Messages in this thread | | | Date | Wed, 3 Oct 2007 13:12:11 +0100 | From | Ralf Baechle <> | Subject | Re: [COMPAT] Add compat_merge64 helper |
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On Sat, Sep 29, 2007 at 11:48:52AM +0200, Heiko Carstens wrote:
> > +static inline u64 compat_merge64(u32 left, u32 right) > > +{ > > +#if defined(__BIG_ENDIAN) > > + return ((u64)left << 32) | right; > > +#else /* defined (__LITTLE_ENDIAN) */ > > Could you change that to an #elif please and #error out if none is defined? > Should safe us from subtle bugs caused by missing includes.
This funny macro gets away without any extra headers or #ifdef messiness:
#define merge_64(r1,r2) \ ({ \ union { \ int __words[2]; \ long long __dword; \ } __u = { \ .__words = { (r1), (r2) } \ }; \ \ __u.__dword; \ })
Thanks to gcc doing bogus sign and zero extensions it compiles into slightly larger code for MIPS but that may not be an issue on other architectures.
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