src/cpu.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /** @file cpu.cpp OS/CPU/compiler dependent CPU specific calls. */
   9
  10 #include "stdafx.h"
  11 #include "core/bitmath_func.hpp"
  12
  13 #include "safeguards.h"
  14
  15 /**
  16  * Definitions for CPU detection:
  17  *
  18  * MSVC offers cpu information while gcc only implements in gcc 4.8
  19  * __builtin_cpu_supports and friends
  20  * http://msdn.microsoft.com/library/vstudio/hskdteyh%28v=vs.100%29.aspx
  21  * http://gcc.gnu.org/onlinedocs/gcc/X86-Built-in-Functions.html
  22  *
  23  * Other platforms/architectures don't have CPUID, so zero the info and then
  24  * most (if not all) of the features are set as if they do not exist.
  25  */
  26 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
  27 void ottd_cpuid(int info[4], int type)
  28 {
  29         __cpuid(info, type);
  30 }
  31 #elif defined(__x86_64__) || defined(__i386)
  32 void ottd_cpuid(int info[4], int type)
  33 {
  34 #if defined(__i386) && defined(__PIC__)
  35         /* The easy variant would be just cpuid, however... ebx is being used by the GOT (Global Offset Table)
  36          * in case of PIC;
  37          * clobbering ebx is no alternative: some compiler versions don't like this
  38          * and will issue an error message like
  39          *   "can't find a register in class 'BREG' while reloading 'asm'"
  40          */
  41         __asm__ __volatile__ (
  42                         "xchgl %%ebx, %1 \n\t"
  43                         "cpuid           \n\t"
  44                         "xchgl %%ebx, %1 \n\t"
  45                         : "=a" (info[0]), "=r" (info[1]), "=c" (info[2]), "=d" (info[3])
  46                         /* It is safe to write "=r" for (info[1]) as in case that PIC is enabled for i386,
  47                          * the compiler will not choose EBX as target register (but something else).
  48                          */
  49                         : "a" (type)
  50         );
  51 #else
  52         __asm__ __volatile__ (
  53                         "cpuid           \n\t"
  54                         : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
  55                         : "a" (type)
  56         );
  57 #endif /* i386 PIC */
  58 }
  59 #elif defined(__e2k__) /* MCST Elbrus 2000*/
  60 void ottd_cpuid(int info[4], int type)
  61 {
  62         info[0] = info[1] = info[2] = info[3] = 0;
  63         if (type == 0) {
  64                 info[0] = 1;
  65         } else if (type == 1) {
  66 #if defined(__SSE4_1__)
  67                 info[2] |= (1<<19); /* HasCPUIDFlag(1, 2, 19) */
  68 #endif
  69 #if defined(__SSSE3__)
  70                 info[2] |= (1<<9); /* HasCPUIDFlag(1, 2, 9) */
  71 #endif
  72 #if defined(__SSE2__)
  73                 info[3] |= (1<<26); /* HasCPUIDFlag(1, 3, 26) */
  74 #endif
  75         }
  76 }
  77 #else
  78 void ottd_cpuid(int info[4], int)
  79 {
  80         info[0] = info[1] = info[2] = info[3] = 0;
  81 }
  82 #endif
  83
  84 bool HasCPUIDFlag(uint type, uint index, uint bit)
  85 {
  86         int cpu_info[4] = {-1};
  87         ottd_cpuid(cpu_info, 0);
  88         uint max_info_type = cpu_info[0];
  89         if (max_info_type < type) return false;
  90
  91         ottd_cpuid(cpu_info, type);
  92         return HasBit(cpu_info[index], bit);
  93 }