initial commit

2026-07-15 21:31:51 +02:00
commit 0fb584bcd7
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+; -----------------------------------------------------------
+; main.asm - RABBIT SCOOTER for the C64
+;   port of the rabbitroller Game & Watch style LCD game:
+;   rabbits hop toward you on a five-lane road, dodge them
+;   on your scooter - a rabbit reaching your lane is a miss,
+;   one passing in another lane is a point; 3 misses = over
+;
+; Files:
+;   defs.asm    - constants, zero page, macros
+;   title.asm   - title screen: demo rabbits + press fire
+;   play.asm    - the game itself
+;   over.asm    - game over box + retry
+;   common.asm  - shared routines, input, rabbit positioning
+;   tables.asm  - perspective / speed tables (assembly-time)
+;   sprites.asm - sprite art (scooter, small + big rabbits)
+;
+; Build: acme -f cbm -o rabbit.prg main.asm
+; -----------------------------------------------------------
+
+!to "rabbit.prg", cbm
+
+* = $0801
+
+; ---- BASIC stub: 10 SYS 2064 ----
+; so after LOAD"*",8,1 it's enough to type RUN
+!byte $0c, $08          ; address of next line
+!byte $0a, $00          ; line number: 10
+!byte $9e               ; SYS token
+!byte $20, $32, $30, $36, $34   ; " 2064"
+!byte $00               ; end of line
+!byte $00, $00          ; end of program
+
+* = $0810                ; = 2064 in decimal
+
+!src "defs.asm"
+
+start:
+    sei                  ; no KERNAL IRQ - raster polling must not jitter
+
+    ; LCD look: black bezel border, pale screen, black artwork
+    lda #BLACK
+    sta BORDER
+    lda #LGREY
+    sta BG
+
+    ; sprites: all black, hires, in front of the characters
+    ldx #7
+sprcol:
+    lda #BLACK
+    sta SPR_COL,x
+    dex
+    bpl sprcol
+    lda #0
+    sta SPR_EN
+    sta SPR_MC
+    sta SPR_PRIO
+    sta SPR_MSBX
+    sta SPR_XEX
+    sta SPR_YEX
+    sta framectr
+    sta fheld
+
+!ifdef AUTOPLAY {        ; test builds boot straight into the game
+    jsr play_init
+} else {
+    jsr title_init
+}
+
+; ============================================================
+; main loop - one state update per PAL frame, synced to the
+; raster beam in the lower border
+; ============================================================
+main:
+    jsr wait_frame
+    inc framectr
+    jsr rand8            ; stir the RNG once per frame
+    jsr call_update
+    jmp main
+
+call_update:
+    jmp (updvec)         ; each update runs exactly one frame, ends with rts
+
+; ---- wait for raster line RAS_SYNC (leave it first, so a
+; fast update cannot run twice in the same frame) ----
+wait_frame:
+    lda RASTER
+    cmp #RAS_SYNC
+    beq wait_frame
+wf_hit:
+    lda RASTER
+    cmp #RAS_SYNC
+    bne wf_hit
+    rts
+
+; ============================================================
+; sprite art first: it must stay below $1000, where the VIC
+; would see the character ROM shadow instead of our RAM
+; ============================================================
+!src "sprites.asm"
+!if * > $1000 {
+    !error "sprite data ran into the char ROM shadow at $1000"
+}
+
+; ============================================================
+; the states and everything they share
+; ============================================================
+!src "title.asm"
+!src "play.asm"
+!src "over.asm"
+!src "common.asm"
+!src "tables.asm"