Il 02/06/2013 16:18, Peter Maydell ha scritto:
> On 31 May 2013 23:18, Richard Henderson <r...@twiddle.net> wrote:
>> On 05/30/2013 02:16 PM, Paolo Bonzini wrote:
>>> +static inline Int128 int128_rshift(Int128 a, int n)
>>> +{
>>> + return (Int128) { (a.lo >> n) | (a.hi << (64 - n)), (a.hi >> n) };
>>> +}
>>
>> Produces wrong results for n == 0, since (a.hi << 64) is undefined.
>
> It produces wrong results for shifts by more than 64,
> for that matter.
This should work:
int64_t h;
if (!n) {
return a;
}
h = a.hi >> n;
if (n >= 64) {
return (Int128) { h, h >> 63 };
} else {
return (Int128) { (a.lo >> n) | (a.hi << (64 - n)), h };
}
Paolo
