giomba/vic20-xmas-demo
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Make some automatic computation, remove hardcoded values.

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giomba 2022-12-04 20:23:44 +01:00
parent 5daf3c9b39
commit ba41f285d4
1 changed files with 15 additions and 28 deletions
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43
src/main.asm
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@ -8,6 +8,7 @@ count = $128
org $a000 org $a000
; autostart cartridge magic number
WORD coldstart WORD coldstart
WORD coldstart WORD coldstart
BYTE #$41, #$30, #$c3, #$c2, #$cd BYTE #$41, #$30, #$c3, #$c2, #$cd
@ -47,9 +48,9 @@ coldstart SUBROUTINE
sta $3b sta $3b
; set start of variables ; set start of variables
lda #<($1001 + demoend - basicdemo) lda #<($1001 + demo_end - demo_start)
sta $2d sta $2d
lda #>($1001 + demoend - basicdemo) lda #>($1001 + demo_end - demo_start)
sta $2e sta $2e
jsr clear_color_ram jsr clear_color_ram
@ -69,6 +70,7 @@ coldstart SUBROUTINE
jmp $c483 ; BASIC jmp $c483 ; BASIC
; custom hijacked command line
fake_input_line: fake_input_line:
BYTE "RUN",#$0d,#0,#0,#0 BYTE "RUN",#$0d,#0,#0,#0
@ -82,13 +84,6 @@ fake_chrin SUBROUTINE
dey dey
sty fake_current_byte sty fake_current_byte
; sei
; lda #$f2
; sta $324
; lda #$0e
; sta $325
; cli
.end_fake_chrin: .end_fake_chrin:
clc clc
rts rts
@ -104,28 +99,19 @@ clear_color_ram SUBROUTINE
bne .loop bne .loop
rts rts
print_message SUBROUTINE ; This routine does a lot of unnecessary things,
ldx #$00 ; but I added a lot of garbage things to debug it,
print: ; because it did not work as intended.
lda message,x ; In the end, the problem was elsewhere, as usual.
beq .end
sec
sbc #$40
sta 7834,x
inx
jmp print
.end:
rts
copycode SUBROUTINE copycode SUBROUTINE
sei sei
lda #0 lda #0
sta count sta count
sta count + 1 sta count + 1
lda #<basicdemo lda #<demo_start
sta srcPointer sta srcPointer
lda #>basicdemo lda #>demo_start
sta srcPointer + 1 sta srcPointer + 1
lda #$01 lda #$01
@ -153,10 +139,10 @@ copyloop:
; lenght of program to copy ; lenght of program to copy
lda count lda count
cmp #$00 cmp #<DEMO_LEN
bne copyloop bne copyloop
lda count + 1 lda count + 1
cmp #$06 cmp #>DEMO_LEN
bne copyloop bne copyloop
cli cli
@ -167,9 +153,10 @@ message:
BYTE #$0d,#$0d,"PLEASE WAIT 20 SEC",#$0d,"I'M JUST",#$0d,"AN OLD COMPUTER",#$0d,#0 BYTE #$0d,#$0d,"PLEASE WAIT 20 SEC",#$0d,"I'M JUST",#$0d,"AN OLD COMPUTER",#$0d,#0
; https://www.commodore.ca/manuals/funet/cbm/vic20/demos.basic/unexpanded/Stillenacht.prg ; https://www.commodore.ca/manuals/funet/cbm/vic20/demos.basic/unexpanded/Stillenacht.prg
basicdemo: demo_start:
.incbin "res/stillenacht.raw" .incbin "res/stillenacht.raw"
demoend: demo_end:
DEMO_LEN SET demo_end - demo_start
. = $bffc . = $bffc
jmp coldstart jmp coldstart