Re: [Qemu-devel] [PATCH v2 3/6] target-ppc: add vrldnmi and vrlwmi instructions

[David Gibson]

On Thu, Oct 27, 2016 at 02:03:01PM +0530, Nikunj A Dadhania wrote:
> David Gibson <address@hidden> writes:
> >> diff --git a/target-ppc/int_helper.c b/target-ppc/int_helper.c
> >> index dca4798..b54cd7c 100644
> >> --- a/target-ppc/int_helper.c
> >> +++ b/target-ppc/int_helper.c
> >> @@ -1717,6 +1717,52 @@ void helper_vrsqrtefp(CPUPPCState *env, ppc_avr_t 
> >> *r, ppc_avr_t *b)
> >>      }
> >>  }
> >>  
> >> +#define MASK(size, max_val)                                     \
> >> +static inline uint##size##_t mask_u##size(uint##size##_t start, \
> >> +                                uint##size##_t end)             \
> >> +{                                                               \
> >> +    uint##size##_t ret, max_bit = size - 1;                     \
> >> +                                                                \
> >> +    if (likely(start == 0)) {                                   \
> >> +        ret = max_val << (max_bit - end);                       \
> >> +    } else if (likely(end == max_bit)) {                        \
> >> +        ret = max_val >> start;                                 \
> >> +    } else {                                                    \
> >> +        ret = (((uint##size##_t)(-1ULL)) >> (start)) ^          \
> >> +            (((uint##size##_t)(-1ULL) >> (end)) >> 1);          \
> >> +        if (unlikely(start > end)) {                            \
> >> +            return ~ret;                                        \
> >> +        }                                                       \
> >> +    }                                                           \
> >> +                                                                \
> >> +    return ret;                                                 \
> >> +}
> >> +
> >> +MASK(32, UINT32_MAX);
> >> +MASK(64, UINT64_MAX);
> >
> > It would be nicer to merge this mask generation with the
> > implementation in target-ppc/translate.c (called MASK()).
> 
> How about something like this in target-ppc/cpu.h
> 
> #define FUNC_MASK(name, ret_type, size, max_val)                  \
> static inline ret_type name (uint##size##_t start,                \
>                              uint##size##_t end)                  \
> {                                                                 \
>     ret_type ret, max_bit = size - 1;                             \
>                                                                   \
>     if (likely(start == 0)) {                                     \
>         ret = max_val << (max_bit - end);                         \
>     } else if (likely(end == max_bit)) {                          \
>         ret = max_val >> start;                                   \
>     } else {                                                      \
>         ret = (((uint##size##_t)(-1ULL)) >> (start)) ^            \
>             (((uint##size##_t)(-1ULL) >> (end)) >> 1);            \
>         if (unlikely(start > end)) {                              \
>             return ~ret;                                          \
>         }                                                         \
>     }                                                             \
>                                                                   \
>     return ret;                                                   \
> }
> 
> #if defined(TARGET_PPC64)
> FUNC_MASK(MASK, target_ulong, 64, UINT64_MAX);
> #else
> FUNC_MASK(MASK, target_ulong, 32, UINT32_MAX);
> #endif
> FUNC_MASK(mask_u32, uint32_t, 32, UINT32_MAX);
> FUNC_MASK(mask_u64, uint64_t, 64, UINT64_MAX);

That seems reasonable.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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