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https://github.com/vale981/arb
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33 lines
781 B
C
33 lines
781 B
C
/*
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Copyright (C) 2016 Pascal Molin
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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 it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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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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