src/cpu.cpp

   1 /* $Id: cpu.cpp 26225 2014-01-04 19:46:24Z rubidium $ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file cpu.cpp OS/CPU/compiler dependent CPU specific calls. */
  11
  12 #include "stdafx.h"
  13 #include "core/bitmath_func.hpp"
  14
  15 #include "safeguards.h"
  16
  17 #undef RDTSC_AVAILABLE
  18
  19 /* rdtsc for MSC_VER, uses simple inline assembly, or _rdtsc
  20  * from external win64.asm because VS2005 does not support inline assembly */
  21 #if defined(_MSC_VER) && !defined(RDTSC_AVAILABLE) && !defined(WINCE)
  22 #include <intrin.h>
  23 uint64 ottd_rdtsc()
  24 {
  25         return __rdtsc();
  26 }
  27 #define RDTSC_AVAILABLE
  28 #endif
  29
  30 /* rdtsc for OS/2. Hopefully this works, who knows */
  31 #if defined (__WATCOMC__) && !defined(RDTSC_AVAILABLE)
  32 unsigned __int64 ottd_rdtsc();
  33 # pragma aux ottd_rdtsc = 0x0F 0x31 value [edx eax] parm nomemory modify exact [edx eax] nomemory;
  34 # define RDTSC_AVAILABLE
  35 #endif
  36
  37 /* rdtsc for all other *nix-en (hopefully). Use GCC syntax */
  38 #if (defined(__i386__) || defined(__x86_64__)) && !defined(__DJGPP__) && !defined(RDTSC_AVAILABLE)
  39 uint64 ottd_rdtsc()
  40 {
  41         uint32 high, low;
  42         __asm__ __volatile__ ("rdtsc" : "=a" (low), "=d" (high));
  43         return ((uint64)high << 32) | low;
  44 }
  45 # define RDTSC_AVAILABLE
  46 #endif
  47
  48 /* rdtsc for PPC which has this not */
  49 #if (defined(__POWERPC__) || defined(__powerpc__)) && !defined(RDTSC_AVAILABLE)
  50 uint64 ottd_rdtsc()
  51 {
  52         uint32 high = 0, high2 = 0, low;
  53         /* PPC does not have rdtsc, so we cheat by reading the two 32-bit time-counters
  54          * it has, 'Move From Time Base (Upper)'. Since these are two reads, in the
  55          * very unlikely event that the lower part overflows to the upper part while we
  56          * read it; we double-check and reread the registers */
  57         asm volatile (
  58                                   "mftbu %0\n"
  59                                   "mftb %1\n"
  60                                   "mftbu %2\n"
  61                                   "cmpw %3,%4\n"
  62                                   "bne- $-16\n"
  63                                   : "=r" (high), "=r" (low), "=r" (high2)
  64                                   : "0" (high), "2" (high2)
  65                                   );
  66         return ((uint64)high << 32) | low;
  67 }
  68 # define RDTSC_AVAILABLE
  69 #endif
  70
  71 /* In all other cases we have no support for rdtsc. No major issue,
  72  * you just won't be able to profile your code with TIC()/TOC() */
  73 #if !defined(RDTSC_AVAILABLE)
  74 /* MSVC (in case of WinCE) can't handle #warning */
  75 # if !defined(_MSC_VER)
  76 #warning "(non-fatal) No support for rdtsc(), you won't be able to profile with TIC/TOC"
  77 # endif
  78 uint64 ottd_rdtsc() {return 0;}
  79 #endif
  80
  81
  82 /**
  83  * Definitions for CPU detection:
  84  *
  85  * MSVC offers cpu information while gcc only implements in gcc 4.8
  86  * __builtin_cpu_supports and friends
  87  * http://msdn.microsoft.com/library/vstudio/hskdteyh%28v=vs.100%29.aspx
  88  * http://gcc.gnu.org/onlinedocs/gcc/X86-Built-in-Functions.html
  89  *
  90  * Other platforms/architectures don't have CPUID, so zero the info and then
  91  * most (if not all) of the features are set as if they do not exist.
  92  */
  93 #if defined(_MSC_VER)
  94 void ottd_cpuid(int info[4], int type)
  95 {
  96         __cpuid(info, type);
  97 }
  98 #elif defined(__x86_64__) || defined(__i386)
  99 void ottd_cpuid(int info[4], int type)
 100 {
 101 #if defined(__i386) && defined(__PIC__)
 102         /* The easy variant would be just cpuid, however... ebx is being used by the GOT (Global Offset Table)
 103          * in case of PIC;
 104          * clobbering ebx is no alternative: some compiler versions don't like this
 105          * and will issue an error message like
 106          *   "can't find a register in class 'BREG' while reloading 'asm'"
 107          */
 108         __asm__ __volatile__ (
 109                         "xchgl %%ebx, %1 \n\t"
 110                         "cpuid           \n\t"
 111                         "xchgl %%ebx, %1 \n\t"
 112                         : "=a" (info[0]), "=r" (info[1]), "=c" (info[2]), "=d" (info[3])
 113                         /* It is safe to write "=r" for (info[1]) as in case that PIC is enabled for i386,
 114                          * the compiler will not choose EBX as target register (but something else).
 115                          */
 116                         : "a" (type)
 117         );
 118 #else
 119         __asm__ __volatile__ (
 120                         "cpuid           \n\t"
 121                         : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
 122                         : "a" (type)
 123         );
 124 #endif /* i386 PIC */
 125 }
 126 #else
 127 void ottd_cpuid(int info[4], int type)
 128 {
 129         info[0] = info[1] = info[2] = info[3] = 0;
 130 }
 131 #endif
 132
 133 bool HasCPUIDFlag(uint type, uint index, uint bit)
 134 {
 135         int cpu_info[4] = {-1};
 136         ottd_cpuid(cpu_info, 0);
 137         uint max_info_type = cpu_info[0];
 138         if (max_info_type < type) return false;
 139
 140         ottd_cpuid(cpu_info, type);
 141         return HasBit(cpu_info[index], bit);
 142 }