| | 8bitforever
Account closed
Registered: Oct 2009
Posts: 48 |
Howto flickerfree and moving rasterbar ?
<Post edited by moderator on 20/10-2009 01:24>
Making a perfect stable, flickerfree and moving rasterbar is harder than I thought.
Why and which changes are needed to the code below to fulfill my dream about the flickerfree rasterbar?
The code is based on http://www.ffd2.com/fridge/vic/stableraster.txt.
Acme code ready to compile:
!to "doubleirqrasterbar1.prg",cbm
*= $0800
!byte $00,$0c,$08,$0a,$00,$9e,$33,$32,$37,$36,$38,$00,$00,$00,$00
raspos = $00
maxpos = $7c
*= $8000 ;Assemble to $8000
cld ;Clear Decimal Mode
sei ;Disable IRQ's
lda #$1f ;Disable CIA IRQ's
sta $dc0d
sta $dd0d
; lda #<nmi ;Install NMI into
; ldx #>nmi ;Hardware NMI and
; sta $fffa ;RESET Vectors
; sta $fffc
; stx $fffb
; stx $fffd
lda #<irq1 ;Install RASTER IRQ
ldx #>irq1 ;into Hardware
sta $0314 ;Interrupt Vector
stx $0315
; lda #$35 ;Set MMU to RAM at
; ldx #$ff ;$a000-$bfff and
; sta $01 ;$e000-$ffff
; txs ;Clear the STACK
lda #$01 ;Enable RASTER IRQ
ldx #$1b ;High bit of RASTER
ldy #$34 ;compare register
sta $d01a ;and RASTER IRQ to
stx $d011 ;line $34
sty $d012
;NOTE double IRQ
;cannot be on or
;around a BAD LINE!
;(Fast Line)
lda #$0e ;Set Background
ldx #$06 ;and Border colors
ldy #$00 ;to default and
sta $d020 ;turn off sprites
stx $d021
sty $d015
jsr clrscreen
jsr clrcolor
; jsr printtext
asl $d019 ;Ack any previous
lda $dc0d ;IRQ's
lda $dd0d
cli ;Renable IRQ's
jmp * ;Endless Loop
irq1
sta reseta1 ;Preserve A,X and Y
stx resetx1 ;Registers
sty resety1 ;VIA self modifying
;code
;(Faster than the
;STACK is!)
lda #<irq2 ;Set IRQ Vector
ldx #>irq2 ;to point to the
ldy #$35 ;next part of the
sta $0314 ;Stable IRQ
stx $0315 ;ON NEXT LINE!
sty $d012
asl $d019 ;Ack RASTER IRQ
tsx ;We want the IRQ
cli ;To return to our
nop ;endless loop
nop ;NOT THE END OF
nop ;THIS IRQ!
nop
nop ;Execute nop's
nop ;until next RASTER
nop ;IRQ Triggers
nop
nop ;2 cycles per
nop ;instruction so
nop ;we will be within
nop ;1 cycle of RASTER
nop ;Register change
; nop ;<--- remove 1 NOP for PAL
irq2
txs ;Restore STACK
;Pointer
ldx #$08 ;Wait exactly 1
dex ;lines worth of
bne *-1 ;cycles for compare
bit $ea ;Minus compare
nop ;cycles
; nop ;<--- remove 1 NOP for PAL
lda #$35 ;RASTER change yet?
cmp $d012
beq start ;If no waste 1 more
;cycle
start
ldx raspos
cpx #maxpos
beq setrastup
inx
stx raspos
cpx #maxpos
bne rasterbarctrl
setrastup
ldx #$00
stx raspos ;Reset raster positon to
;zero if maximum has been reached.
rasterbarctrl
ldx raspos
ldy rastmov,x ;Wait for rasterline $3D-$96 at $D012
wait cpy $d012
bne wait
;rasterbar
ldx #$00
copy11 ldy rastime,x
dey
bne *-1
lda coloursr,x
sta $d020
sta $d021
inx
cpx #$10
bne copy11
lda #<irq3 ;Set IRQ to point
ldx #>irq3 ;to subsequent IRQ
ldy #$b8 ;at line $68
sta $0314
stx $0315
sty $d012
asl $d019 ;Ack RASTER IRQ
lda #$00 ;Reload A,X,and Y
reseta1 = *-1 ;registers
ldx #$00
resetx1 = *-1
ldy #$00
resety1 = *-1
; rti ;Return from IRQ
jmp $ea31
irq3
sta reseta2 ;Preserve A,X,and Y
stx resetx2 ;Registers
sty resety2
ldx #$0a ;Waste some more
dex ;time so effect
bne *-1 ;can be seen
nop
; lda #$0e ;More colors
; ldx #$06
; nop:nop
; sta $d021 ;Cool! subsequent
; stx $d021 ;IRQ's are also
;stable :-)
;Unless you are
;running realtime
;code :-)
ldy #$18 ;Waste time so this
dey ;IRQ does not try
bne *-1 ;to reoccur on the
;same line!
lda #<irq1 ;Reset Vectors to
ldx #>irq1 ;first IRQ again
ldy #$34 ;at line $34
sta $0314
stx $0315
sty $d012
asl $d019 ;Ack RASTER IRQ
lda #$00 ;Reload A,X,and Y
reseta2 = *-1 ;registers
ldx #$00
resetx2 = *-1
ldy #$00
resety2 = *-1
; rti ;Return from IRQ
jmp $ea81
;Pound RESTORE to
;get back to Turbo
nmi
asl $d019 ;Ack all IRQ's
lda $dc0d
lda $dd0d
lda #$81 ;reset CIA 1 IRQ
ldx #$00 ;remove raster IRQ
ldy #$37 ;reset MMU to roms
sta $dc0d
stx $d01a
sty $01
ldx #$ff ;clear the stack
txs
cli ;reenable IRQ's
jmp $9000 ;back to Turbo
clrscreen
lda #$20 ;Clear the screen
ldx #$00
clrscr sta $0400,x
sta $0500,x
sta $0600,x
sta $0700,x
dex
bne clrscr
rts
clrcolor
lda #$03 ;Clear color memory
ldx #$00
clrcol sta $d800,x
sta $d900,x
sta $da00,x
sta $db00,x
dex
bne clrcol
rts
printtext
lda #$16 ;C-set = lower case
sta $d018
ldx #$00
moretext lda text1,x
bpl lower ;upper case ?
eor #$80 ;yes
bne lower+2
lower and #$3f ;lower case
sta $0450,x
inx
cpx #$78
bne moretext
exit rts
text1
!scr "Stable Raster IRQ sourc"
!scr "e (PAL/NTSC) "
!scr "All Code by Fungus 1996"
!scr " "
!scr "Feel free to use and mo"
!scr "dify this code :)"
;------------------------------------------------------------------------------- -
;raster data
;------------------------------------------------------------------------------- -
rastime
!byte $08,$08,$08,$08,$08,$08,$08,$01
!byte $08,$08,$08,$08,$08,$08,$08,$01
coloursr
!byte $0b,$0b,$0c,$0c,$0f,$0f,$0d,$0d
!byte $0d,$0f,$0f,$0c,$0c,$0b,$0b,$00
rastmov
!byte $3D,$3D,$3E,$3E,$3F,$3F,$40,$40,$41,$42,$43,$44,$45,$46,$47,$48
!byte $49,$4A,$4C,$4E,$50,$52,$54,$56,$58,$5A,$5C,$5E,$60,$62,$64,$66
!byte $68,$6A,$6C,$6E,$70,$72,$74,$76,$78,$7A,$7C,$7E,$80,$82,$84,$86
!byte $88,$8A,$8C,$8E,$8F,$90,$91,$92,$93,$94,$94,$95,$95,$96,$96,$95
!byte $95,$94,$94,$93,$93,$92,$91,$90,$8F,$8E,$8D,$8D,$8B,$89,$87,$85
!byte $83,$81,$7F,$7D,$7B,$79,$77,$75,$73,$71,$6F,$6D,$6B,$69,$67,$65
!byte $63,$61,$5F,$5D,$5B,$59,$57,$55,$53,$51,$4F,$4D,$4B,$49,$48,$47
!byte $46,$45,$44,$43,$42,$41,$40,$40,$3F,$3F,$3E,$3E
|
|
... 71 posts hidden. Click here to view all posts....
|
| | chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:Magervalp, see my code below that uses kernal IRQ vector instead of hardware IRQ vector.
Perfectly stable moving flickerfree rasterbar based on the stable raster code
except it isnt "perfectly stable" at all. you just pushed the flickering part into the borders. this is not bad per se for a simple rasterbar like this, but then again you dont need all that stable raster code at all for it =P |
| | MagerValp
Registered: Dec 2001
Posts: 1078 |
This reminds me of a quote on slashdot:
"Tell me, is there any kind of physical sensation associated with having an abnormally low IQ? Is there like a numbness or heaviness inside your head? Or is the affliction completely transparent to the sufferer?" |
| | Voltage
Account closed
Registered: Jul 2008
Posts: 14 |
@MagerValp: I'm oblivious. What does that mean? |
| | Skate
Registered: Jul 2003
Posts: 494 |
@Voltage: Shift raster timings a little bit and you'll get it. I didn't test 8bitforever's code but if you use stable raster routine without understanding it or at least without obeying some simple rules, it won't be stable anymore. Usually rules are broken by trying to change raster interrupt entry positions or adding/removing some irqs. |
| | 8bitforever
Account closed
Registered: Oct 2009
Posts: 48 |
Groepaz, the stable rastercode is going to be used for other things and I should not have used the word perfectly stable.
I would like to give a big special thanks to those of you
how actually contributed with code in their comments:
Jan, Jackasser and Skate.
|
| | chatGPZ
Registered: Dec 2001
Posts: 11386 |
"the stable rastercode is going to be used for other things and I should not have used the word perfectly stable."
you should have tried to understand how the code works in the first place. if you just blindly modify it like you did, then you can just aswell omit it completely, there is no difference. |
| | Street Tuff
Registered: Feb 2002
Posts: 88 |
now after you managed to code this hard routine i would like to be pleased if you code a nufli displayer for us.
regards
tuff |
| | Voltage
Account closed
Registered: Jul 2008
Posts: 14 |
Quote: @Voltage: Shift raster timings a little bit and you'll get it. I didn't test 8bitforever's code but if you use stable raster routine without understanding it or at least without obeying some simple rules, it won't be stable anymore. Usually rules are broken by trying to change raster interrupt entry positions or adding/removing some irqs.
Yeah I get the raster bits.
My comment was an attempt at a joke. As in... "Or is the affliction completely transparent to the sufferer?" |
| | cavey
Registered: Jul 2002
Posts: 68 |
fuck. And I thought I was an idiot for reading ripping and disecting a sprite routine many many years ago >_< |
| | 8bitforever
Account closed
Registered: Oct 2009
Posts: 48 |
Cavey,
8 hours ago I coded my own four split rasterbar with moving colors within. The colors move with diffrent timing.
It´s all stable and flickerfree. I´m doing progress. :-) |
| Previous - 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 - Next | |
