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Trash
Registered: Jan 2002
Posts: 122 |
Why does this work?
start
sei
lda #$50
cmp $d012
bne *-3
ldx #128
loop
lda $d012
and #7
ora #16
sta $d011
inc $d021
dex
bne loop
jmp start
Feel free to add some sprites above the rasters and the colorbars will time themself. How and why does this work? |
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HCL
Registered: Feb 2003
Posts: 728 |
Common Puntus, why do you have to show off your lack of skills this way? If you had a life you wouldn't need to ask this ;).
You're doing some sort of FLI-timing when you write to D011, which always results in a "stable raster". If you put moving sprites on top of it you'll see a rather unstable FLI-bugs on the left depending on how many sprites are on that particular line. |
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trident
Registered: May 2002
Posts: 91 |
Doesn't writing to $d011 often result in timed code becuase of CPU delays? I seem to remember seeing similar things with FLI routines. |
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Trash
Registered: Jan 2002
Posts: 122 |
Quote: Common Puntus, why do you have to show off your lack of skills this way? If you had a life you wouldn't need to ask this ;).
You're doing some sort of FLI-timing when you write to D011, which always results in a "stable raster". If you put moving sprites on top of it you'll see a rather unstable FLI-bugs on the left depending on how many sprites are on that particular line.
Ofcoz I've got to show my bad skills, especially when the cyclecount in the routine above can exceed the number of free cycles on a normal badline and still be timed in row for row.
BTW, 81% isn't enough you should work to get Tsunami to the 100% marker before answering dumb questions like mine.. ;-) |
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Oxidy
Account closed
Registered: Mar 2003
Posts: 80 |
Trash: Next year you can't bail on Floppy! I was expecting some turkish pepper data, and had to settle with other less appealing alternatives. |
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Trash
Registered: Jan 2002
Posts: 122 |
Quote: Trash: Next year you can't bail on Floppy! I was expecting some turkish pepper data, and had to settle with other less appealing alternatives.
No worrys, I'll bring the turks to LCP and I'll guess you'll be there and therefore I find the short-term problem solved, Floppy will be a long-term problem as I'm in the middle of buying a house (can you spell d-a-t-a-h-e-l-g or does Vodka have a monopoly on that?). |
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Cybernator
Registered: Jun 2002
Posts: 154 |
Pretty simple. When you write to $d011, VIC takes over the bus until it finishes reading the chars. So no matter at which cycle you access $d011 (as long as it's at the cycles where VIC halts the CPU due to badline), DEX:BNE LOOP will always go after VIC has freed the bus. |
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Oxidy
Account closed
Registered: Mar 2003
Posts: 80 |
Quote: No worrys, I'll bring the turks to LCP and I'll guess you'll be there and therefore I find the short-term problem solved, Floppy will be a long-term problem as I'm in the middle of buying a house (can you spell d-a-t-a-h-e-l-g or does Vodka have a monopoly on that?).
Don't forget Axis of Evil 2005, 3-4 weeks before LCP. As always at Björnön/Västerås. Until next time I'll prepare a bottle of my special brew. |
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Sledge
Registered: Sep 2003
Posts: 102 |
Quote: No worrys, I'll bring the turks to LCP and I'll guess you'll be there and therefore I find the short-term problem solved, Floppy will be a long-term problem as I'm in the middle of buying a house (can you spell d-a-t-a-h-e-l-g or does Vodka have a monopoly on that?).
Datahelg is a fine way to meet up. It inspired me and Speedball to arrange Micromeeting ourselves. And a Micromeeting with Vodka through IRC, having a "one-man-datafylla", is perhaps even better ;)
If you own a house then it's obvious you have to arrange small meetings.. unavoidable.. totally :) |
