Re: [Qemu-devel] [RFC PATCH v2 10/15] cpu-model/s390: Add cpu class initialization routines

[Michael Mueller]

On Fri, 20 Feb 2015 10:11:55 -0800
Richard Henderson <address@hidden> wrote:

> > +static inline uint64_t big_endian_bit(unsigned long nr)
> > +{
> > +    return 1ul << (BITS_PER_LONG - (nr % BITS_PER_LONG));
> > +};  
> 
> This is buggy.  NR=0 should map to 63, not 64.

I'm sure I was asked to replace my constant 64 and 63 with that defines and at 
the end I messed
it up... :-(

> 
> > +    return !!(*ptr & big_endian_bit(nr));  
> 
> Personally I dislike !! as an idiom.  Given that big_endian_bit isn't used
> anywhere else, can we integrate it and change this to
> 
> static inline int test_facility(unsigned long nr, uint64_t *fac_list)
> {
>   unsigned long word = nr / BITS_PER_LONG;
>   unsigned long be_bit = 63 - (nr % BITS_PER_LONG);
>   return (fac_list[word] >> be_bit) & 1;
> }

Yes, I just use it in this context. I will integrate your version.

BTW I changed the whole facility defining code to be generated by an external 
helper at compile
time. That is more simple and safe to change. I will send it with v3. See 
attachment for an
example of the generated header file.

Thanks,
Michael

gen-facilities.h
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