Microsoft Programmer's Library 1.3

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Assembly Source File | 1988-08-11 | 28.1 KB | 901 lines

Title COMDVR Driver for IBM COM Ports ; Jim Kyle, 1987 ; Based on ideas from many sources...... ; including Mike Higgins, CLM March 1985; ; public-domain INTBIOS program from BBS's; ; COMBIOS.COM from CIS Programmers' SIG; and ; ADVANCED MS-DOS by Ray Duncan. Subttl MS-DOS Driver Definitions Comment * This comments out the Dbg macro..... Dbg Macro Ltr1,Ltr2,Ltr3 ; used only to debug driver... Local Xxx Push Es ; save all regs used Push Di Push Ax Les Di,Cs:Dbgptr ; get pointer to CRT Mov Ax,Es:[di] Mov Al,Ltr1 ; move in letters Stosw Mov Al,Ltr2 Stosw Mov Al,Ltr3 Stosw Cmp Di,1600 ; top 10 lines only Jb Xxx Xor Di,Di Xxx: Mov Word Ptr Cs:Dbgptr,Di Pop Ax Pop Di Pop Es Endm * ; asterisk ends commented-out region ; ; Device Type Codes DevChr Equ 8000h ; this is a character device DevBlk Equ 0000h ; this is a block (disk) device DevIoc Equ 4000h ; this device accepts IOCTL requests DevNon Equ 2000h ; non-IBM disk driver (block only) DevOTB Equ 2000h ; MS-DOS 3.x out until busy supported (char) DevOCR Equ 0800h ; MS-DOS 3.x open/close/rm supported DevX32 Equ 0040h ; MS-DOS 3.2 functions supported DevSpc Equ 0010h ; accepts special interrupt 29H DevClk Equ 0008h ; this is the CLOCK device DevNul Equ 0004h ; this is the NUL device DevSto Equ 0002h ; this is standard output DevSti Equ 0001h ; this is standard input ; ; Error Status BITS StsErr Equ 8000h ; general error StsBsy Equ 0200h ; device busy StsDne Equ 0100h ; request completed ; ; Error Reason values for lower-order bits ErrWp Equ 0 ; write protect error ErrUu Equ 1 ; unknown unit ErrDnr Equ 2 ; drive not ready ErrUc Equ 3 ; unknown command ErrCrc Equ 4 ; cyclical redundancy check error ErrBsl Equ 5 ; bad drive request structure length ErrSl Equ 6 ; seek error ErrUm Equ 7 ; unknown media ErrSnf Equ 8 ; sector not found ErrPop Equ 9 ; printer out of paper ErrWf Equ 10 ; write fault ErrRf Equ 11 ; read fault ErrGf Equ 12 ; general failure ; ; Structure of an I/O request packet header. ; Pack Struc Len Db ? ; length of record Prtno Db ? ; unit code Code Db ? ; command code Stat Dw ? ; return status Dosq Dd ? ; (unused MS-DOS queue link pointer) Devq Dd ? ; (unused driver queue link pointer) Media Db ? ; media code on read/write Xfer Dw ? ; xfer address offset Xseg Dw ? ; xfer address segment Count Dw ? ; transfer byte count Sector Dw ? ; starting sector value (block only) Pack Ends Subttl IBM-PC Hardware Driver Definitions page ; ; 8259 data PIC_b Equ 020h ; port for EOI PIC_e Equ 021h ; port for Int enabling EOI Equ 020h ; EOI control word ; ; 8250 port offsets RxBuf Equ 0F8h ; base address Baud1 Equ RxBuf+1 ; baud divisor high byte IntEn Equ RxBuf+1 ; interrupt enable register IntId Equ RxBuf+2 ; interrupt identification register Lctrl Equ RxBuf+3 ; line control register Mctrl Equ RxBuf+4 ; modem control register Lstat Equ RxBuf+5 ; line status register Mstat Equ RxBuf+6 ; modem status register ; ; 8250 LCR constants Dlab Equ 10000000b ; divisor latch access bit SetBrk Equ 01000000b ; send break control bit StkPar Equ 00100000b ; stick parity control bit EvnPar Equ 00010000b ; even parity bit GenPar Equ 00001000b ; generate parity bit Xstop Equ 00000100b ; extra stop bit Wd8 Equ 00000011b ; word length = 8 Wd7 Equ 00000010b ; word length = 7 Wd6 Equ 00000001b ; word length = 6 ; ; 8250 LSR constants xsre Equ 01000000b ; xmt SR empty xhre Equ 00100000b ; xmt HR empty BrkRcv Equ 00010000b ; break received FrmErr Equ 00001000b ; framing error ParErr Equ 00000100b ; parity error OveRun Equ 00000010b ; overrun error rdta Equ 00000001b ; received data ready AnyErr Equ BrkRcv+FrmErr+ParErr+OveRun ; ; 8250 MCR constants LpBk Equ 00010000b ; UART out loops to in (test) Usr2 Equ 00001000b ; Gates 8250 interrupts Usr1 Equ 00000100b ; aux user1 output SetRTS Equ 00000010b ; sets RTS output SetDTR Equ 00000001b ; sets DTR output ; ; 8250 MSR constants CDlvl Equ 10000000b ; carrier detect level RIlvl Equ 01000000b ; ring indicator level DSRlvl Equ 00100000b ; DSR level CTSlvl Equ 00010000b ; CTS level CDchg Equ 00001000b ; Carrier Detect change RIchg Equ 00000100b ; Ring Indicator change DSRchg Equ 00000010b ; DSR change CTSchg Equ 00000001b ; CTS change ; ; 8250 IER constants S_Int Equ 00001000b ; enable status interrupt E_Int Equ 00000100b ; enable error interrupt X_Int Equ 00000010b ; enable transmit interrupt R_Int Equ 00000001b ; enable receive interrupt Allint Equ 00001111b ; enable all interrupts Subttl Definitions for THIS Driver page ; ; Bit definitions for the output status byte ; ( this driver only ) LinIdl Equ 0ffh ; if all bits off, xmitter is idle LinXof Equ 1 ; output is suspended by XOFF LinDSR Equ 2 ; output is suspended until DSR comes on again LinCTS Equ 4 ; output is suspended until CTS comes on again ; ; Bit definitions for the input status byte ; ( this driver only ) BadInp Equ 1 ; input line errors have been detected LostDt Equ 2 ; receiver buffer overflowed, data lost OffLin Equ 4 ; device is off line now ; ; Bit definitions for the special characteristics words ; ( this driver only ) ; InSpec controls how input from the UART is treated ; InEpc Equ 0001h ; errors translate to codes with parity bit on ; ; OutSpec controls how output to the UART is treated ; OutDSR Equ 0001h ; DSR is used to throttle output data OutCTS Equ 0002h ; CTS is used to throttle output data OutXon Equ 0004h ; XON/XOFF is used to throttle output data OutCdf Equ 0010h ; carrier detect is off-line signal OutDrf Equ 0020h ; DSR is off-line signal ; Unit Struc ; each unit has a structure defining its state: Port Dw ? ; I/O port address Vect Dw ? ; interrupt vector offset (NOT interrupt number!) Isradr Dw ? ; offset to interrupt service routine OtStat Db Wd8 ; default LCR bit settings during INIT, ; output status bits after InStat Db Usr2+SetRTS+SetDTR ; MCR bit settings during INIT, ; input status bits after InSpec Dw InEpc ; special mode bits for INPUT OutSpec Dw OutXon ; special mode bits for OUTPUT Baud Dw 96 ; current baud rate divisor value (1200 b) Ifirst Dw 0 ; offset of first character in input buffer Iavail Dw 0 ; offset of next available byte Ibuf Dw ? ; pointer to input buffer Ofirst Dw 0 ; offset of first character in output buffer Oavail Dw 0 ; offset of next avail byte in output buffer Obuf Dw ? ; pointer to output buffer Unit Ends ; ; Beginning of driver code and data ; Driver Segment Assume Cs:driver, ds:driver, es:driver Org 0 ; drivers start at 0 Dw Async2,-1 ; pointer to next device Dw DevChr + DevIoc ; character device with IOCTL Dw Strtegy ; offset of Strategy routine Dw Request1 ; offset of interrupt entry point 1 Db 'ASY1 ' ; device 1 name Async2: Dw -1,-1 ; pointer to next device: MS-DOS fills in Dw DevChr + DevIoc ; character device with IOCTL Dw Strtegy ; offset of Strategy routine Dw Request2 ; offset of interrupt entry point 2 Db 'ASY2 ' ; device 2 name ;dbgptr dd 0b0000000h ; ; Following is the storage area for the request packet pointer ; PackHd Dd 0 ; ; baud rate conversion table Asy_baudt Dw 50,2304 ; first value is desired baud rate Dw 75,1536 ; second is divisor register value Dw 110,1047 Dw 134, 857 Dw 150, 786 Dw 300, 384 Dw 600, 192 Dw 1200, 96 Dw 1800, 64 Dw 2000, 58 Dw 2400, 48 Dw 3600, 32 Dw 4800, 24 Dw 7200, 16 Dw 9600, 12 ; table of structures ; ASY1 defaults to the COM1 port, INT 0CH vector, XON, ; no parity, 8 databits, 1 stop bit, and 1200 baud Asy_tab1: Unit <3f8h,30h,asy1isr,,,,,,,,in1buf,,,out1buf> ; ASY2 defaults to the COM2 port, INT 0BH vector, XON, ; no parity, 8 databits, 1 stop bit, and 1200 baud Asy_tab2: Unit <2f8h,2ch,asy2isr,,,,,,,,in2buf,,,out2buf> Bufsiz Equ 256 ; input buffer size Bufmsk = Bufsiz-1 ; mask for calculating offsets modulo bufsiz In1buf Db Bufsiz DUP (?) Out1buf Db Bufsiz DUP (?) In2buf Db Bufsiz DUP (?) Out2buf Db Bufsiz DUP (?) ; ; Following is a table of offsets to all the driver functions Asy_funcs: Dw Init ; 0 initialize driver Dw Mchek ; 1 media check (block only) Dw BldBPB ; 2 build BPB (block only) Dw Ioctlin ; 3 IOCTL read Dw Read ; 4 read Dw Ndread ; 5 nondestructive read Dw Rxstat ; 6 input status Dw Inflush ; 7 flush input buffer Dw Write ; 8 write Dw Write ; 9 write with verify Dw Txstat ; 10 output status Dw Txflush ; 11 flush output buffer Dw Ioctlout ; 12 IOCTL write ; Following are not used in this driver..... Dw Zexit ; 13 open (3.x only, not used) Dw Zexit ; 14 close (3.x only, not used) Dw Zexit ; 15 rem med (3.x only, not used) Dw Zexit ; 16 out until bsy (3.x only, not used) Dw Zexit ; 17 Dw Zexit ; 18 Dw Zexit ; 19 generic IOCTL request (3.2 only) Dw Zexit ; 20 Dw Zexit ; 21 Dw Zexit ; 22 Dw Zexit ; 23 get logical drive map (3.2 only) Dw Zexit ; 24 set logical drive map (3.2 only) Subttl Driver Code Page ; ; The Strategy routine itself: ; Strtegy Proc Far ; dbg 'S','R',' ' Mov Word Ptr CS:PackHd,BX ; store the offset Mov Word Ptr CS:PackHd+2,ES ; store the segment Ret Strtegy Endp ; Request1: ; async1 has been requested Push Si ; save SI Lea Si,Asy_tab1 ; get the device unit table address Jmp Short Gen_request Request2: ; async2 has been requested Push Si ; save SI Lea Si,Asy_tab2 ; get unit table two's address Gen_request: ; dbg 'R','R',' ' Pushf ; save all regs Cld Push Ax Push Bx Push Cx Push Dx Push Di Push Bp Push Ds Push Es Push Cs ; set DS = CS Pop Ds Les Bx,PackHd ; get packet pointer Lea Di,Asy_funcs ; point DI to jump table Mov Al,es:code[bx] ; command code Cbw Add Ax,Ax ; double to word Add Di,ax Jmp [di] ; go do it ; ; Exit from driver request ; ExitP Proc Far Bsyexit: Mov Ax,StsBsy Jmp Short Exit Mchek: BldBPB: Zexit: Xor Ax,Ax Exit: Les Bx,PackHd ; get packet pointer Or Ax,StsDne Mov Es:Stat[Bx],Ax ; set return status Pop Es ; restore registers Pop Ds Pop Bp Pop Di Pop Dx Pop Cx Pop Bx Pop Ax Popf Pop Si Ret ExitP Endp Subttl Driver Service Routines Page ; Read data from device Read: ; dbg 'R','d',' ' Mov Cx,Es:Count[bx] ; get requested nbr Mov Di,Es:Xfer[bx] ; get target pointer Mov Dx,Es:Xseg[bx] Push Bx ; save for count fixup Push Es Mov Es,Dx Test InStat[si],BadInp Or LostDt Je No_lerr ; no error so far... Add Sp,4 ; error, flush SP And InStat[si],Not ( BadInp Or LostDt ) Mov Ax,ErrRf ; error, report it Jmp Exit No_lerr: Call Get_in ; go for one Or Ah,Ah Jnz Got_all ; none to get now Stosb ; store it Loop No_lerr ; go for more Got_all: Pop Es Pop Bx Sub Di,Es:Xfer[bx] ; calc number stored Mov Es:Count[bx],Di ; return as count Jmp Zexit ; Nondestructive read from device Ndread: Mov Di,ifirst[si] Cmp Di,iavail[si] Jne Ndget Jmp Bsyexit ; buffer empty Ndget: Push Bx Mov Bx,ibuf[si] Mov Al,[bx+di] Pop Bx Mov Es:media[bx],al ; return char Jmp Zexit ; Input status request Rxstat: Mov Di,ifirst[si] Cmp Di,iavail[si] Jne Rxful Jmp Bsyexit ; buffer empty Rxful: Jmp Zexit ; have data ; Input flush request Inflush: Mov Ax,iavail[si] Mov Ifirst[si],ax Jmp Zexit ; Output data to device Write: ; dbg 'W','r',' ' Mov Cx,es:count[bx] Mov Di,es:xfer[bx] Mov Ax,es:xseg[bx] Mov Es,ax Wlup: Mov Al,es:[di] ; get the byte Inc Di Wwait: Call Put_out ; put away Cmp Ah,0 Jne Wwait ; wait for room! Call Start_output ; get it going Loop Wlup Jmp Zexit ; Output status request Txstat: Mov Ax,ofirst[si] Dec Ax And Ax,bufmsk Cmp Ax,oavail[si] Jne Txroom Jmp Bsyexit ; buffer full Txroom: Jmp Zexit ; room exists ; IOCTL read request, return line parameters Ioctlin: Mov Cx,es:count[bx] Mov Di,es:xfer[bx] Mov Dx,es:xseg[bx] Mov Es,dx Cmp Cx,10 Je Doiocin Mov Ax,errbsl Jmp Exit Doiocin: Mov Dx,port[si] ; base port Mov Dl,Lctrl ; line status Mov Cx,4 ; LCR, MCR, LSR, MSR Getport: In Al,dx Stos Byte Ptr [DI] Inc Dx Loop Getport Mov Ax,InSpec[si] ; spec in flags Stos Word Ptr [DI] Mov Ax,OutSpec[si] ; out flags Stos Word Ptr [DI] Mov Ax,baud[si] ; baud rate Mov Bx,di Mov Di,offset Asy_baudt+2 Mov Cx,15 Baudcin: Cmp [di],ax Je Yesinb Add Di,4 Loop Baudcin Yesinb: Mov Ax,-2[di] Mov Di,bx Stos Word Ptr [DI] Jmp Zexit ; Flush output buffer request Txflush: Mov Ax,oavail[si] Mov Ofirst[si],ax Jmp Zexit ; IOCTL request: change line parameters for this driver Ioctlout: Mov Cx,es:count[bx] Mov Di,es:xfer[bx] Mov Dx,es:xseg[bx] Mov Es,dx Cmp Cx,10 Je Doiocout Mov Ax,errbsl Jmp Exit Doiocout: Mov Dx,port[si] ; base port Mov Dl,Lctrl ; line ctrl Mov Al,es:[di] Inc Di Or Al,Dlab ; set baud Out Dx,al Clc Jnc $+2 Inc Dx ; mdm ctrl Mov Al,es:[di] Or Al,Usr2 ; Int Gate Out Dx,al Add Di,3 ; skip LSR,MSR Mov Ax,es:[di] Add Di,2 Mov InSpec[si],ax Mov Ax,es:[di] Add Di,2 Mov OutSpec[si],ax Mov Ax,es:[di] ; set baud Mov Bx,di Mov Di,offset Asy_baudt Mov Cx,15 Baudcout: Cmp [di],ax Je Yesoutb Add Di,4 Loop Baudcout Mov Dl,Lctrl ; line ctrl In Al,dx ; get LCR data And Al,not Dlab ; strip Clc Jnc $+2 Out Dx,al ; put back Mov Ax,ErrUm ; "unknown media" Jmp Exit Yesoutb: Mov Ax,2[di] ; get divisor Mov Baud[si],ax ; save to report later Mov Dx,port[si] ; set divisor Out Dx,al Clc Jnc $+2 Inc Dx Mov Al,ah Out Dx,al Clc Jnc $+2 Mov Dl,Lctrl ; line ctrl In Al,dx ; get LCR data And Al,not Dlab ; strip Clc Jnc $+2 Out Dx,al ; put back Jmp Zexit Subttl Ring Buffer Routines Page Put_out Proc Near ; puts AL into output ring buffer Push Cx Push Di Pushf Cli Mov Cx,oavail[si] ; put ptr Mov Di,cx Inc Cx ; bump And Cx,bufmsk Cmp Cx,ofirst[si] ; overflow? Je Poerr ; yes, don't Add Di,obuf[si] ; no Mov [di],al ; put in buffer Mov Oavail[si],cx ; dbg 'p','o',' ' Mov Ah,0 Jmp Short Poret Poerr: Mov Ah,-1 Poret: Popf Pop Di Pop Cx Ret Put_out Endp Get_out Proc Near ; gets next character from output ring buffer Push Cx Push Di Pushf Cli Mov Di,ofirst[si] ; get ptr Cmp Di,oavail[si] ; put ptr Jne Ngoerr Mov Ah,-1 ; empty Jmp Short Goret Ngoerr: ; dbg 'g','o',' ' Mov Cx,di Add Di,obuf[si] Mov Al,[di] ; get char Mov Ah,0 Inc Cx ; bump ptr And Cx,bufmsk ; wrap Mov Ofirst[si],cx Goret: Popf Pop Di Pop Cx Ret Get_out Endp Put_in Proc Near ; puts the char from AL into input ring buffer Push Cx Push Di Pushf Cli Mov Di,iavail[si] Mov Cx,di Inc Cx And Cx,bufmsk Cmp Cx,ifirst[si] Jne Npierr Mov Ah,-1 Jmp Short Piret Npierr: Add Di,ibuf[si] Mov [di],al Mov Iavail[si],cx ; dbg 'p','i',' ' Mov Ah,0 Piret: Popf Pop Di Pop Cx Ret Put_in Endp Get_in Proc Near ; gets one from input ring buffer into AL Push Cx Push Di Pushf Cli Mov Di,ifirst[si] Cmp Di,iavail[si] Je Gierr Mov Cx,di Add Di,ibuf[si] Mov Al,[di] Mov Ah,0 ; dbg 'g','i',' ' Inc Cx And Cx,bufmsk Mov Ifirst[si],cx Jmp Short Giret Gierr: Mov Ah,-1 Giret: Popf Pop Di Pop Cx Ret Get_in Endp Subttl Interrupt Dispatcher Routine Page Asy1isr: Sti Push Si Lea Si,asy_tab1 Jmp Short Int_serve Asy2isr: Sti Push Si Lea Si,asy_tab2 Int_serve: Push Ax ; save all regs Push Bx Push Cx Push Dx Push Di Push Ds Push Cs ; set DS = CS Pop Ds Int_exit: ; dbg 'I','x',' ' Mov Dx,Port[si] ; base address Mov Dl,IntId ; check Int ID In Al,Dx Cmp Al,00h ; dispatch filter Je Int_modem Jmp Int_mo_no Int_modem: ; dbg 'M','S',' ' Mov Dl,Mstat In Al,dx ; read MSR content Test Al,CDlvl ; carrier present? Jnz Msdsr ; yes, test for DSR Test OutSpec[si],OutCdf ; no, is CD off line? Jz Msdsr Or InStat[si],OffLin Msdsr: Test Al,DSRlvl ; DSR present? Jnz Dsron ; yes, handle it Test OutSpec[si],OutDSR ; no, is DSR throttle? Jz Dsroff Or OtStat[si],LinDSR ; yes, throttle down Dsroff: Test OutSpec[si],OutDrf ; is DSR off line? Jz Mscts Or InStat[si],OffLin ; yes, set flag Jmp Short Mscts Dsron: Test OtStat[si],LinDSR ; throttled for DSR? Jz Mscts Xor OtStat[si],LinDSR ; yes, clear it out Call Start_output Mscts: Test Al,CTSlvl ; CTS present? Jnz Ctson ; yes, handle it Test OutSpec[si],OutCTS ; no, is CTS throttle? Jz Int_exit2 Or OtStat[si],LinCTS ; yes, shut it down Jmp Short Int_exit2 Ctson: Test OtStat[si],LinCTS ; throttled for CTS? Jz Int_exit2 Xor OtStat[si],LinCTS ; yes, clear it out Jmp Short Int_exit1 Int_mo_no: Cmp Al,02h Jne Int_tx_no Int_txmit: ; dbg 'T','x',' ' Int_exit1: Call Start_output ; try to send another Int_exit2: Jmp Int_exit Int_tx_no: Cmp Al,04h Jne Int_rec_no Int_receive: ; dbg 'R','x',' ' Mov Dx,port[si] In Al,dx ; take char from 8250 Test OutSpec[si],OutXon ; is XON/XOFF enabled? Jz Stuff_in ; no Cmp Al,'S' And 01FH ; yes, is this XOFF? Jne Isq ; no, check for XON Or OtStat[si],LinXof ; yes, disable output Jmp Int_exit2 ; don't store this one Isq: Cmp Al,'Q' And 01FH ; is this XON? Jne Stuff_in ; no, save it Test OtStat[si],LinXof ; yes, waiting? Jz Int_exit2 ; no, ignore it Xor OtStat[si],LinXof ; yes, clear the XOFF bit Jmp Int_exit1 ; and try to resume xmit Int_rec_no: Cmp Al,06h Jne Int_done Int_rxstat: ; dbg 'E','R',' ' Mov Dl,Lstat In Al,dx Test InSpec[si],InEpc ; return them as codes? Jz Nocode ; no, just set error alarm And Al,AnyErr ; yes, mask off all but error bits Or Al,080h Stuff_in: Call Put_in ; put input char in buffer Cmp Ah,0 ; did it fit? Je Int_exit3 ; yes, all OK Or InStat[si],LostDt ; no, set DataLost bit Int_exit3: Jmp Int_exit Nocode: Or InStat[si],BadInp Jmp Int_exit3 Int_done: Clc Jnc $+2 Mov Al,EOI ; all done now Out PIC_b,Al Pop Ds ; restore regs Pop Di Pop Dx Pop Cx Pop Bx Pop Ax Pop Si Iret Start_output Proc Near Test OtStat[si],LinIdl ; Blocked? Jnz Dont_start ; yes, no output Mov Dx,port[si] ; no, check UART Mov Dl,Lstat In Al,Dx Test Al,xhre ; empty? Jz Dont_start ; no Call Get_out ; yes, anything waiting? Or Ah,Ah Jnz Dont_start ; no Mov Dl,RxBuf ; yes, send it out Out Dx,al ; dbg 's','o',' ' Dont_start: ret Start_output Endp Subttl Initialization Request Routine Page Init: Lea Di,$ ; release rest... Mov Es:Xfer[bx],Di Mov Es:Xseg[bx],Cs Mov Dx,Port[si] ; base port Mov Dl,Lctrl Mov Al,Dlab ; enable divisor Out Dx,Al Clc Jnc $+2 Mov Dl,RxBuf Mov Ax,Baud[si] ; set baud Out Dx,Al Clc Jnc $+2 Inc Dx Mov Al,Ah Out Dx,Al Clc Jnc $+2 Mov Dl,Lctrl ; set LCR Mov Al,OtStat[si] ; from table Out Dx,Al Mov OtStat[si],0 ; clear status Clc Jnc $+2 Mov Dl,IntEn ; IER Mov Al,AllInt ; enable ints in 8250 Out Dx,Al Clc Jnc $+2 Mov Dl,Mctrl ; set MCR Mov Al,InStat[si] ; from table Out Dx,Al Mov InStat[si],0 ; clear status ClRgs: Mov Dl,Lstat ; clear LSR In Al,Dx Mov Dl,RxBuf ; clear RX reg In Al,Dx Mov Dl,Mstat ; clear MSR In Al,Dx Mov Dl,IntId ; IID reg In Al,Dx In Al,Dx Test Al,1 ; int pending? Jz ClRgs ; yes, repeat Cli Xor Ax,Ax ; set int vec Mov Es,Ax Mov Di,Vect[si] Mov Ax,IsrAdr[si] ; from table Stosw Mov Es:[di],cs In Al,PIC_e ; get 8259 And Al,0E7h ; com1/2 mask Clc Jnb $+2 Out PIC_e,Al Sti Mov Al,EOI ; now send EOI just in case Out PIC_b,Al ; dbg 'D','I',' ' ; driver installed Jmp Zexit Driver Ends End