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Michael Lutz

Codechange: Don't use cpp_offsetof in the save/load code.

Many of the member variables that are used in save/load are inside types
that are not standard layout types. Using pointer arithmetics to determine
addresses of members inside types that are not standard layout is generally
undefined behaviour. If we'd use C++17, it is conditionally supported, which means
each compiler may or may not support it. And even then using it for individual
array elements is syntactically not supported the the standard offsetof function.

Unfortunately, the trickery employed for saving linkgraph settings causes quite some
clutter in the settings ini files.

/*
 * 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/>.
 */

/** @file cpu.h Functions related to CPU specific instructions. */

#ifndef CPU_H
#define CPU_H

/**
 * Get the tick counter from the CPU (high precision timing).
 * @return The count.
 */
uint64 ottd_rdtsc();

/**
 * Get the CPUID information from the CPU.
 * @param info The retrieved info. All zeros on architectures without CPUID.
 * @param type The information this instruction should retrieve.
 */
void ottd_cpuid(int info[4], int type);

/**
 * Check whether the current CPU has the given flag.
 * @param type  The type to be passing to cpuid (usually 1).
 * @param index The index in the returned info array.
 * @param bit   The bit index that needs to be set.
 * @return The value of the bit, or false when there is no CPUID or the type is not available.
 */
bool HasCPUIDFlag(uint type, uint index, uint bit);

#endif /* CPU_H */