75 lines
804 B
ArmAsm
75 lines
804 B
ArmAsm
;
|
|
; vbl.s
|
|
; colourgo
|
|
;
|
|
; Created by Jeremy Rand on 2017-07-19.
|
|
; Copyright © 2017 Jeremy Rand. All rights reserved.
|
|
;
|
|
|
|
|
|
|
|
.export _vblWait, _vblWaitNon2c, _vblWait2c, _vblInit2gs
|
|
.export _gVblWait, _vblIRQCallback
|
|
|
|
|
|
.include "apple2.inc"
|
|
|
|
|
|
RDVBLBAR := $C019
|
|
|
|
|
|
.proc _vblWait
|
|
jmp (_gVblWait)
|
|
.endproc
|
|
|
|
.proc _vblInit2gs
|
|
lda #$fe
|
|
sta compType
|
|
.endproc
|
|
|
|
|
|
.proc _vblWaitNon2c
|
|
lda compType
|
|
@L1:
|
|
cmp RDVBLBAR
|
|
bpl @L1
|
|
@L2:
|
|
cmp RDVBLBAR
|
|
bmi @L2
|
|
|
|
rts
|
|
.endproc
|
|
|
|
|
|
.proc _vblIRQCallback
|
|
pha
|
|
lda #$0
|
|
sta vbl2cByte
|
|
pla
|
|
rts
|
|
.endproc
|
|
|
|
|
|
.proc _vblWait2c
|
|
lda #$ff
|
|
sta vbl2cByte
|
|
|
|
@L1:
|
|
lda vbl2cByte
|
|
bne @L1
|
|
|
|
rts
|
|
.endproc
|
|
|
|
|
|
.data
|
|
|
|
_gVblWait:
|
|
.BYTE $0, $0
|
|
|
|
compType:
|
|
.BYTE $7e
|
|
|
|
vbl2cByte:
|
|
.BYTE $00
|