history.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "../stdafx.h"
 
#include "../core/bitmath_func.hpp"
#include "history_type.hpp"
#include "history_func.hpp"
 
#include "../safeguards.h"
 
void UpdateValidHistory(ValidHistoryMask &valid_history, const HistoryRange &hr, uint cur_month)
{
  /* Update for subdivisions first. */
  if (hr.hr != nullptr) UpdateValidHistory(valid_history, *hr.hr, cur_month);
 
  /* No need to update if our last entry is marked valid. */
  if (HasBit(valid_history, hr.last - 1)) return;
  /* Is it the right time for this history range? */
  if (cur_month % hr.total_division != 0) return;
  /* Is the previous history range valid yet? */
  if (hr.division != 1 && !HasBit(valid_history, hr.first - hr.division)) return;
 
  SB(valid_history, hr.first, hr.records, GB(valid_history, hr.first, hr.records) << 1ULL | 1ULL);
}
 
bool IsValidHistory(ValidHistoryMask valid_history, const HistoryRange &hr, uint age)
{
  if (hr.hr == nullptr) {
    if (age < hr.periods) {
      uint slot = hr.first + age;
      return HasBit(valid_history, slot);
    }
  } else {
    if (age * hr.division < static_cast<uint>(hr.hr->periods - hr.division)) {
      uint start = age * hr.division + ((TimerGameEconomy::month / hr.hr->division) % hr.division);
      return IsValidHistory(valid_history, *hr.hr, start);
    }
    if (age < hr.periods) {
      uint slot = hr.first + age - ((hr.hr->periods / hr.division) - 1);
      return HasBit(valid_history, slot);
    }
  }
  return false;
}