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https://github.com/vale981/arb
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47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/*=============================================================================
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This file is part of ARB.
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ARB is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ARB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with ARB; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2016 Pascal Molin
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******************************************************************************/
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#include "dlog.h"
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/* assume mod is small so no overflow */
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ulong
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dlog_table_init(dlog_table_t t, ulong a, ulong mod)
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{
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int k;
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ulong ak;
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t->mod = mod;
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t->table = flint_malloc(mod * sizeof(ulong));
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ak = 1; k = 0;
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/* warning: do not check a is invertible modulo mod */
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do
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{
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t->table[ak] = k++;
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ak = (ak * a) % mod;
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}
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while (ak != 1);
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return 1;
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}
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