Blit o this, Blit o that

More fun and games with the blitter tonight, and mostly a success too.  Painting a 32×32 image into a 320×200 screen, getting the painting to not overwrite the background image, stuff like that.  In the process got to learn a lot more about the blitter and experienced some interesting effects which it may be nice to play with when I get to write something a bit more substantial 🙂

Tried my hand at blitter fading too, actually got it to work eventually as well! alas it seems to cane the system and there simply isn’t enough bandwidth to do what I had hoped.  Although as is the way I have had an idea or two how I may be able to improve the effect I was after and speed the process up too!  But that is something to play with tomorrow 🙂

As well as some full screen scrolling I hope too.

Evil apparently!

Second day of trying to get my head around the blitter on my Jag.  Not going as well as I hoped and much head scratching was being had.  Thankfully chatting on IRC with some helpful fellow Jag coders got me sorted.  Some handy snippets of blitter set-up code, commedy drivel and me finally spotting a rogue BSS section in one of my source files soon had me right.

Apparently the use of and users of the blitter are “Evil” and the cause for much suffering according to some 🙂

So far I am just using it to clear a chunk of RAM, tomorrow post work should see more progress in the blitter side of the force.  Hopefully then I can start bringing all these bits and pieces together and make something prettyish to look at 🙂

Getting there

I was about to go to bed when I thought I would have a quick poke at my Jaguar code and run my memory dumper against a known good object list.  The results? mine matched (as much as it could given they resided in different parts of RAM and hence had different link data etc).. So, why is it that mine didn’t work and this other did.

My first thoughts were that perhaps the two branches I had put at the start of my list were in-correct, they should be there I recall to keep the hardware happy, but this other list didn’t have them and worked.  So I skipped the branches and fed the OP the address of the raw meat of the list.  OUTPUT! although not what I expected, some garbled lines, and not a smidgeon of anything resembling the bitmap it was supposed to. Hmmm more pondering.

Inspiration came and a glance at the developers manual to confirm.. 16 byte boundary in 64 bit RAM.. Hmmmm  A few tweaks here and there and I tried again, dumping the list from its full head including branches but ensuring that the meaty goodness resided only on a 16 byte boundary.  The dump now showed a row of zeros between the last branch and the bitmap object and the monitor showed the bitmap!  EUREKA!  success at last.  It even looks like the adjustments for start of display worked too!  I am most pleased with myself.

Now I just need to work on ensuring that bitmap object reside correctly and that the prior object is aware of this for link generation! more complexity, or waste a bit of RAM.. for now I think I might just go for the more wasteful route, its only a few bytes and I have 2MB to play with 😀


With living in my flat, storing my bike was a bit of an issue.  I was a little excited when I bought the place to find out that they had bike sheds planned out in the carpark.  I envisioned some sturdy locakable box type things.  Alas no, just the crappiest of crappy bits of metal bolted to the floor with some tin roofed wood thing around them :/  If you didn’t end up with your wheels bent to buggery by them I am sure anyone wanting your bike would just unbolt the bike mount from the floor and carry it off.

So my bike has lived in my spare room since I moved here.  Which is less than optimal given it pretty much renders the spare room less than functional if I have more than one guest (and I hate giving up my bed!)

Thankfully a visit to Evans Cycles gave me an answer.. a TopPeak OneUp!  I have had it for a while but usual lack of motivation meant it has sat in its rather nice box for a long time.  With an impending visit from a couple of friends I need to get the room sorted.  Armed with my stud/metalwork/mains cable finder I set about putting it up.. not too difficult and it seems to hold the bike quite well.. was surprised mike bike actually weighs in at 15KGs, the OneUp states no more than 16KG so I am just in the clear 🙂

Anyone looking to get one they are not too expensive and are very well built.

Just hope my drilling holds 🙂

24 hours! oh crap

It would seem I am, or have involuentarily entered a 24 hour coding competition in April when I goto France for Atari Connexion 2011.  This could be painful!  I have been assured that an Atari coding hangover is something to be proud of.. I suspect they may be forgetting I am driving everyone home too 🙂  Guess I will sleep on Sunday 😀

Best get more of my code finished then I guess 🙂  should be fun even if I produce nothing amazing (which I won’t, will have to try and get a youtube clip up or something after the fact.. assuming it runs 😀 )