Created
January 3, 2019 21:37
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.const SCREEN_RAM = $0400 | |
.const COLOR_RAM = $d800 | |
.const flag = $02 | |
// --- main -------------------------------------------------------- | |
BasicUpstart2(start) | |
* = $3000 "program" | |
start: jsr initialize | |
jsr irq_setup | |
main_loop: lda flag | |
beq main_loop | |
//inc $d020 | |
lda #$00 | |
sta flag | |
jmp main_loop | |
// --- Subroutines ------------------------------------------------- | |
// Clear Screen | |
initialize: ldx #0 | |
lda #$0 | |
!: sta SCREEN_RAM+$000,x | |
sta SCREEN_RAM+$0ff,x | |
sta SCREEN_RAM+$1ff,x | |
sta SCREEN_RAM+$2ff,x | |
dex | |
bne !- | |
lda #00 | |
sta $d020 | |
sta $d021 | |
// Initialize varibles | |
lda #$00 | |
sta flag | |
rts | |
// --- irq routines ------------------------------------------------ | |
.macro set_irq(addr, row_lo, row_hi){ | |
.if (!row_hi) { | |
lda $d011 // high bit of raster line | |
and $7f | |
sta $d011 | |
} | |
else { | |
lda $d011 | |
ora #$80 | |
sta $d011 | |
} | |
lda row_lo // low byte of raster line | |
sta $d012 | |
lda #<addr | |
sta 788 | |
lda #>addr | |
sta 789 | |
} | |
.const raster_row1 = 100 | |
.const raster_row2 = 150 | |
.const raster_row3 = 200 | |
irq_setup: sei | |
lda #$7f | |
sta $dc0d | |
sta $dd0d | |
lda #$00 | |
sta $dc02 | |
lda #$01 | |
sta $d01a | |
set_irq(irq01, raster_row1, false) | |
cli | |
rts | |
/* IRQ01 - Logo */ | |
irq01: lda #$01 | |
sta $d020 | |
sta $d021 | |
set_irq(irq02, raster_row2, false) | |
!out: asl $d019 | |
jmp $ea81 | |
/* IRQ02 - Cloud */ | |
irq02: lda #$02 | |
sta $d020 | |
sta $d021 | |
set_irq(irq03, raster_row3, false) | |
!out: asl $d019 | |
jmp $ea81 | |
/* IRQ03 - Scroll */ | |
irq03: lda #$03 | |
sta $d020 | |
sta $d021 | |
set_irq(irq01, raster_row1, false) | |
lda #$00 | |
sta flag | |
!out: asl $d019 | |
jmp $ea81 |
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