Detect system architecture (x86/x64) while running

Question

Is it possible to detect the system/processor architecture while the program is running (under windows and under linux) in c++?

Answer 1

On Windows, you may use __cpuid. On Linux, you can open("/proc/cpuinfo") and look through it.

Here is an example on Windows, based on the example in the MSDN page:

#include <intrin.h>

bool cpuSupports64()
{
    int CPUInfo[4];
    __cpuid(CPUInfo, 0);
    return (CPUInfo[3] & 0x20000000) || false;
}

Answer 2

All software approaches will only give you the architecture of the OS you are using. If you are using a 32-bit OS on a 64-bit Hardware, that is what you will get. Among the software approaches are the size of a pointer, the size of a Integer data type or a Float data type. On Linux, you can do a 'uname -a'.

Answer 3

Use GetSystemInfo() or GetNativeSystemInfo() functions under Windows depending on your purpose. I don't know how to do it on Linux though.

Answer 4

Depending on what you intend to do with this information (e.g. select the fastest handcoded assembly code for a specific CPU), under Linux you might want to read /proc/cpuinfo, specifically: the "flags" section, so you can choose between SSE/SSE2 implementation vs. MMX implementation vs. whatever.

Big endian system vs. little endian system is a bit more complicated, refer to: http://en.wikipedia.org/wiki/Endianess

Answer 5

Under Linux, you can use the uname system call. It fills in this user-allocated struct:

  struct utsname {
           char sysname[];    /* Operating system name (e.g., "Linux") */
           char nodename[];   /* Name within "some implementation-defined
                                 network" */
           char release[];    /* OS release (e.g., "2.6.28") */
           char version[];    /* OS version */
           char machine[];    /* Hardware identifier */
       #ifdef _GNU_SOURCE
           char domainname[]; /* NIS or YP domain name */
       #endif
       };

The machine field will identify the architecture.