Hi,
On 12/20/20 1:16 AM, Laurent Sallafranque wrote:
I post here my current search for sharing with you.
I've worked on a memory address that is not used by the videl for
now : the videl address counter.
At least, 2 programs write into it : killing impact and pinball dreams.
By adding only 3 lines of code into videl.c, I manage to remove
(partially for now) the screen garbage for these 2 programs.
Now, the screens are correctly rendered and the games are playable.
>
With killing impact, there's another problem with vertical display
(I think the screen may be doubled on real Falcon ?)
With Pinball Dreams, the game change twice the counter address : 1st
time for score display and 2nd time for the game itself (that's why
there's still garbage at bottom of the table now, the screen should
be displayed lower (the upper part of the screen should display the
score panel).
For now, you can consider it as a proof of concept.
It renders better the 2 games,
Verified.
but that's not perfect.
No, it breaks Doug's Bad Mood game 3D rendering.
That shows just garbage (area above that renders
fine).
And when you quit the games, the hack still operate, but it should not.
The good way to solve it would be to improve thye videl
The bad way (but with a good result) would just consist to add a new
variable to videl, reset it to 0 at the brginning of a VBL and if a
program changes the counter, set this variable to 1. like this, the
hack would work cleanly.
Should I complete the temporary hack (for better rendering but not
perfect) or shouldn't be add such a bad hack that may be hard to
understand later is someone works on videl later (except if we add a
ton of comments to explain it).
I think cleanly implemented hacks that are clearly
marked in code with TODO comments and listed in
doc/todo.txt are fine, if they don't break things.
In any case it should wait after bug fix release.
- Eero
I'm interrested in your point of view.
Regards
Laurent
The proof of concept patch : diff -u
diff --git a/src/falcon/videl.c b/src/falcon/videl.c
index cf5ce874..e4019413 100644
--- a/src/falcon/videl.c
+++ b/src/falcon/videl.c
@@ -942,6 +942,10 @@ bool VIDEL_renderScreen(void)
bool change = false;
Uint32 videoBase = VIDEL_getVideoramAddress();
+ Uint32 videocounter = (IoMem_ReadByte(0xff8205)<<16) +
(IoMem_ReadByte(0xff8207)<<8) + IoMem_ReadByte(0xff8209);
+
+ if (videocounter != 0)
+ videoBase = videocounter;
if (vw > 0 && vw != videl.save_scrWidth) {
LOG_TRACE(TRACE_VIDEL, "Videl : width change from
%d to %d\n", videl.save_scrWidth, vw);