On 15. Jun, 2009, at 0:15, Hendrik Sattler wrote:
Am Sonntag 14 Juni 2009 22:05:14 schrieb Michael Wild:
On Mac OS X one shouldn't do this kind of detection during configure
step, because as has been mentioned a single file can be compiled
multiple times for different architectures during one single compiler
invocation. The size of void* and even endianness can change. It is
preferable to have a central config.h.in (or similar) containing
something like this:
#if defined(__APPLE__)
# if defined(__i386__)
# undef HAVE_64_BIT
# undef HAVE_BIG_ENDIAN
# elif defined(__ppc__)
# undef HAVE_64_BIT
# define HAVE_BIG_ENDIAN
# elif defined(__x86_64__)
# define HAVE_64_BIT
# undef HAVE_BIG_ENDIAN
# elif defined(__ppc64__)
# define HAVE_64_BIT
# define HAVE_BIG_ENDIAN
# else
// oops
# error "Unknown architecture!"
# endif
#else
# cmakedefine HAVE_64_BIT
# cmakedefine HAVE_BIG_ENDIAN
#endif
Where do you need to know that you have 32bit vs. 64bit?
When including inttypes.h, you can use e.g. uint64_t portably (you
can find
inttypes.h for MSVC on googlecode), else use you can even use:
if (sizeof(void*) == 8) {
...
} else {
...
}
and let the compiler optimize one of them away. Or do something
else with C
preprocessor.
Not _everything_ has to be done with CMake.
HS
True, I can only think of some very low-level stuff where one might
need this kind of knowledge. In all other cases it probably indicates
bad code or design. But then, sometimes one has to deal with a code
somebody else has written...
Michael
_______________________________________________
Powered by www.kitware.com
Visit other Kitware open-source projects at
http://www.kitware.com/opensource/opensource.html
Please keep messages on-topic and check the CMake FAQ at:
http://www.cmake.org/Wiki/CMake_FAQ
Follow this link to subscribe/unsubscribe:
http://www.cmake.org/mailman/listinfo/cmake
