; Graphics Module
; ---------------------------------------------------------------------------

    INCDIR  "c:/Users/capitano/Documents/giochino/"
    INCLUDE "custom.i"
    
    ; XDEF    InitGraphics
    ; XDEF    CopperList
    ; XDEF    Bitplane1
    ; XDEF    ClearScreen
    ; XDEF    DrawText
    ; XDEF    DrawChar

    ; XREF    Font8x8

    ; SECTION Code,CODE_C

InitGraphics:
    lea     CUSTOM,a6

    ; 1. Setup Bitplanes
    move.w  #$1200,BPLCON0(a6)  ; 1 Bitplane, Color on
    move.w  #0,BPLCON1(a6)      ; Scroll 0
    move.w  #0,BPLCON2(a6)      ; Priority 0
    move.w  #0,BPL1MOD(a6)      ; Modulo 0
    
    ; Setup Display Window
    move.w  #$2c81,DIWSTRT(a6)
    move.w  #$2cc1,DIWSTOP(a6)
    move.w  #$0038,DDFSTRT(a6)
    move.w  #$00d0,DDFSTOP(a6)

    ; 2. Setup Copper List
    lea     CopperList,a0
    move.l  a0,COP1LCH(a6)
    move.w  #0,COPJMP1(a6)

    ; 3. Setup Bitplane Pointers
    lea     Bitplane1,a1
    move.l  a1,d0
    lea     CopperBplPtr,a0
    swap    d0
    move.w  d0,2(a0)
    swap    d0
    move.w  d0,6(a0)

    ; 4. Clear Screen
    bsr     ClearScreen

    rts

ClearScreen:
    lea     Bitplane1,a0
    move.w  #(40*256)/4-1,d0 ; Longwords
.loop:
    move.l  #0,(a0)+
    dbf     d0,.loop
    rts

; DrawText
; d0 = X, d1 = Y, a0 = String
DrawText:
    movem.l d0-d3/a0-a2,-(sp)
    
    ; d0 = Initial X (keep in d3 for CR)
    move.w  d0,d3
    
    ; Initial Setup
    bsr     .calcAddr

.charLoop:
    move.b  (a0)+,d2    ; Get char
    beq.s   .done       ; Null terminator?

    cmp.b   #10,d2      ; Newline (LF)?
    beq.s   .newline
    cmp.b   #13,d2      ; CR?
    beq.s   .carriageReturn

    sub.b   #32,d2      ; ASCII adjustment
    ext.w   d2
    
    ; Get font address
    lea     Font8x8,a2
    lsl.w   #3,d2       ; * 8
    add.w   d2,a2

    ; Draw 8 lines of the char
    move.b  (a2)+,(a1)
    move.b  (a2)+,40(a1)
    move.b  (a2)+,80(a1)
    move.b  (a2)+,120(a1)
    move.b  (a2)+,160(a1)
    move.b  (a2)+,200(a1)
    move.b  (a2)+,240(a1)
    move.b  (a2)+,280(a1)

    addq.w  #1,a1       ; Next char pos
    bra.s   .charLoop

.newline:
    addq.w  #1,d1       ; Increment Y (lines)
    bsr     .calcAddr   ; Recalculate address (Resets X to d3)
    bra.s   .charLoop

.carriageReturn:
    ; Just reset X to d3, keep Y
    bsr     .calcAddr
    bra.s   .charLoop

.done:
    movem.l (sp)+,d0-d3/a0-a2
    rts

.calcAddr:
    lea     Bitplane1,a1
    move.l  d1,d4       ; Copy Y
    mulu    #320,d4     ; Y * 320
    add.l   d4,a1
    add.w   d3,a1       ; Add Initial X
    rts

; DrawChar
; d2 = Char code, d0 = X, d1 = Y
DrawChar:
    movem.l d0-d3/a0-a2,-(sp)
    lea     Bitplane1,a1
    mulu    #320,d1
    add.l   d1,a1
    add.w   d0,a1

    sub.b   #32,d2
    ext.w   d2
    lea     Font8x8,a2
    lsl.w   #3,d2
    add.w   d2,a2

    move.b  (a2)+,(a1)
    move.b  (a2)+,40(a1)
    move.b  (a2)+,80(a1)
    move.b  (a2)+,120(a1)
    move.b  (a2)+,160(a1)
    move.b  (a2)+,200(a1)
    move.b  (a2)+,240(a1)
    move.b  (a2)+,280(a1)

    movem.l (sp)+,d0-d3/a0-a2
    rts

    ; SECTION Data,DATA_C

    CNOP 0,4
CopperList:
    DC.W    COLOR00, $0333  ; Background
    DC.W    COLOR01, $0FF0  ; Text

CopperBplPtr:
    DC.W    BPL1PTH, $0000
    DC.W    BPL1PTL, $0000

    ; Desk Top
    DC.W    $2c07, $FFFE
    DC.W    COLOR00, $0642

    ; Monitor Area (Lines 80-200 approx)
    DC.W    $5007, $FFFE
    DC.W    COLOR00, $0000

    ; Desk Bottom
    DC.W    $D007, $FFFE
    DC.W    COLOR00, $0642

    DC.W    $FFFF, $FFFE

    CNOP 0,4
Bitplane1:
    DS.B    40*256