Search found 26 matches

by uko
Wed Mar 04, 2020 10:57 pm
Forum: Professionals
Topic: Wanted: Colours per line routine/prg
Replies: 18
Views: 1255

Re: Wanted: Colours per line routine/prg

mrbombermillzy wrote:@uko: Thankyou. Thats very kind. I would like to take a look at what you have. It sounds very useful. :)

Ok, here it is !
ReduceColors.zip
by uko
Wed Mar 04, 2020 10:44 pm
Forum: Professionals
Topic: Wanted: Colours per line routine/prg
Replies: 18
Views: 1255

Re: Wanted: Colours per line routine/prg

If it may help, I have made a Python script that allows to load an image, to display it, to display number of colours (global or per line), to reduce the number of colors (global or per line) or to split each line and to allow to reimport them. It also can generate the picture (binary format) and pa...
by uko
Sun Feb 16, 2020 7:27 pm
Forum: Coding
Topic: Decreasing colours (algorithm)
Replies: 17
Views: 1542

Re: Decreasing colours (algorithm)

But finally the method I have used is to split the picture in multiple one line image files, then use XnView to convert each line file to x colors (using the batch converter and selecting one dithering method), then reassembling the converted files. So this weekend I wrote a little Delphi tool to s...
by uko
Wed Feb 12, 2020 5:47 pm
Forum: Coding
Topic: Decreasing colours (algorithm)
Replies: 17
Views: 1542

Re: Decreasing colours (algorithm)

Playing a 9600Hz digi-sound means the replay routine should be executed 192 times per VBL. Changing the palette every line means changing it 200 times per VBL. If you use interrupts for both the replay routine (Timer-A) and the color changes (HBL), it will be difficult to avoid interrupts jitter (l...
by uko
Wed Feb 12, 2020 1:03 pm
Forum: Coding
Topic: Decreasing colours (algorithm)
Replies: 17
Views: 1542

Re: Decreasing colours (algorithm)

Hi, I have never tried the tool mentionned by joska, but it seems interesting ! On my side I have used home-made converters to achieve this. I have tried the method you have in mind, Arne, but it provided worse results than simply reducing the bitdepth for each color until you have a maximum of 16 c...
by uko
Sat Jan 18, 2020 7:12 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

fenarinarsa wrote:Don't forget that on Mega STE the blitter takes 4 extra cycles to start ;)

I think Leonard had to take this into account for "We Were@" to work correctly on Mega STE.

Thanks for the info, I'll have to think about that !
by uko
Thu Jan 09, 2020 11:11 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

npomarede wrote:Hopefully, I will be able to fix this in a near future :)

Hopefully I'm a slow coder and it will take me a long time to finish my screen ! :lol:
Thanks.
by uko
Thu Jan 09, 2020 8:16 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

I will have a look at this case ; I have some work in progress to fix some wrong cases where xcount=1 (as Ijor described them to me) and not many time at the moment. I will see if this can be fixed on current code base or if this needs to be part of the rewrite I'm planning to do. Hi ! Thanks for y...
by uko
Thu Jan 09, 2020 6:57 am
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

Everybody is wrong in this case. If XCOUNT is set to one, Blitter doesn't fully honor the NFSR bit and performs a final source read regardless. It might be considered a Blitter buglet, but you shouldn't need to use NFSR if XCOUNT is one. In the post describing the tests I have performed, when I tal...
by uko
Wed Jan 08, 2020 10:10 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

Hi could you provide the executable in your zip archive ? My STE is currently not available (still packed after recently moving home), but maybe some other people here could run your tests on their STE. Nicolas No problem. The source needs to be recompiled to change the test parameters, but I have ...
by uko
Wed Jan 08, 2020 9:45 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

Hi! In order to make things clearer (at least for me !), I have written a little test program to perform some tests and count the number of memory accesses performed by the blitter. The source code is included in the zip file attached to this post. This program blits a one bitplane rectangle onto th...
by uko
Tue Jan 07, 2020 10:36 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

How it would be useful to enable NFSR without a mask ??? In very limited cases... But imagine you have a background using only 3 bitplanes, and a one bitplane sprite of size 16x200 to move over (and of course accurate palette settings). In this case, when you set both SKEW and NFSR, you don't mind ...
by uko
Tue Jan 07, 2020 9:07 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

It is true that there is no much point in using NFSR without a mask. But (if for some reason) NFSR is set and the active mask is $FFFF and the OP mode doesn't require the original dest data, then Blitter doesn't perform a destination read. It may be useful if you use bitplanes as layers, with 16 pi...
by uko
Mon Jan 06, 2020 10:04 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Re: Blitter Execution Times

Nicolas, Thanks for pointing the Hatari source code, I'll have a look to it. I am quite surprised that masking does not add additional cycles, and it seems that in my attempts (but I must check again of course), Hatari uses more cycles when mask is not $FFFF. But I am in the case where XCount = 1 (i...
by uko
Mon Jan 06, 2020 9:06 pm
Forum: Coding
Topic: Blitter Execution Times
Replies: 25
Views: 2779

Blitter Execution Times

Hi ! Up to now I have mainly used the following table to estimate the blitter execution times for sizing my code (and also the Blitter FAQ from The Paranoid of Paradox): http://retrospec.sgn.net/users/tomcat/miodrag/Atari_ST/Atari%20ST%20Internals.htm#BLITTER These timings seem OK as loong as SKEW, ...
by uko
Sun Dec 29, 2019 10:53 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

It had never seen this code before. Thanks for the link. Overscan with some variability of code per line (not interrupt driven) It resynchronises every line at the pixel 292 (byte 146 for first line, and then add 230 bytes for each new line (or other values for hardscroll lines)) using the "cla...
by uko
Sat Dec 28, 2019 1:36 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

Hi Gunstick, nice to see that you have joined the challenge ! In my fist attempt too, interrupts were also consecutive without really any CPU time left in between... But I managed to optimize it (see figures some posts above), especially the synchro before the right border. Anyway it remains a proof...
by uko
Tue Dec 17, 2019 8:40 pm
Forum: 680x0
Topic: Understanding the Union Demo's Opening of left and right borders
Replies: 37
Views: 5404

Re: Understanding the Union Demo's Opening of left and right borders

Thanks ijor for this very clear explanation !
by uko
Wed Dec 11, 2019 9:16 pm
Forum: 680x0
Topic: STE MOD Play code for fullscreen demos
Replies: 4
Views: 1584

STE MOD Play code for fullscreen demos

Hi! There are already a lot of routines to play the Amiga MOD Music files on Atari STE, and when it comes to fast specific STE routines for demomaking, of course the Lance one (and especially the Hacking Lance by Paulo Simoes) is certainly one of the best. But these routines have not fixed CPU time,...
by uko
Mon Dec 09, 2019 10:45 pm
Forum: Demos - General
Topic: Veeeery nice productions of 2019
Replies: 18
Views: 2298

Re: Veeeery nice productions of 2019

It's good to see those very nice prods ! Thanks for the links !
by uko
Mon Oct 21, 2019 8:57 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

Do you know if some emulators are more accurate than others in this way (i.e. the code that works on emulator has more chance to work on real hardware) ? Steem and Hatari are actively developed and have high level of accuracy: https://sourceforge.net/projects/steemsse/files/ https://hatari.tuxfamil...
by uko
Mon Oct 21, 2019 8:54 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

My recommendation, as someone also doing this stuff at the moment, is not to worry so much about the emulator but instead make sure you use a tried and tested shell for your fullscreen code. This might mean you lose some cycles here and there, but better to play it safe in my opinion. (one caveat -...
by uko
Thu Oct 17, 2019 9:47 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

@uko Nice. What kind of effect are you planning to use this for? I am starting an oldskool 50Hz demo. I don't think I'll use this unsynchronous routine for my codings. There is not enough CPU time left, and since I won't do some kind of 3D demo with variable frame rate, it might be simpler to "...
by uko
Thu Oct 17, 2019 9:38 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

Programming fullscreens on hatari usually ends with not working on real hardware. You get flicker issues, plane shifting, and if you use keyboard and dma, you get delays. So expect a little fixing-phase on the real hardware. Thanks for the advice ! Do you know if some emulators are more accurate th...
by uko
Sun Oct 13, 2019 8:28 pm
Forum: 680x0
Topic: unsynchronous fullscreen-routine
Replies: 29
Views: 8397

Re: unsynchronous fullscreen-routine

Hi ! I'm posting to this very old thread now, because it has been very useful to me during the past weeks, and I wanted to add some performance figures since there are only estimations of remaining CPU time here. I have just done my first classical fullscreen routine (STE specific) these days (yes, ...

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