OpenTTD
cpu.cpp
Go to the documentation of this file.
1 /* $Id: cpu.cpp 26482 2014-04-23 20:13:33Z 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 
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 
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 }
Functions related to bit mathematics.
Definition of base types and functions in a cross-platform compatible way.
A number of safeguards to prevent using unsafe methods.
bool HasCPUIDFlag(uint type, uint index, uint bit)
Check whether the current CPU has the given flag.
Definition: cpu.cpp:133
void ottd_cpuid(int info[4], int type)
Definitions for CPU detection:
Definition: cpu.cpp:127
static bool HasBit(const T x, const uint8 y)
Checks if a bit in a value is set.
uint64 ottd_rdtsc()
Get the tick counter from the CPU (high precision timing).
Definition: cpu.cpp:78