;
;
; SOME AMIGA-LIKE GROWING/SHRINKING RASTERBARS FOR THE C65.
; USE THEM WITH THE "BORDER-DEMO" BASIC LOADER
;
; WITH SPECIAL THANKS TO THOMAS HECHELHAMMER FOR FIGURING OUT
; WHERE TO PUT THIS STUFF IN THE C65 MEMORY FOR GETTING IT TO
; WORK CORRECTLY ;-)))))))
;
; COPYRIGHT (C) 1997 STEPHAN KLEINERT
; SPREAD THIS AS FAR AS YOU LIKE, BUT LEAVE IT AS IT IS...
;
; LEMON@GROMIT.INKA.DE
;
ORG $1C00

JMP INIT

:IRQ=$0314

:OLDIRQ
B 0,0

:MERK
B 0


:INIT

SEI                        ; DISABLE IRQ

LDX IRQ
LDY IRQ+1
STX OLDIRQ                 ; SAVE OLD IRQ VECTOR
STY OLDIRQ+1
LDX #<NEWIRQ               ; INSTALL NEW IRQ ROUTINE
LDY #>NEWIRQ
STX IRQ
STY IRQ+1

LDA #$F8                   ; END OF SCREEN
STA $D012
LDA $D011
AND #$7F
STA $D011

LDA #$81
STA $D01A                  ; ENABLE RASTER IRQ

LDA #$00
STA $D020
LDA #$04                   ; SAVE BAR WIDTH
STA MERK                   ;
CLI
RTS

:NEWIRQ

LDA $D019                  ; INTERRUPT FROM CIA?
STA $D019
BMI VICIRQ                 ; NO -----> DO RASTER STUFF

CLI
JMP (OLDIRQ)               ; JA   ---> Ã65-ÁAL

:VICIRQ
LDA $D012
CMP #$F8
BCS NIXDA                  ; BELOW TEXT AREA? ---> DO NOTHING

CLC
ADC MERK
STA $D012

LDY #$FC
:WARTEN                    ; DELAY
DEY
BNE WARTEN

INC $D020                  ; NEW SCREEN COLOUR
INC $D021
JMP IRQEND                 ; DO C65 IRQ


:NIXDA                     ; PAINT IT BLACK
LDA #$00
STA $D020
STA $D021

LDA #$32
STA $D012
JMP (OLDIRQ)







:IRQEND                    ; NOW SOME FUNKY EXTENDED 4502 OPCODES ;))

PLA

B $5B ; ÔÁÂ
B $FB ; ÐÌÚ
B $7A ; ÐÌÙ
B $FA ; ÐÌØ

PLA

RTI