CRAY bitfield support in protocol headers: does anyone care?

Ian Romanick idr at us.ibm.com
Wed Feb 28 15:01:07 PST 2007


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Juliusz Chroboczek wrote:
>> It's not likely that people here don't complain about this here if
>> noone here has access to such an architecture.
> 
> Methinks it's a complier issue, not an architecture issue.  You'd hope
> that C compilers would have learnt to synthesise masks out of sub-word
> struct fields by now.

The CRAY compilers were perfectly within the C spec.  The C spec says,
for example, that "short" must be *at least* 16-bits.  Last time I
checked, 64-bits was at least 16-bits.  It just happens that there's no
way, and there doesn't have to be in C89, to specify exactly 16-bits or
exactly 32-bits.  So, you have to resort to bit-field nonsense.
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