first commit

main.s

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+; Amiga 500 Email Game - Main Entry Point
+; ---------------------------------------------------------------------------
+
+    INCDIR  "c:/Users/capitano/Documents/giochino/"
+    INCLUDE "custom.i"
+
+    ; SECTION Code,CODE_C
+
+    ; Load address for the game (must match bootblock)
+    ORG     $20000
+
+START:
+    ; Initialize Stack Pointer to safe area (64KB above game start)
+    ; Stack grows downward, so we put it well above our code
+    lea     $30000,sp
+
+    ; Don't take over the system completely - stay system friendly
+    ; move.l  4.w,a6          ; ExecBase
+    ; jsr     -132(a6)        ; Forbid (disable multitasking)
+
+    ; Save old view
+    lea     CUSTOM,a6
+    move.w  INTENAR(a6),d0
+    or.w    #$8000,d0
+    move.w  d0,OldIntEna
+    move.w  DMACONR(a6),d0
+    or.w    #$8000,d0
+    move.w  d0,OldDmaCon
+
+    ; Disable all interrupts and DMA
+    move.w  #$7FFF,INTENA(a6)
+    move.w  #$7FFF,DMACON(a6)
+    move.w  #$7FFF,INTREQ(a6)
+
+    ; Initialize Subsystems
+    bsr     InitGraphics
+    bsr     InitGameLogic
+
+    ; Enable DMA for Copper, Bitplanes, Blitter
+    move.w  #$83C0,DMACON(a6) ; Set DMAEN, BPLEN, COPEN, BLTEN
+
+MAIN_LOOP:
+    ; Wait for vertical blank
+    bsr     WaitVBlank
+
+    ; 1. Read Input
+    bsr     ReadInput
+
+    ; 2. Update Game Logic
+    bsr     UpdateGame
+
+    ; 3. Check for Exit (Left Mouse Button for now)
+    btst    #6,CIAA
+    bne.s   MAIN_LOOP
+
+EXIT:
+    ; Restore System
+    lea     CUSTOM,a6
+    move.w  #$7FFF,DMACON(a6)
+    move.w  #$7FFF,INTENA(a6)
+    
+    move.w  OldDmaCon,DMACON(a6)
+    move.w  OldIntEna,INTENA(a6)
+
+    ; Enable multitasking
+    ; move.l  4.w,a6
+    ; jsr     -138(a6)        ; Permit
+
+    moveq   #0,d0
+    rts
+
+; ---------------------------------------------------------------------------
+; Helper Routines
+; ---------------------------------------------------------------------------
+
+WaitVBlank:
+    lea     CUSTOM,a6
+.wait:
+    move.l  $04(a6),d0
+    and.l   #$1ff00,d0
+    cmp.l   #300<<8,d0
+    bne.s   .wait
+    rts
+
+; ---------------------------------------------------------------------------
+; Included Modules
+; ---------------------------------------------------------------------------
+    INCLUDE "graphics.s"
+    INCLUDE "game_logic.s"
+    INCLUDE "input.s"
+    INCLUDE "data.s"
+
+; ---------------------------------------------------------------------------
+; Data
+; ---------------------------------------------------------------------------
+    ; SECTION Data,DATA_C
+
+OldIntEna:  dc.w    0
+OldDmaCon:  dc.w    0
+
+    END