81a239325d
Adds Link's Awakening: DX. Fully imports and forks LADXR, with permission - https://github.com/daid/LADXR
90 lines
1.8 KiB
NASM
90 lines
1.8 KiB
NASM
; Handle the serial link cable
|
|
#IF HARDWARE_LINK
|
|
; FF> = Idle
|
|
; D6> = Read: D0><[L] D1><[H] [HL]>
|
|
; D9> = Write: D8><[L] D9><[H] DA><[^DATA] DB><[DATA]
|
|
; DD> = OrW: D8><[L] D9><[H] DA><[^DATA] DB><[DATA] (used to set flags without requiring a slow read,modify,write race condition)
|
|
|
|
handleSerialLink:
|
|
; Check if we got a byte from hardware
|
|
ldh a, [$01]
|
|
|
|
cp $D6
|
|
jr z, serialReadMem
|
|
cp $D9
|
|
jr z, serialWriteMem
|
|
cp $DD
|
|
jr z, serialOrMem
|
|
|
|
finishSerialLink:
|
|
; Do a new idle transfer.
|
|
ld a, $E4
|
|
ldh [$01], a
|
|
ld a, $81
|
|
ldh [$02], a
|
|
ret
|
|
|
|
serialReadMem:
|
|
ld a, $D0
|
|
call serialTransfer
|
|
ld h, a
|
|
ld a, $D1
|
|
call serialTransfer
|
|
ld l, a
|
|
ld a, [hl]
|
|
call serialTransfer
|
|
jr finishSerialLink
|
|
|
|
serialWriteMem:
|
|
ld a, $D8
|
|
call serialTransfer
|
|
ld h, a
|
|
ld a, $D9
|
|
call serialTransfer
|
|
ld l, a
|
|
ld a, $DA
|
|
call serialTransfer
|
|
cpl
|
|
ld c, a
|
|
ld a, $DB
|
|
call serialTransfer
|
|
cp c
|
|
jr nz, finishSerialLink
|
|
ld [hl], a
|
|
jr finishSerialLink
|
|
|
|
serialOrMem:
|
|
ld a, $D8
|
|
call serialTransfer
|
|
ld h, a
|
|
ld a, $D9
|
|
call serialTransfer
|
|
ld l, a
|
|
ld a, $DA
|
|
call serialTransfer
|
|
cpl
|
|
ld c, a
|
|
ld a, $DB
|
|
call serialTransfer
|
|
cp c
|
|
jr nz, finishSerialLink
|
|
ld c, a
|
|
ld a, [hl]
|
|
or c
|
|
ld [hl], a
|
|
jr finishSerialLink
|
|
|
|
; Transfer A to the serial link and wait for it to be done and return the result in A
|
|
serialTransfer:
|
|
ldh [$01], a
|
|
ld a, $81
|
|
ldh [$02], a
|
|
.loop:
|
|
ldh a, [$02]
|
|
and $80
|
|
jr nz, .loop
|
|
ldh a, [$01]
|
|
ret
|
|
|
|
#ENDIF
|