* Juan Quintela (quint...@redhat.com) wrote:
> <arei.gong...@huawei.com> wrote:
> > From: ChenLiang <chenlian...@huawei.com>
> >
> > The logic of old code is correct. But Checking byte by byte will
> > consume time after an concurrency scene.
> >
> > Signed-off-by: ChenLiang <chenlian...@huawei.com>
> > Signed-off-by: Gonglei <arei.gong...@huawei.com>
> > ---
> > xbzrle.c | 28 ++++++++++++++++++----------
> > 1 file changed, 18 insertions(+), 10 deletions(-)
> >
> > diff --git a/xbzrle.c b/xbzrle.c
> > index d27a140..0477367 100644
> > --- a/xbzrle.c
> > +++ b/xbzrle.c
> > @@ -50,16 +50,24 @@ int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t
> > *new_buf, int slen,
> >
> > /* word at a time for speed */
> > if (!res) {
> > - while (i < slen &&
> > - (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
> > - i += sizeof(long);
> > - zrun_len += sizeof(long);
> > - }
> > -
> > - /* go over the rest */
> > - while (i < slen && old_buf[i] == new_buf[i]) {
> > - zrun_len++;
> > - i++;
> > + while (i < slen) {
> > + if ((*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
> > + i += sizeof(long);
> > + zrun_len += sizeof(long);
> > + } else {
> > + /* go over the rest */
> > + for (j = 0; j < sizeof(long); j++) {
> > + if (old_buf[i] == new_buf[i]) {
> > + i++;
> > + zrun_len++;
> > + } else {
> > + break;
> > + }
> > + }
> > + if (j != sizeof(long)) {
> > + break;
> > + }
> > + }
> > }
> > }
>
> This still does misaligned reads. If we want to do aligned stuff,
> something like that looks much better, no? Notice that where I put
> "break", I mean we have finished, but you get the idea. Or I am missing
> something?
You're missing the loop just above this code that's changed that
guarantees alginment by the start of this code.
Dave
>
> while(i % sizeof(long) != 0) {
> if (old_buf[i] == new_buf[i]) {
> i++;
> zrun_len++;
> } else {
> break;
> }
> }
>
> while (i < slen) {
> if ((*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
> i += sizeof(long);
> zrun_len += sizeof(long);
> } else {
> break;
> }
> }
>
> for (j = 0; j < sizeof(long); j++) {
> if (old_buf[i] == new_buf[i]) {
> i++;
> zrun_len++;
> } else {
> break;
> }
> }
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
