Ham Radio 2000 #1

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Assembly Source File | 1991-02-16 | 35.8 KB | 758 lines

;==========================================================================; ; 8250 Services ; ; This code also used by the QUADRAM QUADPORT board and the ; ; 4 async port card without change. ; ; ; ; Copyright 1983 by William E. Westfield. All rights reserved. ; ; Copyright 1986, 1987, 1988, 1991 by H. Roy Engehausen. ; ; All rights reserved. ; ; ; ; This software may be freely distributed and used, but it may not ; ; under any circumstances be sold by anyone other than the author. ; ; It may be distributed by a commercial company as long as it is ; ; for no cost. ; ; ; ;==========================================================================; ;--------------------------------------------------------------------------; ; Branch to the proper service routine ; ; ; ; AH=0 INITIALIZE ; ; DX is the port number. (0 = COM1, 1 = COM2) ; ; AL is set according to the following table. ; ; ; ; High speed option is off ; ; MSB LSB ; ; 7 6 5 4 3 2 1 0 ; ; ----data-rate---- -Parity-- Stopbits --Word length-- ; ; ; ; 000 - 110 X0 - none 0 - 1 10 - 7 bits ; ; 001 - 150 01 - odd 1 - 2 11 - 8 bits ; ; 010 - 300 11 - even ; ; 011 - 600 ; ; 100 - 1200 ; ; 101 - 2400 ; ; 110 - 4800 ; ; 111 - 9600 ; ; ; ; High speed option is on ; ; 000 - 9600 X0 - none 0 - 1 10 - 7 bits ; ; 001 - 14400 01 - odd 1 - 2 11 - 8 bits ; ; 010 - 19200 11 - even ; ; 011 - 28800 ; ; 100 - 38400 ; ; 101 - 57600 ; ; 110 - 115200 ; ; 111 - 330400 ; ; ; ; Returns: ; ; AX = status according to function 3. ; ; DX = unchanged ; ; ; ; AH=1 SEND ; ; DX is the port number. (0 = COM1, 1 = COM2) ; ; AL is the character to be sent. ; ; Returns: ; ; AH = status according to function 3. ; ; AL = unchanged ; ; DX = unchanged ; ; ; ; AH=2 RECEIVE ; ; DX is the port number. (0 = COM1, 1 = COM2) ; ; ; ; Returns: ; ; AH = status according to function 3. ; ; AL = character read from buffer. ; ; DX = unchanged ; ; ; ; AH=3 STATUS ; ; DX is the port number. (0 = COM1, 1 = COM2) ; ; ; ; Returns: ; ; AH = Line Status Register ; ; AL = Modem Status Register ; ; DX = Unchanged ; ; ; ; If the extended 8250 functions are available, they are described later ; ;--------------------------------------------------------------------------; MOV BL,AH IF present_8250x CMP BL,12 ; Validate the function code ELSE CMP BL,3 ; Validate the function code ENDIF JA rsint_8250_exit ; Not a valid code SUB BH,BH ; Zero the high order byte SHL BL,1 ; * 2 JMP rsint_8250_jmp[BX] ; Go to it rsint_8250_jmp LABEL WORD ; DW OFFSET rsint_8250_init ; 0 = Initialize DW OFFSET rsint_8250_send ; 1 = Send a character DW OFFSET rsint_8250_recv ; 2 = Receive character DW OFFSET rsint_8250_status ; 3 = Status IF present_8250x ; Extended function codes DW OFFSET rsint_8250_inquiry ; 4 = return footprint DW OFFSET rsint_8250_droprts ; 5 = signal NO RTS/DTR DW OFFSET rsint_8250_raiserts ; 6 = signal RTS/DTR DW OFFSET rsint_8250_sendbrk ; 7 = send break DW OFFSET rsint_8250_ndr ; 8 = non destructive read DW OFFSET rsint_8250_sopt ; 9 = set options DW OFFSET rsint_8250_buffw ; A = block write DW OFFSET rsint_8250_buffr ; B = block read DW OFFSET rsint_8250_ded ; C = DED mode send/receive ENDIF rsint_8250_exit: JMP rsint_exit ; ;==========================================================================; ; 8250 Bios constants ; ;==========================================================================; ;--------------------------------------------------------------------------; ; Divisors for the different data rates. The offset into the table ; ;is the one from the IBM BIOS initialization parameters ; ;--------------------------------------------------------------------------; divisor_8250 LABEL WORD ; DW 1047 ; 0 = 110 DW 768 ; 1 = 150 DW 384 ; 2 = 300 DW 192 ; 3 = 600 DW 96 ; 4 = 1200 DW 48 ; 5 = 2400 DW 24 ; 6 = 4800 DW 12 ; 7 = 9600 ; High speed options DW 12 ; 0 = 9600 DW 9 ; 1 = 14400 DW 6 ; 2 = 19200 DW 4 ; 3 = 28800 DW 3 ; 4 = 38400 DW 2 ; 5 = 57600 DW 1 ; 6 = 115200 DW 0 ; 7 = 330400 ;==========================================================================; ; Initialization routine ; ;==========================================================================; rsint_8250_init: ;--------------------------------------------------------------------------; ; Mark block as open ; ;--------------------------------------------------------------------------; OR flags[SI],flags_in_use ; This block is open! ;--------------------------------------------------------------------------; ; Set data rate ; ;--------------------------------------------------------------------------; MOV AH,AL ; Save the parms for later MOV BL,AH ; Look up the baud rate MOV CL,4 ; parameter ROL BL,CL ; AND BX,00001110B ; TEST options[SI],opt_high ; High speed option? JZ rsint_8250_init_nohs ; Nope ADD BX,00010000B ; Yep.. Offset rsint_8250_init_nohs: ; MOV BX,divisor_8250[BX] ; MOV CX,baseaddr[SI] ; Get base address for chip MOV DX,CX ; Address of LCR ADD DX,lcr_8250 ; MOV AL,lcr_8250_dlab ; Enable access to divisor OUT DX,AL ; MOV DX,CX ; Address of lower divisior half ADD DX,dll_8250 ; MOV AL,BL ; Put lower half OUT DX,AL ; MOV DX,CX ; Address of upper divisior half ADD DX,dlm_8250 ; MOV AL,BH ; Put upper half OUT DX,AL ; ;--------------------------------------------------------------------------; ; Set the data bits, stop bits, and parity ; ;--------------------------------------------------------------------------; MOV AL,AH ; Get parms back AND AL,00011111B ; Throw away baud rate leaving the rest MOV DX,CX ; Address of LCR ADD DX,lcr_8250 ; OUT DX,AL ; Output the parms ;--------------------------------------------------------------------------; ; Set interrupt enable register ; ;--------------------------------------------------------------------------; MOV AL,ier_8250_rda ; Enable data interrupt only TEST options[SI],opt_trbuf ; Transmit buffering turned on? JZ rsint_8250_initnotr ; No - Just want only 1 interrupt OR AL,ier_8250_thre+ier_8250_ms ; Yes - We need both modem status enable ; and THRE interrupts too rsint_8250_initnotr: MOV DX,CX ; Compute port address for the IER ADD DX,ier_8250 ; OUT DX,AL ; Set the IER ;--------------------------------------------------------------------------; ; Done with initialization ; ;--------------------------------------------------------------------------; JMP rsint_8250_status ; Now just status please ;==========================================================================; ; Send a character ; ;==========================================================================; ;--------------------------------------------------------------------------; ; There are two places where the branch from the non-interrupt ; ; driven code to the interrupt driven code is taken so be careful ; ;--------------------------------------------------------------------------; rsint_8250_send: MOV AH,AL ; Save the character to send MOV CX,baseaddr[SI] ; Get base address for chip ;--------------------------------------------------------------------------; ; Two separate routines, one for trasmit buffering and one if not! ; ;--------------------------------------------------------------------------; TEST options[SI],opt_trbuf ; Transmit buffering turned on? JNZ rsint_8250_send_bh ; Yes.. go there now! ;--------------------------------------------------------------------------; ; Unbuffered send ; ;--------------------------------------------------------------------------; CALL rsint_8250_send_unb ; Send unbuffered JMP rsint_8250_status ; Go do a status ;--------------------------------------------------------------------------; ; Buffered send starts here ; ;--------------------------------------------------------------------------; rsint_8250_send_bh: CLI ; Prevent status change TEST options[SI],opt_hdwhs ; Hardware handshaking desired? JZ rsint_8250_sendb_ok ; Nope ;--------------------------------------------------------------------------; ; Buffered send -- hardware handshaking. If the remote says no, go ; ; immediately to buffered send ; ;--------------------------------------------------------------------------; CALL rsint_8250_msr ; Get the MSR AND AL,msr_8250_cts ; CTS on? JZ rsint_8250_sendb_fb ; Go to a spot where buffering is forced ;--------------------------------------------------------------------------; ; This section is entered when its ok to send a character if the ; ; buffer is empty. Its either entered by the buffer handler above ; ; when handshaking is enabled and the remote says go or from the ; ; non-interrupt driven code if there is no handshaking ; ;--------------------------------------------------------------------------; rsint_8250_sendb_ok: ;--------------------------------------------------------------------------; ; Here we determine if the buffer is empty. If it is, we can send ; ; something right now. ; ;--------------------------------------------------------------------------; MOV BX,buffer_t_in[SI] ; Get buffer input pointer CMP BX,buffer_t_out[SI] ; See where the out pointer is JNE rsint_8250_sendb_fb2; If they are not equal then we have ; data in the buffer MOV DX,CX ; Compute port address for the LSR ADD DX,lsr_8250 ; IN AL,DX ; Get the LSR into AX AND AL,lsr_8250_thre ; THR empty? JZ rsint_8250_sendb_fb2; No.. Put character into the buffer STI ; AOK now ; If we get here, the buffer is empty, the transmitter is ready, and ; handshaking says it is ok to go! CALL rsint_8250_send_subr ; Send the character JMP SHORT rsint_8250_send_exit ; Now jump down to leave ;--------------------------------------------------------------------------; ; This code puts the data into the buffer. ; ;--------------------------------------------------------------------------; rsint_8250_sendb_fb: ; Use this entry point if hardware ; handshake says distant end is not ready ; We have to do some setup MOV BX,buffer_t_in[SI] ; Get buffer input pointer rsint_8250_sendb_fb2: ; Use this entry point if hardware ; handshake was ok or not enabled. ; All the setup is done when we get here MOV ES,buffer_t_a[SI] ; Get buffer segment MOV ES:[BX],AH ; Get character into buffer.. ;--------------------------------------------------------------------------; ; Bump the input pointer and handle the special case of where we wrap ; ; from one end of the buffer into the other ; ;--------------------------------------------------------------------------; INC BX ; Bump pointer CMP BX,buffer_size ; Have we wrapped the buffer? JL rsint_8250_sendb_bump ; No.. All done SUB BX,BX ; Yes.. Reset pointer rsint_8250_sendb_bump: MOV buffer_t_in[SI],BX ; Save pointer STI ; OK for changes now... ;--------------------------------------------------------------------------; ; If we have a destructive overlay possible then loop waiting for it to ; ; clear. Since the pointer in BX is to the location of the next character ; ; the we will overlap if it is the same as the pointer for the next ; ; character to send. The actual sending will be done by the interrupt ; ; handler. All we have to do is waint until the interrupt handler ; ; has cleaned some characters out of the buffer ; ;--------------------------------------------------------------------------; rsint_8250_sendb_bad: CMP BX,buffer_t_out[SI] ; See where the out pointer is IF present_dv ; Put in the desqview wait hook as needed JNE rsint_8250_send_exit ; If they are not equal then we are ok dv_cnt = dv_cnt + 1 dv_hook %dv_cnt CALL desqview JMP SHORT rsint_8250_sendb_bad ELSE JE rsint_8250_sendb_bad ; If they are not equal then we are ok ENDIF ;--------------------------------------------------------------------------; ; We come here when we have sent the character immediately. ; ;--------------------------------------------------------------------------; rsint_8250_send_exit: ;--------------------------------------------------------------------------; ; All done, do a status ; ;--------------------------------------------------------------------------; JMP rsint_8250_status ; Do a status ;--------------------------------------------------------------------------; ;--------------------------------------------------------------------------; ; Subroutine to send unbuffered ; ;--------------------------------------------------------------------------; rsint_8250_send_unb: TEST options[SI],opt_hdwhs ; Hardware handshaking desired? JZ rsint_8250_send_nbok ; Nope IF present_dv ; JMP SHORT rsint_8250_send_nbl_dv ; First time jump over dv hook ENDIF ; Hardware handshake loop for unbuffered sending rsint_8250_send_nbl: ; Loop here until we can send IF present_dv ; Put in the desqview wait hook as needed dv_cnt = dv_cnt + 1 dv_hook %dv_cnt CALL desqview rsint_8250_send_nbl_dv: ; Enter loop here when in desqview ENDIF CALL rsint_8250_msr ; Get the MSR AND AL,msr_8250_cts ; CTS on? JZ rsint_8250_send_nbl ; No.. Loop back rsint_8250_send_nbok: ; ; Unbuffered sending.. Now ready to transmit ; ***** FALL THRU ;--------------------------------------------------------------------------; ;--------------------------------------------------------------------------; ; Subroutine to send the character in AH ; ; *** WARNING *** also entered by fall thru from above ; ;--------------------------------------------------------------------------; rsint_8250_send_subr: ;--------------------------------------------------------------------------; ; Loop waiting for TBE ; ;--------------------------------------------------------------------------; MOV DX,CX ; Compute port address for the LSR ADD DX,lsr_8250 ; IF present_dv ; Put in the desqview wait hook as needed JMP SHORT rsint_8250_send_sublp_dv ; First time jump over dv hook ENDIF rsint_8250_send_sublp: ; Loop here until we can send IF present_dv ; Put in the desqview wait hook as needed dv_cnt = dv_cnt + 1 dv_hook %dv_cnt CALL desqview rsint_8250_send_sublp_dv: ; First time we jump here in desqview mode ENDIF IN AL,DX ; Get the LSR into AX AND AL,lsr_8250_thre ; THR empty? JZ rsint_8250_send_sublp ; No.. Loop back ;--------------------------------------------------------------------------; ; Out the character ; ;--------------------------------------------------------------------------; MOV AL,AH ; Get ready to out character MOV DX,CX ; Compute port address for the THR ; ADD DX,thr_8250 ; and then OUT DX,AL ; out the character ; The add of THR is commented out since the THR is at zero from ; the base. This just documents the fact we are going for the THR ;--------------------------------------------------------------------------; ; Turn on the character sent flag ; ;--------------------------------------------------------------------------; OR flags[SI],flags_xmt_on ; Turn on transmitter flag RET ; Return to sender ;==========================================================================; ; Receive a character ; ;==========================================================================; rsint_8250_recv: MOV CX,baseaddr[SI] ; Get base address for chip ;--------------------------------------------------------------------------; ; Loop waiting for something to appear in the buffer. We do this ; ; by comparing the input and output pointers. If they are the same ; ; same then there is nothing in the buffer ; ;--------------------------------------------------------------------------; MOV BX,buffer_r_out[SI] ; Get buffer output pointer IF present_dv ; If desqview presentthen skip the hook JMP SHORT rsint_8250_recv_rdy ENDIF rsint_8250_recv_loop: IF present_dv ; Put in the desqview wait hook as needed dv_cnt = dv_cnt + 1 dv_hook %dv_cnt CALL desqview rsint_8250_recv_rdy: ; Come here to start when in desqview mode ENDIF CMP BX,buffer_r_in[SI] ; See in anything in buffer JE rsint_8250_recv_loop ; Nope.. Keep looping ;--------------------------------------------------------------------------; ; Something is here.. Remove the character from the buffer ; ;--------------------------------------------------------------------------; MOV ES,buffer_r_a[SI] ; Get buffer segment MOV AH,ES:[BX] ; Get character from buffer.. Hide it in AH ;--------------------------------------------------------------------------; ; Bump the output pointer and handle the special case of where we wrap ; ; from one end of the buffer into the other ; ;--------------------------------------------------------------------------; INC BX ; Bump pointer CMP BX,buffer_size ; Have we wrapped the buffer? JL rsint_8250_recv_exit ; No.. All done SUB BX,BX ; Yes.. Reset pointer rsint_8250_recv_exit: MOV buffer_r_out[SI],BX ; Save pointer ;--------------------------------------------------------------------------; ; If we have hardware handshaking enabled, then see if we need to ; ; signal start. 1/16 is the limit we are using ; ;--------------------------------------------------------------------------; TEST options[SI],opt_hdwhs ; Hardware handshaking desired? JZ rsint_8250_r_nohshak ; Nope TEST flags[SI],flags_useoff ; Does user wants handshake off? JNZ rsint_8250_r_nohshak ; Yep... We dont touch it here MOV DX,BX ; Put pointer in work reg SUB DX,buffer_r_in[SI] ; Compute the delta JG rsint_8250_rpos ; Jump over if positive result ADD DX,buffer_size ; This will convert it back to positive rsint_8250_rpos: ; DX now is equal to bytes free! CMP DX,(buffer_size / 8) ; See if at least 1/8 is left JL rsint_8250_r_stop ; No... Leave stop on MOV DX,CX ; Get base address for chip ADD DX,mcr_8250 ; MOV AL,hon_8250 ; Raise DTR, RTS, and OUT2. OUT2 turns OUT DX,AL ; on interrupts. rsint_8250_r_stop: ; rsint_8250_r_nohshak: ; ;--------------------------------------------------------------------------; ; Remember we hid the receive character in AH... Put it where it belongs ; ; now ; ;--------------------------------------------------------------------------; MOV AL,AH ; ;--------------------------------------------------------------------------; ; Put out the last LSR we received with the exception of RDA. If we have ; ; no pending LSR, go get one ; ;--------------------------------------------------------------------------; SUB AH,AH ; Get the last LSR and XCHG AH,last_rs[SI] ; clear it too! OR AH,AH ; Is it non-existant? JNZ rsint_8250_rcv_nolsr; Nope MOV AH,AL ; Save the received character MOV DX,CX ; Get base address for chip ADD DX,lsr_8250 ; Now get a real LSR IN AL,DX ; XCHG AH,AL ; Put things back together rsint_8250_rcv_nolsr: ;--------------------------------------------------------------------------; ; Set the RDA bit based on buffer status ; ;--------------------------------------------------------------------------; AND AH,0FFH-lsr_8250_dr ; Remove data ready bit CMP BX,buffer_r_in[SI] ; Anything left in buffer? JE rsint_8250_rcv_go ; Nope so leave OR AH,lsr_8250_dr ; Turn on data ready rsint_8250_rcv_go: ; ;--------------------------------------------------------------------------; ; Done ; ;--------------------------------------------------------------------------; JMP rsint_exit ; and go leave ;==========================================================================; ; Status.. Return the MSR and the LSR ; ;==========================================================================; rsint_8250_status: MOV CX,baseaddr[SI] ; Get base address for chip ;--------------------------------------------------------------------------; ; Put out the current LSR plus the current Receive Data Available ; ; setting based on the buffer contents plus last_lsr ; ;--------------------------------------------------------------------------; MOV DX,CX ; Compute port address for the LSR ADD DX,lsr_8250 ; and then JMP $+2 ; IN AL,DX ; get it SUB AH,AH ; Get the last LSR and clear it too. XCHG AH,last_rs[SI] ; OR AL,AH ; OR it in AND AL,0FFH-lsr_8250_dr ; Remove data ready bit MOV BX,buffer_r_out[SI] ; Get buffer output pointer CMP BX,buffer_r_in[SI] ; Anything left in buffer? JE rsint_8250_status_nodr ; Nope so leave OR AL,lsr_8250_dr ; Turn on data ready rsint_8250_status_nodr: MOV AH,AL ; Save LSR ;--------------------------------------------------------------------------; ; Now lets get the MSR ; ;--------------------------------------------------------------------------; CALL rsint_8250_msr ; Get the MSR ;--------------------------------------------------------------------------; ; Save both the real LSR and the real MSR for later ; ;--------------------------------------------------------------------------; MOV DX,AX ; ;--------------------------------------------------------------------------; ; If we have transmit buffering active then we adjust the TBE and CTS ; ; bits based on current state of transmit buffers etc... ; ;--------------------------------------------------------------------------; TEST options[SI],opt_trbuf ; Transmit buffering turned on? JZ rsint_8250_status_notb; Nope... Skip this ;--------------------------------------------------------------------------; ; If the buffer is empty, use the TBE as set by the chip. In all ; ; other cases, TBE should be off since there is data in the buffer ; ;--------------------------------------------------------------------------; MOV BX,buffer_t_out[SI] ; Get buffer output pointer SUB BX,buffer_t_in[SI] ; Get buffer input pointer JG rsint_8250_status_tpos ; Jump over if positive result ADD BX,buffer_size ; This will convert it back to positive rsint_8250_status_tpos: ; BX now is equal to bytes left! CMP BX,buffer_size ; Max amount left in buffer? JE rsint_8250_status_empty; Yes.. Use the chip's THRE AND AH,0FFH-lsr_8250_thre ; Remove transmit holding register empty rsint_8250_status_empty: ;--------------------------------------------------------------------------; ; Hardware handshaking? If not, we can go ; ;--------------------------------------------------------------------------; TEST options[SI],opt_hdwhs ; Hardware handshaking desired? JZ rsint_8250_t_nostop ; Nope... we are done ;--------------------------------------------------------------------------; ; If the remote signals stop, so will we... ; ;--------------------------------------------------------------------------; TEST DL,msr_8250_cts ; See Clear to send (CTS) on from remote? JZ rsint_8250_status_tstop ; Nope..... Stop sending! ;--------------------------------------------------------------------------; ; Now we assume that we have a CTS on! .. ; ;--------------------------------------------------------------------------; OR AL,msr_8250_cts ; Set Clear to send (CTS) ; CTS is already on... ; becuz there is data in the buffer ;--------------------------------------------------------------------------; ; See if any room left in buffer. If so, we can go ; ;--------------------------------------------------------------------------; CMP BX,(buffer_size / 4) ; See if at least 1/4 is left JGE rsint_8250_t_nostop ; Yes.. No stop needed ;--------------------------------------------------------------------------; ; Signal to stop sending! ; ;--------------------------------------------------------------------------; rsint_8250_status_tstop: AND AH,0FFH-lsr_8250_thre ; Remove transmit holding register empty AND AL,0FFH-msr_8250_cts ; Remove Clear to send (CTS) rsint_8250_t_nostop: rsint_8250_status_notb: ;--------------------------------------------------------------------------; ; All done ; ;--------------------------------------------------------------------------; JMP rsint_exit ; All done ;==========================================================================; ; Subroutine to get the MSR... Why is special??? Because it could ; ; accidentally wipe out the pending modem state change interrupt ; ; Inputs : CX = port base address ; ; Outputs : AL = MSR ; ; Registers used: DX ; ;==========================================================================; rsint_8250_msr: MOV DX,CX ; Compute port address for the MSR ADD DX,msr_8250 ; and then IN AL,DX ; get it TEST AL,msr_8250_dcts ; Delta CTS? JZ SHORT rsint_8250_msr_exit ; Nope..... leave... TEST AL,msr_8250_cts ; CTS on? JZ SHORT rsint_8250_msr_exit ; Nope..... leave... ; We have accidentally eaten an interrupt intended for the handler... ; Now create a pseudo interrupt! MOV DL,hiv[SI] ; Get the hardware interrupt vector address MOV rsint_8250_msr_int,DL ; Put it where we need it JMP $+2 ; Clean out prefetch stack INT 00H ; Interrupt! ORG $-1 rsint_8250_msr_int DB ? ; Place to put interrupt number ; We are going to exit here with interrupt ; masked since we will exit in a very very short ; time rsint_8250_msr_exit: RET ; Return to caller ;==========================================================================; ; Extended service routines are below (if any) ; ;==========================================================================; IF present_8250x INCLUDE 8250svcx.asm ; ENDIF