57 lines
1.7 KiB
C
57 lines
1.7 KiB
C
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/**
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* @file tmtab.h
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* @brief Implements a table of time out values.
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* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
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*
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* This program 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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*
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* This program 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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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_TMTAB_H
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#define HAVE_TMTAB_H
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#include <time.h>
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/*
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* Let 'D' be the logMinDelayReqInterval
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* and 'S' be the logSyncInterval.
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*
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* The delay request interval ranges from zero to 2^{D+1} seconds.
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* The standard requires that
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*
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* S <= D <= S+5
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*
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* and the timeout granularity not more than 2^{S-4} seconds.
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* Thus, the minimum required number of grains is given by
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*
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* 2^{D+1} / 2^{S-4} = 2^{D-S+5}
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*
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* and finds a minimum of 2^5 and a maximum of 2^10.
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*
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* The timeout table allows for the maximum number of grains required.
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*
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* Note that the table is made to be biased so that when sampling the
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* table randomly, the average delay value will be slightly larger
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* than logMinDelayReqInterval, in order to satisfy the wording of the
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* standard.
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*/
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#define TMTAB_MAX 1024
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struct tmtab {
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struct timespec ts[TMTAB_MAX];
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};
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void tmtab_init(struct tmtab *tt, int log_seconds);
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#endif
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