On 6/2/15 00:02, Richard Henderson wrote:
> On 05/30/2015 02:17 PM, Chen Gang wrote:
>> + for (count = 0; count < 8; count++) {
>> + sel = (rsrcb >> (count * 8)) & 0xf;
>> + if (sel < 8) {
>> + vdst |= ((rdst >> (8 * sel)) & 0xff) << (count * 8);
>> + } else {
>> + vdst |= ((rsrc >> (8 * (8 - sel))) & 0xff) << (count * 8);
>
> 8 - sel is wrong; you wanted sel - 8.
>
OK, thank you very much.
> That said, you can do better with masking operations. And for brevity, let
> count increment by 8. E.g.
>
> uint64_t vdst = 0;
> int count;
>
> for (count = 0; count < 64; count += 8) {
> uint64_t sel = rsrcb >> count;
> uint64_t src = (sel & 8 ? rsrc : rdst);
> vdst |= ((src >> ((sel & 7) * 8)) & 0xff) << count;
> }
>
OK, thank.
--
Chen Gang
Open, share, and attitude like air, water, and life which God blessed
