Developer CD Series 1997 April: Mac OS SDK

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Text File | 1993-02-15 | 22.6 KB | 718 lines | [TEXT/MPS ]

;_________________________________________________________________________________ ; ; File: XTIShell.a ; ; This file contains code that implements calls from AURP to the adev. Once ; the call is determined, a routine in C is usually called to perform the guts ; of the call (with a few exceptions). These C routines can be found in XTIShell.c. ; Hints on things that may need to be change are provided throughtout. ; ; Apple Computer, Inc. ; Copyright (C) 1992,1993. All rights reserved. ; ; Revision History: ; ;__________________________________________________________________________________ PRINT PUSH,OFF INCLUDE 'SysEqu.a' ; System definitions INCLUDE 'SysErr.a' ; System errors INCLUDE 'ToolEqu.a' ; Toolbox definitions INCLUDE 'Traps.a' ; Traps definitions INCLUDE 'LAPEqu.a' ; LAP manager defs INCLUDE 'AURPEqu.a' ; AURP atlk definitions INCLUDE 'HardwareEqu.a' ; some hardware stuff INCLUDE 'Private.a' ; System private definitions PRINT POP EXPORT GETSYSMEM, GETMYA5, SETMYA5 ; ; The main shell structure. Modify if necessary, but the variables ; provided should be sufficient. ; XTIvarsRec RECORD 0 ; MIRROR XTISHELL.H cGlobals DS.L 1 ; Ptr to variables used in C routine HopCntWght DS.W 1 ; ipt's hop count weight remoteAddr DS.B 16 ; remote DTE address as pascal string AURPWriteEntry DS.L 1 ; AURP LAP write code entry point AURPRefNum DS.L 1 ; AURP refnum NextIRBlk DS.L 1 ; next IR lineSpeed DS.L 1 ; faked line speed to tell the router AURPDispatch DS.L 1 ; aurp dispatch routine OurDI DS.W 1 ; our domain identifier otherNode DS.L 1 ; domain identifier maxRPktSz DS.W 1 ; maximum packet size wDSPtr DS.L 1 ; WDSPtr for XTIWRITE rcvBufAvail DS.B 1 ; set flag if receive buffer is available rcvPktsWaiting DS.B 1 ; flag will be set in C routine if data are outstanding XTIFlags DS.B 1 ; flags for this atlk OurPortId DS.B 1 ; Our port id OurSlotId DS.B 1 ; Our slot id , will be set in C routine XTIvarsize DS.B 0 ENDR LWEnableSCC EQU 6 ; Don't disable SCC ; XTIFlags bits XTIInit EQU 0 ; bit 0, set if init'ed XTIClose EQU 1 ; bit 1, set if closing XTILapInst EQU 2 ; bit 2, set if LAP write code is installed ;________________________________________________ ; ; Begin main atlk code ; ;________________________________________________ XTISHELL MAIN EXPORT ; this entry point is the LAPWRITE hook IMPORT DOXTIINSTALL, DOXTIDISCONNECT, DOXTISHUTDOWN, XTICONNECT, XTIWRITE, READDONE EXPORT CONNDONE, GETGLOBALS WITH XTIVarsRec ; ; If the code is entered at this point, the LAP Manager is calling the adev ; to perform a write, so just branch to the LAPWrite code. ; BRA.S LAPWrite ; ; AURP is calling us. On entry D0 contains command code. Use the jump tables ; (ControlTable and XTICntrlTbl) to jump to appropriate routine. ControlTable ; has a base of D0 = 0, and XTICntrlTbl has a base of D0 = 32. This code should ; NOT need any modifications. ; XTIControl LINK A6,#0 ; allocate our local stack frame MOVEM.L A2-A3/D3-D4,-(SP) ; save these registers ; for all control calls. CMP.W #AInstall,D0 ; is it an install call? BNE.S @tryAGetIF ; branch if not @ProcReq MOVE.L D1,-(SP) ; save this reg. ADD.W D0,D0 ; D0 = D0 * 2; MOVE.W ControlTable(D0.W),D0 ; get the routine offset JSR ControlTable(D0.W) ; process the request BRA.S @XTICntrlDone @tryAGetIF MOVE.L ATLKVars,A3 ; A3 -> our variables CMP.W #AGetInfo,D0 ; is it a get info call? BEQ.S @ProcReq ; branch if so @tryShutDwn CMP.W #AShutdown,D0 ; is it a shutdown call? BEQ.S @ProcReq ; branch if so CMP.W #ATnlGetNextIR,D0 ; is it a NextIR req call? BEQ.S @ProcReq2 ; branch if so CMP.W #ATnlDisconnect,D0 ; is it a disconnect req call? BEQ.S @ProcReq2 ; branch if so CMP.W #ATnlConnect,D0 ; is it a connect call? BNE.S @ParamError ; branch if not @ProcReq2 MOVE.L D1,-(SP) ; save this reg. SUB.W #ATnlConnect,D0 ; adjust call # for 2nd tbl ADD.W D0,D0 ; D0 = D0 * 2; MOVE.W XTICntrlTbl(D0.W),D0 ; get the routine offset JSR XTICntrlTbl(D0.W) ; process the request @XTICntrlDone MOVE.L (SP)+,D1 ; restore this one MOVEM.L (SP)+,A2-A3/D3-D4 UNLK A6 RTS @ParamError MOVEM.L (SP)+,A2-A3/D3-D4 BSR.S ParamError UNLK A6 RTS ; ; The LAP Manager wants us to write out a packet. ; Give it to AURP. ; LAPWrite: CMP.B #0,D0 ; Write pkt out? MOVE.L ATLKvars, A3 MOVE.L XTIVarsRec.AURPRefNum(A3), D1 MOVE.L XTIVarsRec.AURPWriteEntry(A3), A3 JMP (A3) ; ; The control table for standard atlk calls made from AURP ; ControlTable DC.W ParamError-ControlTable ; D0 = 0 not supported DC.W DoInstall-ControlTable ; D0 = 1 AInstall Lap DC.W DoShutdownAtlk-ControlTable ; D0 = 2 AShutdown Lap DC.W DoGetInfo-ControlTable ; D0 = 3 AGetInfo ; ; The control table for AURP specific atlk calls made from AURP ; Note: D0 base is 32. ; XTICntrlTbl DC.W DoATlkConnect-XTICntrlTbl ; D0 = 0 ATnlConnect DC.W DoATnlDisconnect-XTICntrlTbl ; D0 = 1 ATnlDisconnect pkt DC.W GetNextIR-XTICntrlTbl ; D0 = 2 return next ir ParamError MOVEQ.L #-1,D0 ; Indicate failure RTS ; ; XTIShellVarsPtr GETGLOBALS (void) ; GetGlobals MOVE.L ATLKvars,D0 RTS ATLKvars DC.L 0 ; a pointer to our vars UNLK A6 RTS ;________________________________________________ ; ; DoInstall ; ; This code performs the installation of the adev (AURP AInstall). ; Possible modifications to be made are the Domain Indicator and ; NextIRBlock returned to AURP, but should not be necessary except ; for point to point links. ; ; Call: ; D3.L = AURP LAP write code entry point ; D4.L = port number on which to perform the install operation ; A0.L -> AURP Interface Dispatch Routine ; A1 -> pointer to ATnlConfig parameter block ; A2 = AURP Refnum ; ; Return: ; D0.W = error code (non zero indicates an error) ; A1 -> pointer to ATnlConfig parameter block ; ;________________________________________________ InstallErr MOVEM.L (SP)+,A0-A1 ; clean up stack BRA CloseADEV ; and close Install2Err MOVE.L ATLKvars, A0 _DisposPtr ; dispose of the ATLKvars MOVEM.L (SP)+, A0-A1 ; clean up stack BRA CloseADEV ; and close Install3Err MOVE.L ATLKvars, A0 _DisposPtr ; dispose of the ATLKvars MOVE.L NextIRBlk(A3), A0 _DisposPtr ; dispose of the NextIRBlk MOVEM.L (SP)+, A0-A1 ; clean up stack BRA CloseADEV ; and close DoInstall ; initialization MOVEM.L A0-A1,-(SP) ; save off rtmi ptr and port info pb MOVE.L #XTIvarsize,D0 ; size of our vars _NewPtr ,SYS,CLEAR ; get some memory BNE.S InstallErr ; no can do LEA ATLKvars,A3 MOVE.L A0,(A3) ; save vars ptr MOVE.L A0,A3 ; A3-> our vars MOVE.L D3, AURPWriteEntry(A3) ; save the write entry code pointer MOVE.L A2, AURPRefNum(A3) ; save the AURP vars MOVE.L #6, D0 _NewPtr ,SYS,CLEAR ; get some memory BNE.S Install2Err MOVE.L A0, XTIVarsRec.NextIRBlk(A3) ; save the next IR blk value MOVE.B D4,OurPortId(A3) ; save our port number MOVEM.L (SP),A0-A1 ; restore A0 & A1 = port info pb MOVE.L A1, A2 ; move the port info pointer into A2 MOVE.L A0,AURPDispatch(A3) ; save aurp dispatch routine MOVE.W ATnlCfgPBlk.HopCntWgt(A2),D0 ; save hopcount weight MOVE.W D0, HopCntWght(A3) MOVE.L ATnlCfgPBlk.PaidPtr(A2),A0 ; A0 -> paid ptr (src ptr) ADDQ.L #2, A0 ; skip length MOVE.L A0, -(SP) ; move paid ptr onto stack MOVE.L ATnlCfgPBlk.ACfgPtr(A2),A0 ; A0 -> acfg ptr (src ptr) MOVE.L A0, -(SP) ; move acfg ptr onto stack MOVE.L A3, -(SP) ; move varsPtr onto stack JSR DOXTIINSTALL ; call C routine ADDA #12, SP TST.W D0 BNE.S Install3Err ; no can do MOVEM.L (SP)+,A0-A1 ; restore A0 & A1 = port info pb MOVE.L A1, A2 ; move the port info pointer into A2 ; ; Insert atlk's LAP write code ; @InsertLW MOVEA.L LAPMgrPtr,A1 ; A1->LAPmgr MOVEQ #LWrtInsert,D0 ; func code LEA XTISHELL,A0 ; A0->us CLR.B D1 CLR.W D2 ; try ENQ's forever maybe BSET #LWEnableSCC,D1 ; don't disable SCC when calling us JSR LAPMgrCall(A1) ; install ourself as new LAPWrite BSET #XTILapInst, XTIFlags(A3) ; set flag that LAP write code is installed ; ; Setup the ATnlPBlk entries to give to AURP ; A2 still equals the pointer to ATnlConfigPB ; MOVE.L #0, D2 MOVE.W maxRPktSz(A3), D2 ; D2 = max packet size MOVE.W D2, ATnlCfgPBlk.maxRPktSz(A2) ; D2 needs to be size of Packet MOVEQ #0, D1 ; D1 = kRtr flags BSET.L #ConfigLstOnly, D1 ; use only our list of one MOVE.L D1, ATnlCfgPBlk.atlkFlags(A2) ; set up the router host flags LEA DoXTIWrite, A0 MOVE.L A0, ATnlCfgPBlk.atlkWriteCode(A2) ; setup the write code LEA FreeReadBuf, A0 MOVE.L A0, ATnlCfgPBlk.atlkReadDone(A2) ; setup the read done code MOVE.W #1, ATnlCfgPBlk.numNextIRs(A2) ; setup num next IRs MOVE.B #1, ATnlCfgPBlk.srcDILen(A2) ; set up our srcDI length ; ; The domain indicator for a point to point link is set to 1. This indicator ; is more relevant for multipoint links for routers to distinguish who the ; information is coming from. On point to point links, there is only one other ; router the data could be coming from. ; LEA XTIVarsRec.OurDI(A3), A1 ; save ourDI MOVE.W #$0100, (A1) ; this is the null DI ; ; The otherNode variable is set in XTIShell.c to a value indicating that ; the other (next) router (in this case the other end of the point to point ; link) is answering or calling. This information is used in a multipoint link ; when AURP indicates a write is to be made to know which router to write to. ; However, with a point to point link, there is only one router to write to, ; making nextIR irrelevant. ; MOVE.L XTIVarsRec.NextIRBlk(A3),A0 ; get the next IR blk value MOVE.W #1, (A0) ; save length = 1 MOVE.L otherNode(A3), 2(A0) ; save other nir MOVE.L A0, -(SP) ; next ir block ptr PEA XTIVarsRec.OurDI(A3) ; our address MOVE.L XTIVarsRec.AURPRefNum(A3), -(SP) ; the aurp vars MOVE.L #kAURPInstallDone, -(SP) ; csCode = AURPInstallDone MOVE.L XTIVarsRec.AURPDispatch(A3), A0 ; the dispatch rtn JSR (A0) ; call it ADDA #16, SP ; CLR.W D0 ; set return code for caller RTS ;________________________________________________ ; ; DoGetInfo ; ; This code performs the AURP AGetInfo call to get information ; about the adev. Possible modification would be to the link ; address (probably not). Since most of the variables are set ; in the C routines, this code is probably ok. ; ; Call: ; D1.W = length of reply buffer ; A1.L -> reply buffer ; ; ; Return: A1.L -> reply buffer ; D0.W = Result code ;________________________________________________ WITH ATlkInfo DoGetInfo: CMP.W #AInfoSz,D1 ; buffer big enough? BLT.S @Error ; no MOVE.L ATLKvars,D3 ; has this atlk been installed? BEQ.S @Error ; no MOVE.L D3,A3 ; A3 -> our vars MOVE.L A1,A2 ; MOVE.W #AInfoVers,Version(A2) ; version (of atlk) MOVE.W #AInfoSz,InfoLength(A2) ; number of bytes returned BTST.B #XTIInit, XTIFlags(A3) ; see if we've inited BNE.S @initInfo ; if so, give real values MOVE.L lineSpeed(A3),LinkSpeed(A2) ; the line speed CLR.B BandWidth(A2) ; bandwidth (weight factor) BRA.S @contInfo @initInfo MOVE.B HopCntWght+1(A3),Bandwidth(A2) ; link weight (value returned from AURP + 1) @contInfo CLR.B Reserved(A2) ; reserved (must be zero) CLR.W Reserved+1(A2) MOVE.B OurSlotId(A3), Reserved+1(A2) ; "slot number" in second reserved byte for SNMP MOVEQ #0,D0 ; flags BSET #AtlkExtended,D0 ; extended port MOVE.B D0,Flags(A2) MOVE.B #0,LinkAdrLen(A2) ; no relevant addr MOVEQ #noErr,D0 RTS ; return success @Error MOVEQ #-1,D0 ; return error RTS ;________________________________________________ ; ; DoAtlkConnect ; ; This code performs the AURP ATnlConnect call. The guts of the call ; are performed in the C routine XTICONNECT. Should NOT need to be ; modified. ; ; No parameters sent in. ; ; Return: D0.W = Result code ;________________________________________________ DoAtlkConnect MOVE.L ATLKvars, A3 BCLR #XTIClose, XTIFlags(A3) ; connection no longer closed MOVE.L A3, -(SP) ; pass our vars JSR XTICONNECT ; call C routine to start connection ADDQ.L #4,SP ; restore stack TST.W D0 BNE CloseADEV RTS ;__________________________________________ ; ; ConnDone (long errResult); ; ; This routine is called from several C routines to indicate that ; a connection is complete, a connection could not be established, ; or a connection has gone down unexpectedly. AURPTnlConnDone is ; called with noErr or with an error (latter two cases). If it is ; called with an error, the port will be made inactive. Should ; NOT need to be modified. ; ;__________________________________________ CONNDONE MOVE.L A3, -(SP) ; save A3 MOVE.L ATLKvars, A3 ; get our vars MOVE.L 8(A7), D0 ; see if connection good BNE.S @ConnErr ; if not, error BSET #XTIInit, XTIFlags(A3) ; set flag that init done MOVE.L #0, -(SP) ; the connection result MOVE.L AURPRefNum(A3), -(SP) ; pass the vars MOVE.L #kAURPTnlConnDone, -(SP) ; cmdType = TnlConnection Done MOVE.L AURPDispatch(A3), A3 ; JSR (A3) ; make the call ADDA #12, SP MOVE.L (SP)+, A3 RTS @ConnErr MOVE.L ATLKvars, A3 BTST #XTIClose, XTIFlags(A3) ; see if closing BNE.S @ConnEx MOVE.W #-1, D0 MOVE.L D0, -(SP) ; the connection result MOVE.L AURPRefNum(A3), -(SP) ; pass the vars MOVE.L #kAURPTnlConnDone, -(SP) ; cmdType = TnlConnection Done MOVE.L AURPDispatch(A3), A3 ; JSR (A3) ; make the call ADDA #12, SP @ConnEx MOVE.L (SP)+, A3 ; restore A3 RTS ;__________________________________________ ; ; GetNextIR ; ; Performs the AURP ATnlGetNextIR call. Returns the ; address of the other router. The next IR reference ; indicator is not looked at because this is a point ; to point implementation and there is only one ; next IR. If you have used the remoteAddr field, this ; code should NOT need to be modified. May want to tailor ; the string based on whether the router is active or ; passive on connect. For example, DialUp, returns "Answering" ; if the router is in answer mode. ; ; Call: D1 = next ir ref indicator ; A1 -> next ir string ptr (up to 16 bytes) ; ; ; Return: A1 -> next IR String ; D0.L = error code ; ;__________________________________________ NIRStrMax EQU 32 GetNextIR MOVEQ #0, D0 ; clear out D0 MOVE.L #-1,D3 ; assume error MOVE.L ATLKvars, A3 ; get the globals pointer BTST.B #XTIInit, XTIFlags(A3) ; make sure init'd BEQ.S @GetNxtIRErr ; error if not CMP.B #NIRStrMax-1, remoteAddr(A3) ; see if less than max BLS.S @getStrLen MOVE.B #NIRStrMax-1, D0 ; if greater than max, length byte is max - 1 BRA.S @copyStr @getStrLen MOVE.B remoteAddr(A3), D0 ; actual length @copyStr MOVE.B D0, (A1)+ ; length byte LEA remoteAddr+1(A3), A0 ; A0 = ptr to remote addr (src) _BlockMove MOVEQ #0,D3 ; set result code to no err @GetNxtIRErr MOVE.L D3,D0 ; move result to D0 RTS ;__________________________________________ ; ; DoATnlDisconnect ; ; Performs the AURP ATnlDisconnect call. Main code is in C routine ; DoXTIDisconnect. This code should NOT need to be modified. ; ; Call: A3.L -> our vars ; ; Return: D0.L = error code ; ;__________________________________________ DoATnlDisconnect MOVE.L ATLKvars, A3 ; get the globals pointer BSET #XTIClose, XTIFlags(A3) ; set flag for closing... MOVE.L A3, -(SP) JSR DOXTIDISCONNECT ; Call C routine ADDQ.L #4, SP BCLR #XTIInit, XTIFlags(A3) ; no longer inited... MOVE.L D0, -(SP) ; the disconnect result MOVE.L AURPRefNum(A3), -(SP) ; the refnum CLR.L D0 MOVE.B #kAURPTnlDiscDone, D0 ; csCode = AURPTnlDiscDone MOVE.L D0, -(SP) MOVE.L AURPDispatch(A3), A0 JSR (A0) ; make the call ADDA #12, SP CLR.L D0 ; the disconnect result RTS ;_____________________________________________ ; ; DoShutdownAtlk ; ; Performs the AURP AShutdown call. ; ; Call: D4.B = port number on which to perform the shutdown ; ; Return: D0 = error code ; ;_____________________________________________ DoShutdownAtlk MOVEQ #0,D0 ; no init error has occurred ; shut down normally ;_____________________________________________ ; ; CloseADEV ; ; Complete shutdown. Also called when an error occurs during ; installation or when connecting. This code should NOT need ; to be modified. ; ; Return: D0.L = error code ; ;_____________________________________________ CloseADEV MOVE.L D0,D3 ; save error code MOVE.L ATLKvars,D0 ; do we have our vars? BEQ.S DoneClose MOVE.L D0,A3 ; A3 -> our vars BTST #XTIInit, XTIFlags(A3) ; see if we've been inited BEQ.S @SkipClose ; if not, skip close of endpoint JSR DoATnlDisconnect BRA.S @ContClose ; br to dispose memory @SkipClose BSET #XTIClose, XTIFlags(A3) ; set flag for closing... @ContClose BSR.S DeAllocMem MOVE.W D3,D0 ; pass the error code RTS DeAllocMem MOVE.L A3, -(SP) JSR DOXTISHUTDOWN ; call C routine to dispose memory ADDQ.L #4, SP BTST.B #XTILapInst, XTIFlags(A3) ; see if LAP write code is installed BEQ.S @NoLAPMgr MOVEM.L D4,-(SP) ; save D4 MOVE.B OurPortId(A3),D4 ; D4 = our port id MOVE.L LAPMgrPtr,A1 ; A1 -> LAP manager MOVEQ #LWrtRemove,D0 ; function code JSR LAPMgrCall(A1) ; call the LAP manager to remove us MOVEM.L (SP)+,D4 ; restore D4 @NoLAPMgr MOVE.L A3,A0 ; A0 -> our variables _DisposPtr ; get rid of them MOVE.L NextIRBlk(A3), A0 _DisposPtr ; dispose of the NextIRBlk LEA ATLKvars,A0 CLR.L (A0) ; clear vars ptr DoneClose RTS ; That's it (CDEV will dispose us) ; ___________________________________________ ; ; FreeReadBuf ; ; Routine called after route receive completes (ATnlReadDone). ; Set the flag indicating the receive buffer is free, then ; check to see if there are packets waiting to be read. If ; there are, go read them. This code should NOT need to be ; modified unless the read packet scheme is modified. ; ; ___________________________________________ FreeReadBuf IMPORT RESTORESR JSR RESTORESR ; restore interrupt level MOVE.L ATLKvars, A0 ; A0 -> our vars; MOVE.B #1, rcvBufAvail(A0) ; set rcvBufAvail boolean MOVEQ #0,D0 MOVE.B rcvPktsWaiting(A0), D0 TST.W D0 ; if there are no packets waiting to be read BEQ.S @FreeDone ; we are done MOVE.L A0, -(SP) ; pass our vars JSR READDONE ; call C routine to read packets ADDQ.L #4,SP ; restore stack @FreeDone RTS ; ___________________________________________ ; ; DoXTIWrite (NIRIndicator dstNextIR, WDSElement *wdsPtr) ; ; Performs the AURP ATnlDoWrite call. Send the ; packet out on the wire. If an error occurs, call AURPWriteDone ; with an error. Otherwise, it will be called when the T_SendComplete ; event is received. This code should NOT need to be modified. ; ; Call: ; ; ___________________________________________ DoXTIWrite MOVE.L ATLKvars, A3 MOVE.L 8(SP), wDSPtr(A3) ; wDSPtr -> send buffer MOVE.L A3, -(SP) ; pass our vars JSR XTIWRITE ; call C routine to start connection ADDQ.L #4,SP ; restore stack TST.W D0 BNE.S @WriteErr RTS @WriteErr MOVE.L D0,-(SP) ; the writeResult CLR.L D0 MOVE.L ATLKvars,A1 MOVE.L wDSPtr(A1), -(SP) ; the wdsptr MOVE.L XTIVarsRec.AURPRefNum(A1),-(SP) ; AURP vars MOVE.L #kAURPWriteDone, -(SP) ; the cmd type MOVE.L XTIVarsRec.AURPDispatch(A1), A0 JSR (A0) ; call write done with an error ADDA #16, SP RTS ;________________________________________________ ; ; GETSYSMEM (long sizeNeeded); ; ; Allocates specified amount of memory in the system heap. ; This code should NOT need to be modified. ; ;________________________________________________ GETSYSMEM PROC MOVE.L 4(A7), D0 ; get amount to alloc _NewPtr ,SYS,CLEAR ; call memory mgr BNE.S @5 ; error MOVE.L A0, D0 ; otherwise, get pointer BRA.S @10 @5 CLR.L D0 ; if err, D0=0 @10 RTS ; return with pointer in D0 ENDPROC ;________________________________________________ ; ; GETMYA5, SETMYA5 ; ; Get and set A5. Needed to get global variable AtlkVars ; from a routine called by the time manager. This code should ; NOT need to be modified. ; ;________________________________________________ GETMYA5 PROC MOVE.L A5,D0 RTS ENDPROC SETMYA5 PROC MOVE.L 4(A7), A5 RTS ENDPROC ;________________________________________________ ; ; GETSR, RESTORESR ; ; Set and Restore the interrupt level. Needed because ; the router sets the interrupt level to VSCCEnable ; on completion of a read call. ; ;________________________________________________ GETSR PROC EXPORT EXPORT RESTORESR LEA SRX,A0 ; A0 -> SRX global MOVEQ #0,D0 ; clear D0 MOVE SR,D0 ; put the status register into D0 MOVE.L D0,(A0) ; save the status register RTS SRX DS.L 1 RESTORESR MOVE.L SRX,D0 ; saved value into D0 MOVEQ #0,D1 MOVE SR,D1 ; current status register in D1 ANDI #$0700,D1 ; and with 0x07 to get interrupt level ANDI #$0700,D0 ; same with D0 CMP.L D0,D1 ; if they aren't the same, BGE.S @restore ; go to restore the status RTS @restore MOVE.L SRX,D0 ; saved value in D0 MOVE D0,SR ; saved value in status register RTS ENDPROC END