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Assembly Source File | 1985-09-13 | 25.4 KB | 546 lines

Page 60,132 .Radix 16 Title Communications Interface Routine Subttl Macros Page Save Macro R1,R2,R3,R4,R5,R6,R7,R8,R9,R10 Irp Rx,<R1,R2,R3,R4,R5,R6,R7,R8,R9,R10> ;Repeat for each parm Ifnb <Rx> ;If this parm not blank Push Rx ;Save the register Endif ;End Ifnb Endm ;End Irp ;; The Restore macro makes use of the fact that R1-R10 are still defined, ;; but, being a different macro, this will not expand when the Save macro ;; is used. Note that the Restore macro will restore whatever registers ;; were last Save'd in the assembly listing, not during execution. ;; Therefore, its use is restricted to restoring the previous sequential ;; Save macro's registers. Restore Macro Irp Rx,<R10,R9,R8,R7,R6,R5,R4,R3,R2,R1> ;Repeat for each parm Ifnb <Rx> ;If this parm not blank Pop Rx ;Pop the register Endif ;End Ifnb Endm ;End Irp Endm ;End of Restore macro Endm ;End of Save Macro Setint Macro Vector,Routine ;Sets an interrupt vector Lea DX,Routine ;Address the routine Mov AX,25*100+Vector ;Set the vector Int 21 ;Call DOS to do it Endm Incbuf Macro Buffer Local Notend ;Not at end of buffer label ;; Macro to increment the buffer pointer. This macro is used ;; internally by other buffer processing macros. The pointer to ;; be incremented must be in BX. Results in BX. Inc BX ;Point at next character Cmp BX,Offset Buffer.Buff + Length Buff ;At end of buffer? Jb Notend ;No - continue Lea BX,Buffer.Buff ;Point back to start of buffer Notend Label Near ;Not at end of buffer Endm ;End of macro Bufinit Macro Buffer ;Initialize the buffers ;; This macro must be called once for each buffer. It's purpose ;; is to ensure the pointers are set up correctly before the ;; buffers are used. Unless the buffers are initialized, the ;; results will be unpredictable. Lea BX,Buffer.Buff ;Get address of buffer Mov Buffer.Staptr,BX ;Set start of data address Mov Buffer.Endptr,BX ;End of data too (buffer empty) Endm ;End of macro Putbuf Macro Buffer ;Insert a character in the buffer Local Bufull ;; This macro puts a byte into BUFFER. Origin is AL, and it uses the ;; BX reg. The carry flag is set if the buffer is full and the routine ;; cannot place a bit in the buffer, and is cleared if the character is ;; inserted in the buffer and pointers updated. ;; The buffer must have been defined with the BUFFER structure. Mov BX,Buffer.Endptr ;Get pointer to end of buffer Incbuf Buffer ;Point at next character Cmp BX,Buffer.Staptr ;Buffer full? Je Bufull ;Yes - buffer overrun Mov [BX],AL ;Store a byte Mov Buffer.Endptr,BX ;Replace new pointer Stc ;Inverse of carry flag returned Bufull Label Near ;Get a character from the buffer Cmc ;Invert carry bit for return code Endm ;End of macro Getbuf Macro Buffer ;Get a character from the buffer Local Bufemp ;; This macro gets a character from BUFFER and returns it in AL. It ;; uses the BX reg. Carry flag is set if the buffer is empty, and ;; cleared if a character is returned in AL. ;; The buffer must have been defined with the BUFFER structure. Mov BX,Buffer.Staptr ;Get buffer data start Cmp BX,Buffer.Endptr ;Any data in buffer? Je Bufemp ;Yes - go transmit it Incbuf Buffer ;Point at next character Mov AL,[BX] ;Get a byte Mov Buffer.Staptr,BX ;Restore pointer Stc ;Set complement of carry flag Bufemp Label Near Cmc ;Set true return flag Endm Flush Macro Buffer ;Flush the buffer ;; This macro will flush BUFFER by setting the start and end ;; pointers equal. It uses the BX reg. Mov BX,Buffer.Staptr ;Get start of data Mov Buffer.Endptr,BX ;Set end = start (empty) Endm ; Structure used for buffer definition. ; Staptr = Endptr means buffer is full. Otherwise buffer has data ; in it. Buffer Struc Buff Db 256d Dup (0) ;Buffer size in decimal Staptr Dw 0 ;Start of data pointer Endptr Dw 0 ;End of data pointer Buffer Ends Inital Record Speed:3, Parity:2, Stop:1, Len:2 ;Init call parms in AL Subttl Equates Page ; Line status bits -- AH Timeout Equ 80 ;Time out error Tbufemp Equ 40 ;Transmit buffer empty Tbufnfl Equ 20 ;Transmit buffer not full Brkdet Equ 10 ;Break detect Framerr Equ 08 ;Framing error Parerr Equ 04 ;Parity error Rcveovr Equ 02 ;Receive buffer overrun Rdatrdy Equ 01 ;Receive buffer has data ; Modem status bits -- AL Rlsd Equ 80 ;Received line signal detect Ri Equ 40 ;Ring indicator Dsr Equ 20 ;Data set ready Cts Equ 10 ;Clear to send Drlds Equ 08 ;Delta receive line signal detect Teri Equ 04 ;Trailing edge ring indicator Ddsr Equ 02 ;Delta data set ready Dcts Equ 01 ;Delta clear to send ; Interrupt Enable reg bit definitions Msint Equ 08 ;Modem status int bit Rlsint Equ 04 ;Receive line status int bit Thrint Equ 02 ;Transmit holding reg empty int bit Daint Equ 01 ;Data availalbe interrupt ; Modem Control Port Out2 Equ 08 ;Out2 bit Out1 Equ 04 ;Out1 bit Rts Equ 02 ;Request to Send Dtr Equ 01 ;Data Terminal Ready ; Other equates and records Asysmsk Equ 10 ;System interrupt (port 21) mask Perror Equ -1 ;Paramater error Baseadr Equ 3F8 ;Comm port 1 base address Subttl Constants Page + Comm Segment Para Public 'Code' Assume CS:Comm ,DS:Comm ,ES:nothing ,SS:Nothing Org 100h ;Set starting point Entry Label Near ;Initialization entry point Jmp Start ;Go to initialization code Db 'Asynchronous Communications Port Driver ' Db '(C) Copyright 1985 by Jerry D. Stuckle.' Db 'Released to Public Domain for non-business use only.' Divisor Label Word ;Table of divisor values Dw 1047d ; 110 baud Dw 768d ; 150 baud Dw 384d ; 300 baud Dw 192d ; 600 baud Dw 96d ;1200 baud Dw 48d ;2400 baud Dw 24d ;4800 baud Dw 12d ;9600 baud Functbl Label Word ;Function request table of routines Dw Copen ;AH = 0 Open communications port Dw Csend ;AH = 1 Send a character Dw Crcve ;AH = 2 Receive a character Dw Cstat ;AH = 3 Get buffer status Dw Cclos ;AH = 4 Close communications port Funcnt Equ ($ - Functbl) / 2 ;Number of words in table Subttl Data Areas Page ; Transmit and receive buffer structures Xmit Buffer <,,> ;No override for initial values Rcve Buffer <,,> ;No override for initial values Lstatus Db 0 ;Line status byte Mstatus Db 0 ;Modem status byte Subttl Interface Routines Page Int14 Proc Near ;Interrupt 14 input Sti ;Other interrupts are OK here. Save DS,DX,SI,DI,BX ;Save all required regs Push CS ;Place CS on stack so... Pop DS ;...we can set DS Or DX,DX ;Is DX 0? Jnz Parmerr ;No - error found - return Cmp AH,Funcnt ;Check against number of entries in.. Ja Parmerr ;..the table and branch if too high. Mov DX,Baseadr ;Get port base address Xor BH,BH ;One byte index being used Mov BL,AH ;Get function code Shl BX,1 ;Multiply by 2 Call Functbl[BX] ;Call the correct routine Jmp Short Intret ;Go return to caller Parmerr Label Near ;Paramater error detected Mov AH,Perror ;Move in error code Intret Label Near ;Return to caller Restore ;Put back all registers Iret ;Interrupt return Int14 Endp ;End of mainline code Subttl Open the Comm port Page Copen Proc Near Mov AH,AL ;Save parms in AH Add DX,3 ;Point at line control reg In AL,DX ;Get the reg in AL Or AL,80 ;Turn on Divisor Latch Bit Out DX,AL ;Enable the latch Sub DX,3 ;Point back to base port Xor BH,BH ;Insure BH is low values Mov BL,AH ;Get all init parms in BL And BL,Mask Speed ;Turn off excess bits Mov CL,Speed ;Get the shift value Shr BL,CL ;And move it over. Shl BL,1 ;X2 for index into word table Lea SI,Divisor[BX] ;Set pointer to correct divisor Lodsb ;Get the low order of the divisor Out DX,AL ;Set into the divisor latch Lodsb ;Get the high order of the divisor Inc DX ;Point to the high order port Out DX,AL ;And set latch high order Inc DX ;Now back to the... Inc DX ;...DLAB bit Mov AL,AH ;Get the original parms in AL And AL,Mask Parity + Mask Stop + Mask Len ;Leave on only desired bits. ; Now magically, the rest of the bits in AL match exactly ; the Line Control Register bits (maybe it was planned?). Out DX,AL ;And set the other parms in the LCR ; Now we have all the requested parms set, all that remains is to ; set DTR and RTS, and enable the interrupts on the async board ; and from the system (port 21). Note that this uses negative logic ; (a bit being '0' means this interrupt is active). Push DX ;Save base address on stack Mov DX,21 ;Address interrupt control reg In AL,DX ;Get current interrupts And AL,0FF-Asysmsk ;Allow Async interrupts from port 1 Out DX,AL ;Put it back out Pop DX ;Restore base addr from stack Inc DX ;Point to Modem Control Reg Mov AL,Out2+Rts+Dtr ;RTS and DTR Out DX,AL ;Set the Modem Control Reg Sub DX,3 ;Back up to Interupt Enable Reg In AL,DX ;Port might already be set. Or AL,Msint+Rlsint+Daint ;Modem status+Line status+Data avail Out DX,AL ;Set the reg Nop ;Allow dummy machine cycle ; Disable all interrupts before flushing buffers and getting status. Cli ;Disable again Flush Xmit ;Flush the transmit buffer Flush Rcve ;Flush the receive buffer Add DX,4 ;Point to Line Status Reg In AL,DX ;Get the status In AL,DX ;Do it again to clear any errors Mov Lstatus,AL ;Set the status byte Inc DX ;Point to Modem Status Reg In AL,DX ;Get the status In AL,DX ;Again to clear any delta bits Mov Mstatus,AL ;Set current modem status Sti ;All done with buffers - enable ints Call Cstat ;Allow Cstat to set status Ret ;Return to caller Copen Endp Subttl Put character in AL into buffer Page Csend Proc Near ;Put the character in AX Putbuf Xmit ;Put AL to the transmit buffer Jc Csend2 ;If carry, return buffer full Inc DX ;Point at Interrupt enable register In AL,DX ;Get the port Test AL,Thrint ;Is transmit already enabled? Jnz Csend1 ;Yes - return Or AL,Thrint ;Enable xmit hold reg interrupt Out DX,AL ;And put it back out Csend1 Label Near Dec DX ;Point back to base address Call Ahstat ;Get status in AH And AH,0FF-Timeout ;Turn off timeout bit Ret ;Return to caller Csend2 Label Near Call Ahstat ;Get status in AH Or AH,Timeout ;Set timeout bit (can't send) Ret ;Return to caller Csend Endp Subttl Receive a character from the buffer into AL Page Crcve Proc Near Getbuf Rcve Jc Crcve1 ;If buffer empty, return FF in AH Call Ahstat ;Get status in AH And AH,Timeout+Brkdet+Framerr+Parerr+Rcveovr ; Only error bits Ret ;And return to caller Crcve1 Label Near Mov AH,-1 ;Indicate buffer empty Ret ;And return to caller Crcve Endp Subttl Get port status Page Cstat Proc Near Call Ahstat ;Get line status in AH Mov AL,Mstatus ;Get modem status Ret ;And return to caller Ahstat Proc Near Xor AH,AH ;New line status (0) Xchg AH,Lstatus ;Get line status and reset it ; Set the Transmit buff Mov BX,Xmit.Endptr ;Get start pointer Cmp BX,Xmit.Staptr ;If Endptr = Staptr, Buffer empty Jne Ahstat1 ;If not empty, check if full Or AH,Tbufemp+Tbufnfl ;Turn on empty and not full Jmp Short Ahstat2 ;Check receive buffer Ahstat1 Label Near ;Transmit not empty, check if full Incbuf Xmit ;Point at next character Cmp BX,Xmit.Staptr ;Equal to start of buffer? Je Ahstat2 ;Yes - buffer is full. Continue. Or AH,Tbufnfl ;Not full, so set the bit. Ahstat2 Label Near Mov BX,Rcve.Staptr ;Get start pointer Cmp BX,Rcve.Endptr ;If Start = End, buffer empty Jne Ahstat3 ;If empty, continue Ret ;Else all done, so return to caller ; Now we have all the bits in AH set, so lets return to the caller. Ahstat3 Label Near Or AH,Rdatrdy ;Set receive data ready Ret ;Return to caller Ahstat Endp Cstat Endp Subttl Close the Comm Port and flush the buffers Page Cclos Proc Near Xor AL,AL ;No interrupts Inc DX ;Point at IER Out DX,AL ;Disable the interrupts Push DX ;Save IER address on stack Mov DX,21 ;System interrupt mask In AL,DX ;Get the port Or AL,Asysmsk ;Disable the interrupt Out DX,AL ;And put it back to the port Pop DX ;Restore origingal value of DX Add DX,3 ;Point at Modem control reg Out DX,AL ;Turn off all bits Sub DX,3 ;Back to base address Flush Xmit ;Clear the transmit buffer Flush Rcve ;Clear the receive buffer Ret ;And return to caller Cclos Endp Subttl Interrupt handlers Page + ;********************************************************************** ;* * ;* ASYNC INTERRUPT HANDLERS * ;* * ;********************************************************************** Int0C Proc Near Sti ;Allow interrupts Save AX,BX,DX,DS ;Save the regs Mov DX,20 ;System interrupt controller Mov AL,20 ;Reset interrupt pending Out DX,AL ;Put back to system controller Push CS ;Put CS into stack... Pop DS ;And pop it back into DS Mov DX,Baseadr ;Get address of async port Inc DX ;Point at... Inc DX ;...Interrupt ID reg Intloop Label Near ;Handle interrupts loop In AL,DX ;Get interrupt type Test AL,1 ;Any interrupt pending? Jnz Asynrtn ;No - return Xor BH,BH ;Prepare for indexed call Mov BL,AL ;Interrupt code to index reg Push DX ;Save DX across call Call Inttbl[BX] ;Call the correct routine Pop DX ;Restore original DX Jmp Intloop ;Loop until all interrupts handled. Asynrtn Label Near Restore Iret ;Return from interrupt Inttbl Label Word Dw Modemst ;Modem status interrupt Dw Xmithrg ;Transmit holding reg empty Dw Rdatint ;Receive data available Dw Rcvrlst ;Receiver line status Subttl Get the modem status Page Modemst Proc Near ;Modem status Add DX,4 ;Point at modem status reg In AL,DX ;Read it Mov Mstatus,AL ;Place in status byte Ret ;Return to caller Modemst Endp Subttl Transmit a character from the buffer Page Xmithrg Proc Near ;Xmit hold reg empty Dec DX ;Point at IER Cli ;Disable while working with buffer Getbuf Xmit ;Get a character from the buffer Jc Xmithr1 ;No - disable transmit interrupts Dec DX ;Point at transmit holding reg Out DX,AL ;Put it out Sti ;Enable interrupts Ret ;Return to caller Xmithr1 Label Near In AL,DX ;Get the interrupt reg And AL,0FF-Thrint ;Turn off xmit holing reg bit Out DX,AL ;And send it back out Sti ;Re-enable interrupts Ret ;Return to caller Xmithrg Endp Subttl Receive a byte into the buffer Page Rdatint Proc Near Dec DL ;Point to ... Dec DX ;... data reg Cli ;Disable interrupts In AL,DX ;Get a byte Test Lstatus,Parerr ;Parity error this byte? Jz Rdatpok ;No, parity OK Or AL,80h ;Bad parity, set high bit in AL And Lstatus,0FFh-Parerr ;Turn off parity error Rdatpok Label Near Putbuf Rcve ;Put into receive buffer Jc Rcve2 ;If full, set overrun bit Sti Ret ;Return to caller Rcve2 Label Near Sti ;Enable interrupts again Or Lstatus,Rcveovr ;Set overrun Ret ;And return to caller Rdatint Endp Subttl Receiver line status interrupt Page Rcvrlst Proc Near Add DL,3 ;Point at line status reg In AL,DX ;Go read it And Lstatus,Rcveovr ;Turn off all but overrun bit And AH,0FF-(Tbufemp+Tbufnfl+Rcveovr+Rdatrdy) ;Unwanted bits off Or Lstatus,AL ;And turn on new status bits Ret ;Return to caller Rcvrlst Endp Int0C Endp Resend Equ $ ;Resident code ends here Subttl Initialization routine Page + Start Proc Near ;Initialization code ; First of all, initialize the buffers Bufinit Xmit Bufinit Rcve ; Now let's set the interrupt handlers Setint 0C,Int0C ;Port 1 Interrupt and routine Setint 14,Int14 ;Program interface interrupt ; And finally, terminate but leave resident code ; Use the old Int 27 call for DOS 1.x compatability. Lea DX,Resend ;Address end of resident section Int 27 ;Use Int 27 for DOS 1.0 Compatability Start Endp ;End of procedure Comm Ends End Entry