mirror of
https://github.com/vale981/arb
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45 lines
1.1 KiB
C
45 lines
1.1 KiB
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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ulong
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dlog_once(ulong b, ulong a, const nmod_t mod, ulong n)
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{
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if (b == 1)
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return 0;
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if (n < 50)
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{
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slong k;
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ulong ak = 1;
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for (k = 0; k < n; k++)
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{
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if (ak == b)
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return k;
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ak = nmod_mul(ak, a, mod);
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}
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flint_printf("FAIL[dlog once]: log(%wu,%wu) mod %wu not found (size %wu)\n",
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b, a, mod.n, n);
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flint_abort();
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return 0; /* dummy return because flint_abort() is not declared noreturn */
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}
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else
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{
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ulong l;
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dlog_precomp_t pre;
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dlog_precomp_n_init(pre, a, mod.n, n, 1);
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l = dlog_precomp(pre, b);
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dlog_precomp_clear(pre);
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return l;
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}
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}
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