Make some automatic computation, remove hardcoded values.

src/main.asm

@@ -8,6 +8,7 @@ count = $128
 
     org $a000
 
+    ; autostart cartridge magic number
     WORD coldstart
     WORD coldstart
     BYTE #$41, #$30, #$c3, #$c2, #$cd
@@ -47,9 +48,9 @@ coldstart SUBROUTINE
     sta $3b
 
     ; set start of variables
-    lda #<($1001 + demoend - basicdemo)
+    lda #<($1001 + demo_end - demo_start)
     sta $2d
-    lda #>($1001 + demoend - basicdemo)
+    lda #>($1001 + demo_end - demo_start)
     sta $2e
 
     jsr clear_color_ram
@@ -69,6 +70,7 @@ coldstart SUBROUTINE
 
     jmp $c483 ; BASIC
 
+    ; custom hijacked command line
 fake_input_line:
     BYTE "RUN",#$0d,#0,#0,#0
 
@@ -82,13 +84,6 @@ fake_chrin SUBROUTINE
     dey
     sty fake_current_byte
 
-    ; sei
-    ; lda #$f2
-    ; sta $324
-    ; lda #$0e
-    ; sta $325
-    ; cli
-
 .end_fake_chrin:
     clc
     rts
@@ -104,28 +99,19 @@ clear_color_ram SUBROUTINE
     bne .loop
     rts
 
-print_message SUBROUTINE
-    ldx #$00
-print:
-    lda message,x
-    beq .end
-    sec
-    sbc #$40
-    sta 7834,x
-    inx
-    jmp print
-.end:
-    rts
-
+; This routine does a lot of unnecessary things,
+; but I added a lot of garbage things to debug it,
+; because it did not work as intended.
+; In the end, the problem was elsewhere, as usual.
 copycode SUBROUTINE
     sei
     lda #0
     sta count
     sta count + 1
 
-    lda #<basicdemo
+    lda #<demo_start
     sta srcPointer
-    lda #>basicdemo
+    lda #>demo_start
     sta srcPointer + 1
 
     lda #$01
@@ -153,10 +139,10 @@ copyloop:
 
     ; lenght of program to copy
     lda count
-    cmp #$00
+    cmp #<DEMO_LEN
     bne copyloop
     lda count + 1
-    cmp #$06
+    cmp #>DEMO_LEN
     bne copyloop
 
     cli
@@ -167,9 +153,10 @@ message:
     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
-basicdemo:
+demo_start:
     .incbin "res/stillenacht.raw"
-demoend:
+demo_end:
+DEMO_LEN SET demo_end - demo_start
 
 . = $bffc
     jmp coldstart