detect cpu type c++

Allan · 2008-03-24 04:58:08

I have a template class that hold numeric data (for simplicity think of it as a vector). When I do addition, I want to have the type promotion handled automatically.

The only problem is in the case of adding an unsigned int and a long. On 32 bit computer, this should resulting in a unsigned int. On an 64 bit computer it will result in a long.

My question is, how can I tell within my code whether it is being compiled on a 32 or 64 bit cpu?

wuischke · 2008-03-24 07:04:04

limits.h and inttypes.h use

#if __WORDSIZE == 64

to check for 32/64 bit systems on build time. The definition is in bits/wordsize.h where a check for

#if defined __x86_64__

is done.
The first variant is most probably more portable (think e.g. of PPC64), but I believe both are limited to gcc.

Last edited by wuischke (2008-03-24 07:05:04)

Allan · 2008-03-24 08:03:39

Thanks for the ideas. It appears that the "__WORDSIZE" definition is a glibc construct. I see "__x86_64__" is used in libpng and mono so perhaps that is a gcc define. Going to look into this now.

Allan · 2008-03-24 08:30:00

Well, I just found this command to list all gcc internal definitions

echo "" | g++ -E -dM -x c - | sort | less

i386 (and variants __i386 and __i386__) are defined by gcc on linux and in mingw on windows. Now I have to decide what platforms I would like support...

Arch Linux

#1 2008-03-24 04:58:08

detect cpu type c++

#2 2008-03-24 07:04:04

Re: detect cpu type c++

#3 2008-03-24 08:03:39

Re: detect cpu type c++

#4 2008-03-24 08:30:00

Re: detect cpu type c++

Board footer