[FFmpeg-devel] a64 encoder 7th round

[Michael Niedermayer]

On Tue, Feb 03, 2009 at 03:22:21PM +0100, Bitbreaker/METALVOTZE wrote:
> > ldx $de00
> > lda lut+0,x
> > sta dest,y
> > lda lut+1,x
> > sta dest+64,y
> > lda lut+2,x
> > sta dest+128,y
> > lda lut+3,x
> > sta dest+192,y
> > iny
> 
> Just tested something similar to reconstruct the "compressed" colorram. 
> However it spoils of course my option of linear writing and thus things 
> need to happen even faster as i write at the lower and upper end of the 
> colorram area at the same time. It works out tightly however when i 
> start 44 lines before screen ends. Writing endures until i enter the 
> upper area again, but ends luckily fast enough (4 lines) before the last 
> line of the first 0x100 block of colorram is displayed. So i have to 
> take care that i cross no 0x100 border codewise and indexwise, as that 
> would add extra cycles and thus trash display. I could however place the 
> LUT into zeropage where no extar cycles apply on those conditions. Would 
> make things more stable, 

> but wastes 64 nice favourite places to store 
> values when running out of registers ;-)

19 not 64 (see my previous reply for the actual table
you need just 2^n + n - 1 not 2^n * n with overlapping entries

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No snowflake in an avalanche ever feels responsible. -- Voltaire
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