While writing new code for Windows, I stumbled upon _cpuinfo()
from the Windows API. As I am mainly dealing with a Linux environment (GCC) I want to have access to the CPUInfo.
I have tried the following:
#include <iostream>
int main()
{
int a, b;
for (a = 0; a < 5; a++)
{
__asm ( "mov %1, %%eax; " // a into eax
"cpuid;"
"mov %%eax, %0;" // eax into b
:"=r"(b) // output
:"r"(a) // input
:"%eax","%ebx","%ecx","%edx" // clobbered register
);
std::cout << "The code " << a << " gives " << b << std::endl;
}
return 0;
}
This use assembly but I don't want to re-invent the wheel. Is there any other way to implement CPUInfo without assembly?
Compiler errors:
lewis@lewis-desktop:~/Desktop/prog$ g++ -Wall CPUInfo.cpp
CPUInfo.cpp: In function ‘int main()’:
CPUInfo.cpp:10:22: error: expected ‘)’ before ‘;’ token
CPUInfo.cpp:10:23: error: expected primary-expression before ‘)’ token
CPUInfo.cpp:10:23: error: expected ‘;’ before ‘)’ token
CPUInfo.cpp:8:8: warning: unused variable ‘b’ [-Wunused-variable]
CPUInfo.cpp:12:8: error: expected ‘}’ at end of input
Since you are compiling with GCC then you can include cpuid.h
which declares these functions:
/* Return highest supported input value for cpuid instruction. ext can
be either 0x0 or 0x8000000 to return highest supported value for
basic or extended cpuid information. Function returns 0 if cpuid
is not supported or whatever cpuid returns in eax register. If sig
pointer is non-null, then first four bytes of the signature
(as found in ebx register) are returned in location pointed by sig. */
unsigned int __get_cpuid_max (unsigned int __ext, unsigned int *__sig)
/* Return cpuid data for requested cpuid level, as found in returned
eax, ebx, ecx and edx registers. The function checks if cpuid is
supported and returns 1 for valid cpuid information or 0 for
unsupported cpuid level. All pointers are required to be non-null. */
int __get_cpuid (unsigned int __level,
unsigned int *__eax, unsigned int *__ebx,
unsigned int *__ecx, unsigned int *__edx)
You don't need to, and should not, re-implement this functionality.