þa‹RþwQþ m^9þhý oPþ nSystem-wide NAME Roms ; This is Rom.Asm. This file contains ; the routines that deal with the low level ; roms DGROUP GROUP DATA CGROUP GROUP CODE PUBLIC CpGetMySlot, CpBankInfo, CpSetActiveSlot, CpGetSlotAddress PUBLIC curSlot, slotInfo, numSlots ; constants TRUE EQU 1 FALSE EQU 0 nullWord EQU 0ffffh nullByte EQU 0ffh numRomSlots EQU 4 thirtyTwoKOff EQU 0A2h thirtyTwoKMask EQU 80h setThirtyTwo EQU 1 clearThirtyTwo EQU 0 SlotInfoType STRUC waitStateCode DB ? romID DW ? slotAddress DW ? validRom DB ? slots DB ? spare DB ? SlotInfoType ENDS slotInfoTypeSize EQU 8 ; this size must be a power of 2, and 8 is assumed ; in many ways slotOffsetFromSP EQU 4 ; where value slot will be if only argument addr1Sel EQU 0dfe0h addr1Off EQU 08h $EJ ; data DATA SEGMENT PUBLIC 'DATA' curSlot DB ? numSlots DB ? slotInfo SlotInfoType numRomSlots DUP (<>) temp DB ? DATA ENDS $EJ CODE SEGMENT PUBLIC 'CODE' ASSUME CS:CGROUP ; CpBankInfo : PROCEDURE PTR CLEAN ; ; This will return a pointer to the slot information CpBankInfo PROC FAR MOV AX, DATA MOV ES, AX MOV BX, OFFSET curSlot RET CpBankInfo ENDP $EJ ; CpGetSlotAddress : PROCEDURE (slot) PTR CLEAN ; DCL slot BYTE; ; ; This will return the actual address of a given slot ; by looking at the table that was set up init time ; If slot is nullByte, then curSlot will be used CpGetSlotAddress PROC FAR MOV AX, DATA MOV ES, AX MOV SI, SP ADD SI, slotOffsetFromSP MOV BL, SS:[SI] ; BL := slot CMP BL, nullByte ; IF slot = nullByte THEN JNE CpGetCont MOV BL, ES:curSlot ; slot := curSlot CpGetCont: XOR BH, BH ; BH := 0 SHL BX, 1 SHL BX, 1 ; BX := slot * 8 SHL BX, 1 ADD BX, OFFSET slotInfo ; now ES:BX ^ element of slotInfo MOV AX, ES:[BX].slotAddress ; AX := selector of address MOV ES, AX ; return in ES:BX XOR BX, BX ; BX := 0 RET 2 CpGetSlotAddress ENDP $EJ ; CpGetMySlot : PROCEDURE (romID) BYTE CLEAN ; DCL romID WORD ; ; This will return the slot # of the rom which ; has the given ID. If the romID is not found, then ; nullByte will be returned CpGetMySlot PROC FAR MOV AX, DATA MOV ES, AX MOV BX, OFFSET slotInfo ; ES:BX ^ first element of slotInfo MOV SI, SP ADD SI, slotOffsetFromSP MOV DX, SS:[SI] ; DX = romID MOV CX, numRomSlots XOR AL, AL ; AX (slot) = 0 CpGetMyTopOfLoop: CMP ES:[BX].romID, DX ; IF romID = slotInfo(i).romID THEN JE CpGetMyDone ; RETURN (AL) ADD BX, slotInfoTypeSize ; ES:BX ^ next element INC AL ; slot = slot + 1 LOOP CpGetMyTopOfLoop MOV AL, nullByte ; romID was not found RETURN (nullByte) CpGetMyDone: RET 2 CpGetMySlot ENDP $EJ ; CpSetActiveSlot : PROCEDURE (slot) BYTE CLEAN; ; DCL slot BYTE; ; ; This will make the rom is slot be the "active" rom. ; It assumes that slot is either valid, or nullByte. The ; current active slot will be returned. CpSetActiveSlot PROC FAR MOV AX, DATA MOV ES, AX MOV DL, ES:curSlot ; save current slot MOV SI, SP ADD SI, slotOffsetFromSP MOV AL, SS:[SI] ; AL = slot CMP AL, NULLBYTE ; IF AL = nullByte THEN RETURN JE CpSetDone MOV BL, AL XOR BH, BH SHL BL, 1 SHL BL, 1 SHL BL, 1 ADD BX, OFFSET slotInfo ; Before going further check if this is a valid slot CMP ES:[BX].validRom, 1 ; IF NOT slot.validRom THEN RETURN JE SetTheSlot MOV DL, NULLBYTE ; oldSlot = NULLBYTE JMP CpSetDone SetTheSlot: MOV ES:curSlot, AL ; curSlot := slot ; ES:BX ^ proper entry in slotInfo MOV DH, ES:[BX].slots ; all the slots to set MOV AH, ES:[BX].waitStateCode ; num wait states for all slots MOV BX, addr1Sel ; point to rom select area MOV ES, BX ; See if we have a 32k rom MOV BX, thirtyTwoKOff ; set 32k mode MOV AL, setThirtyTwo ; 256Kbit part TEST AH, thirtyTwoKMask JNZ NowWriteIt MOV AL, clearThirtyTwo ; 1 Mbit part NowWriteIt: MOV ES:[BX], AL ; set or clear the 32k flag MOV BX, addr1Off ; first 32k area MOV CX, 4 ; 4 roms to set BackToHere: MOV AL, DH AND AL, 3 ; mask all but this slot OR AL, AH ; add in the wait states MOV ES:[BX], AL ; write out the code INC BX INC BX SHR DH, 1 SHR DH, 1 Loop BackToHere CpSetDone: MOV AL, DL ; return current slot RET 2 CpSetActiveSlot ENDP CODE ENDS END