On Wed, 27 May 2015 10:41:06 +0530 Nikunj A Dadhania <nik...@linux.vnet.ibm.com> wrote:
> Greg Kurz <gk...@linux.vnet.ibm.com> writes: > > > SLOF currently calls hv-logical-load and hv-logical-store for every pixel > > when enabling or disabling the cursor. This is suboptimal when writing one > > char at a time to the console since terminal-write always toggles the > > cursor. > > And this is precisely what grub is doing when the user wants to edit a menu > > entry... the result is an incredibly slow and barely usable interface. > > > > The inner loop in fb8-toggle-cursor handles a contiguous region: it can be > > converted to hv-logical-memop. The result is 32 times less hcalls per char > > and a serious improvement in grub usability. > > > > Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com> > > --- > > slof/fs/fbuffer.fs | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/slof/fs/fbuffer.fs b/slof/fs/fbuffer.fs > > index 756f05a..46b59bf 100644 > > --- a/slof/fs/fbuffer.fs > > +++ b/slof/fs/fbuffer.fs > > @@ -99,8 +99,8 @@ CREATE bitmap-buffer 400 4 * allot > > : fb8-toggle-cursor ( -- ) > > line# fb8-line2addr column# fb8-columns2bytes + > > char-height 0 ?DO > > - char-width screen-depth * 0 ?DO dup dup rb@ -1 xor swap rb! 1+ > > LOOP > > - screen-width screen-depth * + char-width screen-depth * - > > + dup dup 0 char-width screen-depth * 1 hv-logical-memop drop > > + screen-width screen-depth * + > > Why did you drop "char-width screen-depth * -" in the new code? This is > not me mentioned in the description. > This is because the current inner loop increments the address. When the loop ends, we're pointing at the next char, that is char-width * screen-depth bytes too far. In the new code, the address is duped on the stack before calling hv-logical-memop, so we don't need to fix it when proceeding to next line. In my first attempt, I forgot to drop the subtraction and got an interesting visual result :) > Regards > Nikunj Cheers. -- Greg _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
