On Fri, Mar 14, 2014 at 03:38:55PM +0000, Peter Maydell wrote: > On 14 March 2014 15:36, Richard W.M. Jones <rjo...@redhat.com> wrote: > > On Fri, Mar 14, 2014 at 06:50:37AM -0400, Jeff Cody wrote: > >> On 32-bit hosts, some compilers will warn on too large integer constants > >> for constants that are 64-bit in length. Explicitly put a 'ULL' suffix > >> on those defines. > >> -#define VHDX_FILE_SIGNATURE 0x656C696678646876 /* "vhdxfile" in ASCII */ > >> +#define VHDX_FILE_SIGNATURE 0x656C696678646876ULL /* "vhdxfile" in ASCII > >> */ > > > > I think it's better to use this C99-defined feature (from <stdint.h>): > > > > #define VHDX_FILE_SIGNATURE UINT64_C(0x656C696678646876) > > Why? It's longer and we barely use it anywhere else > in the codebase, whereas we use the ULL suffix all > over the place...
It's permitted for unsigned long long to be longer than 64 bits. The UINT64_C() macro will always return a 64 bit int constant. Yup, it's not likely and for this particular macro it wouldn't matter. (And I'm not going to get into language-lawyering ...) Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top
