aiie/apple/mouserom.asm

147 lines
3.2 KiB
NASM

.ORG $C400
Entry:
BIT $FF58 ; well-known RTS location - where RTS is $60
BVS PREntry ; always branches (used to relocatably branch)
.ORG $C405
INEntry:
SEC
BCC PREntry ; never happens, but has a magic ID byte @ C407 == 18
CLV
BVC PREntry ; always branches
;; lookup table
.ORG $C40B
.byte $01 ; magic identifier
.byte $20 ; magic identifier
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte $00
.byte .LOBYTE(SetMouse)
.byte .LOBYTE(ServeMouse)
.byte .LOBYTE(ReadMouse)
.byte .LOBYTE(ClearMouse)
.byte .LOBYTE(PosMouse)
.byte .LOBYTE(ClampMouse)
.byte .LOBYTE(HomeMouse)
.byte .LOBYTE(InitMouse)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.byte .LOBYTE(ExitWithError)
.ORG $C420
PREntry:
PHA ; save Y, X, A, S on the stack
TYA
PHA
TXA
PHA
PHP
SEI ; turn off interrupts while we find our address via the stack
JSR $FF58 ; well-known RTS
TSX ; grab stack pointer
LDA $0100,X ; inspect the stack frame
TAX ; now A and X hold the high byte of the return address to *us*
ASL ; A <<= 4
ASL
ASL
ASL
TAY ; so Y = $n0, while X = $Cn for whatever slot we're in
PLP ; pull Status off the stack
BVC lastChance
LDA $38 ; We're being invoked in an IN# context, not a PR# context.
BNE PopAndReturn ; if $38/$39 don't point to us, then exit
TXA
EOR $39 ; is $39 == $Cn?
BNE PopAndReturn
InstallInHandler:
LDA #$05 ; Update IN handler to point to $Cn05 instead of $Cn00, so we know we've
STA $38 ;initialized it
BNE INHandler
lastChance:
BCS INHandler
PopAndReturn:
PLA
TAX
PLA
NOP
PLA
STA $c080,Y ; call soft-switch #0 for our slot to set mouse state
RTS
INHandler:
STA $c081,Y ; call soft-switch #1 for our slot to fill the keyboard buffer w/ mouse info
PLA
LDA $0638,X ; pull the string length from this magic screen hole (X == $Cn)
TAX ; which we'll return to the caller in X
PLA ; restore Y
TAY
PLA ; restore A
LDA $200,X ; Grab the last character entered in to the buffer by the magic switch call
RTS
SetMouse:
CMP #$10 ; values >= $10 are invalid
BCS ExitWithError
STA $C0CF ; soft switch 0x0F, hard-coded slot 4 for now
RTS
ExitWithError:
SEC ; the spec says carry is set on errors
RTS
ServeMouse:
PHA
SEI ; disable interrupts while we find out about interrupts
STA $C0CE ; soft switch 0x0E, hard-coded slot 4 for now
LDX #$04
LDA $6B8,X ; check what interrupts we serviced
AND #$0E
BNE _sm1 ; if we serviced any, leave carry clear
SEC ; ... but set carry if we serviced none
_sm1:
PLA
RTS
ReadMouse:
STA $C0CB ; soft switch 0x0B, hard-coded slot 4 for now
CLC
RTS
ClearMouse:
STA $C0CA ; soft switch 0x0A, hard-coded slot 4 for now
CLC
RTS
PosMouse:
STA $C0C9 ; soft switch 0x09, hard-coded slot 4 for now
CLC
RTS
ClampMouse:
CMP #$02
BCS ExitWithError
STA $C0CD ; soft switch 0x0D, hard-coded slot 4 for now
CLC
RTS
HomeMouse:
STA $C0C8 ; soft switch 0x08, hard-coded slot 4 for now
CLC
RTS
InitMouse:
STA $C0CC ; soft switch 0x0C, hard-coded slot 4 for now
CLC
RTS
.ORG $C4FB
.byte $D6 ; magic identifier
.ORG $C4FF
.byte $01 ; version