cpu.cpp

Go to the documentation of this file.

/*
 * 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 <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "stdafx.h"
#include "core/bitmath_func.hpp"
#include "cpu.h"
 
#include "safeguards.h"

using CPUIDArray = std::array<int, 4>;

static CPUIDArray CPUID([[maybe_unused]] int type)
{
  CPUIDArray info{};
#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
  __cpuid(info.data(), type);
#elif defined(__i386) && defined(__PIC__)
  /* The easy variant would be just cpuid, however... ebx is being used by the GOT (Global Offset Table)
   * in case of PIC;
   * clobbering ebx is no alternative: some compiler versions don't like this
   * and will issue an error message like
   *   "can't find a register in class 'BREG' while reloading 'asm'"
   */
  __asm__ __volatile__ (
      "xchgl %%ebx, %1 \n\t"
      "cpuid           \n\t"
      "xchgl %%ebx, %1 \n\t"
      : "=a" (info[0]), "=r" (info[1]), "=c" (info[2]), "=d" (info[3])
      /* It is safe to write "=r" for (info[1]) as in case that PIC is enabled for i386,
       * the compiler will not choose EBX as target register (but something else).
       */
      : "a" (type)
  );
#elif defined(__x86_64__) || defined(__i386)
  __asm__ __volatile__ (
      "cpuid           \n\t"
      : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
      : "a" (type)
  );
#elif defined(__e2k__) /* MCST Elbrus 2000*/
  if (type == 0) {
    info[0] = 1;
  } else if (type == 1) {
# if defined(__SSE4_1__)
    info[2] |= (1<<19); /* HasCPUIDFlag(1, 2, 19) */
# endif
# if defined(__SSSE3__)
    info[2] |= (1<<9); /* HasCPUIDFlag(1, 2, 9) */
# endif
# if defined(__SSE2__)
    info[3] |= (1<<26); /* HasCPUIDFlag(1, 3, 26) */
# endif
  }
#endif
  return info;
}
 
bool HasCPUIDFlag(uint type, uint index, uint bit)
{
  CPUIDArray cpu_info = CPUID(0);
  uint max_info_type = cpu_info[0];
  if (max_info_type < type) return false;
 
  cpu_info = CPUID(type);
  return HasBit(cpu_info[index], bit);
}