k]->cost;
}
#if 0
if (cost > 500)
flint_printf("[crt init for size %wu mod %wu -> cost %wu]\n", n,mod,cost);
#endif
return cost;
}
void
dlog_crt_clear(dlog_crt_t t)
{
int k;
flint_free(t->expo);
flint_free(t->crt_coeffs);
for (k = 0; k < t->num; k++)
{
dlog_precomp_clear(t->pre[k]);
flint_free(t->pre[k]);
}
flint_free(t->pre);
}