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