On 12 April 2011 22:32, Aurelien Jarno <aurel...@aurel32.net> wrote:
> On Mon, Apr 11, 2011 at 04:32:08PM +0100, Peter Maydell wrote:
>> @@ -1524,12 +1528,12 @@ uint64_t HELPER(neon_abdl_u16)(uint32_t a, uint32_t
>> b)
>> {
>> uint64_t tmp;
>> uint64_t result;
>> - DO_ABD(result, a, b, uint8_t);
>> - DO_ABD(tmp, a >> 8, b >> 8, uint8_t);
>> + DO_ABD(result, a, b, uint8_t, uint32_t);
>> + DO_ABD(tmp, a >> 8, b >> 8, uint8_t, uint32_t);
>> result |= tmp << 16;
>> - DO_ABD(tmp, a >> 16, b >> 16, uint8_t);
>> + DO_ABD(tmp, a >> 16, b >> 16, uint8_t, uint32_t);
>> result |= tmp << 32;
>> - DO_ABD(tmp, a >> 24, b >> 24, uint8_t);
>> + DO_ABD(tmp, a >> 24, b >> 24, uint8_t, uint32_t);
>> result |= tmp << 48;
>> return result;
>> }
>
> Do we really need a 32-bit type for the computation here?
No, anything wider than 8 will do, but my guess was that in
practice 32 bits would be fractionally more efficient than
unnecessarily forcing 16 bit arithmetic. For that matter I
guess we could just say "int" and "unsigned int" since C
guarantees us at least 16 bits there.
-- PMM
