; I implement a "BootServer" on the AppleTalk network
; The Server Desk Accessory installs me in the system heap and opens me

ServerHeader
            dc.w    $4000           ; dNeedLock
            dc.w    0               ; delay
            dc.w    0               ; evt mask
            dc.w    0               ; menu

            dc.w    ServerOpen-ServerHeader
            dc.w    0               ; no Prime
            dc.w    0               ; no Control
            dc.w    0               ; no Status
            dc.w    ServerClose-ServerHeader
            dc.b    14, '.NetBootServer', 0
            dc.b    0, 0, $20, 1    ; version

ServerOpen
            dc.w    $A9FF
            movem.l A0/A1,-(SP)

; Try *once*. AT might come up later but not because of us.
            bsr     TryOpenMPP
            bne.s   .couldNotOpenAppleTalk
            bsr     Listen
.couldNotOpenAppleTalk

; Be ready for the LAP Manager to open/close .MPP
            bsr     RegisterForTransitions

            movem.l (SP)+,A0/A1
            clr.w   $10(A0)         ; return noErr
            rts

ServerClose
            movem.l A0/A1,-(SP)
            bsr     StopListening
            movem.l (SP)+,A0/A1
            clr.w   D0              ; return noErr
            rts

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

TryOpenMPP
; Checking whether the "B" printer port is configured for AppleTalk is an
; application responsibility on 64K ROM machines (as documented in IM),
; but 128K ROM and later machines move this check to AppleTalk itself,
; for example to allow other AppleTalk interfaces.
            tst.w   $28E            ; ROM85 positive?
            bgt.s   .returnYes      ; it is always safe to try on 128K machines

            move.b  $1FB,D0         ; SPConfig & 0xF == useFree (0) or useATalk (1)?
            and.b   #$F,D0
            sub.b   #1,D0
            ble.s   .returnYes

            move.b  $291,D0         ; PortBUse negative or useATalk (1)?
            blt.s   .returnYes
            cmp.b   #1,D0
            beq.s   .returnYes

.returnNo   moveq   #1,D0
            rts

.returnYes
            sub     #$32,SP
            lea     .MPP,A0
            move.l  A0,$12(SP)      ; IOFileName
            clr.b   $1B(SP)         ; IOPermssn
            move.l  SP,A0
            dc.w    $A000           ; _Open
            tst.w   $10(A0)         ; IOResult: check it
            add     #$32,SP
            rts

.MPP        dc.b    4, '.MPP', 0

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

RegisterForTransitions rts ; register for the LAP Manager queue if possible

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

Listen
            sub     #$32,SP         ; OPEN DDP SOCKET
            move.w  #-10,$18(SP)        ; ioRefNum = MPP
            move.w  #248,$1A(SP)        ; csCode = openSkt
            clr.b   $1C(SP)             ; socket = auto-assign
            pea     SocketListener
            move.l  (SP)+,$1E(SP)       ; listener
            move.l  SP,A0
            dc.w    $A004               ; _Control
            lea     NameTableEntry+7,A0 ; lowest byte of AddrBlock
            move.b  $1C(SP),(A0)        ; save socket number there
            add     #$32,SP

            sub     #$32,SP         ; ADVERTISE NBP SERVICE
            move.w  #-10,$18(SP)        ; ioRefNum = MPP
            move.w  #253,$1A(SP)        ; csCode = registerName
            move.b  #7,$1C(SP)          ; interval = 7*8 ticks = 1sec
            move.b  #5,$1D(SP)          ; count = 5
            pea     NameTableEntry
            move.l  (SP)+,$1E(SP)       ; entityPtr = our NTE
            move.b  #1,$22(SP)          ; verifyFlag = do
            move.l  SP,A0
            dc.w    $A004               ; _Control
            add     #$32,SP

            rts

NameTableEntry
            dc.l    0                   ; qLink
            dc.l    0                   ; addrblock
            dc.b    0                   ; odd address
            dc.b    4, '0000'           ; object
            dc.b    10, 'BootServer'    ; type
            dc.b    1, '*'              ; zone
            even

StopListening
            sub     #$32,SP         ; REMOVE NBP SERVICE
            move.w  #-10,$18(SP)        ; ioRefNum = MPP
            move.w  #252,$1A(SP)        ; csCode = removeName
            pea     NameTableEntry
            move.l  (SP)+,$1E(SP)       ; entityPtr = our NTE
            move.l  SP,A0
            dc.w    $A004               ; _Control
            add     #$32,SP

            sub     #$32,SP         ; CLOSE DDP SOCKET
            move.w  #-10,$18(SP)        ; ioRefNum = MPP
            move.w  257,$1A(SP)         ; csCode = closeSkt
            move.b  NameTableEntry+7,$1C(SP); socket = auto-assign
            move.l  SP,A0
            dc.w    $A004               ; _Control
            add     #$32,SP

            rts

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SocketListener ; DDP socket listener, very tricky piece of code!
            dc.w    $A9FF