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Assembly Source File | 1992-02-10 | 25KB | 992 lines

version equ 6 include defs.asm ;Ported from Phil Karn's asy.c and slip.c, a C-language driver for the IBM-PC ;8250 by Russell Nelson. Any bugs are due to Russell Nelson. ;16550 support ruthlessly stolen from Phil Karn's 8250.c. ; Bugs by Denis DeLaRoca ; Stopped failures from lost transmit interrupts (by eliminating the ints ; altogether). Remove unneeded transmitter buffer. ; Version 6 by Joe Doupnik, jrd@cc.usu.edu, Utah State University, Dec 1991. ; Copyright, 1988, 1991, Russell Nelson ; This program is free software; you can redistribute it and/or modify ; it under the terms of the GNU General Public License as published by ; the Free Software Foundation, version 1. ; ; This program is distributed in the hope that it will be useful, ; but WITHOUT ANY WARRANTY; without even the implied warranty of ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ; GNU General Public License for more details. ; ; You should have received a copy of the GNU General Public License ; along with this program; if not, write to the Free Software ; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. code segment word public assume cs:code, ds:code ;8250 definitions ;Control/status register offsets from base address THR equ 0 ;Transmitter holding register RBR equ 0 ;Receiver buffer register DLL equ 0 ;Divisor latch LSB DLM equ 1 ;Divisor latch MSB IER equ 1 ;Interrupt enable register IIR equ 2 ;Interrupt ident register FCR equ 2 ;16550 FIFO control register LCR equ 3 ;Line control register MCR equ 4 ;Modem control register LSR equ 5 ;Line status register MSR equ 6 ;Modem status register ;8250 Line Control Register LCR_5BITS equ 0 ;5 bit words LCR_6BITS equ 1 ;6 bit words LCR_7BITS equ 2 ;7 bit words LCR_8BITS equ 3 ;8 bit words LCR_NSB equ 4 ;Number of stop bits LCR_PEN equ 8 ;Parity enable LCR_EPS equ 10h ;Even parity select LCR_SP equ 20h ;Stick parity LCR_SB equ 40h ;Set break LCR_DLAB equ 80h ;Divisor Latch Access Bit ;16550 FIFO control register values FIFO_ENABLE equ 001h ;Enable TX and RX fifo FIFO_CLR_RX equ 002h ;Clear RX fifo FIFO_CLR_TX equ 004h ;Clear TX fifo FIFO_START_DMA equ 008h ;Enable TXRDY/RXRDY pin DMA handshake FIFO_SIZE_1 equ 000h ;RX fifo trigger levels FIFO_SIZE_4 equ 040h FIFO_SIZE_8 equ 080h FIFO_SIZE_14 equ 0c0h FIFO_SIZE_MASK equ 0c0h FIFO_TRIGGER_LEVEL equ FIFO_SIZE_4 FIFO_SETUP equ FIFO_ENABLE+FIFO_CLR_RX+FIFO_CLR_TX+FIFO_TRIGGER_LEVEL OUTPUT_FIFO_SIZE equ 16 ;8250 Line Status Register LSR_DR equ 1 ;Data ready LSR_OE equ 2 ;Overrun error LSR_PE equ 4 ;Parity error LSR_FE equ 8 ;Framing error LSR_BI equ 10h ;Break interrupt LSR_THRE equ 20h ;Transmitter line holding register empty LSR_TSRE equ 40h ;Transmitter shift register empty ;8250 Interrupt Identification Register IIR_IP equ 1 ;0 if interrupt pending IIR_ID equ 6 ;Mask for interrupt ID IIR_RLS equ 6 ;Receiver Line Status interrupt IIR_RDA equ 4 ;Receiver data available interrupt IIR_THRE equ 2 ;Transmitter holding register empty int IIR_MSTAT equ 0 ;Modem status interrupt IIR_FIFO_TIMEOUT equ 008h ;FIFO timeout interrupt pending - 16550 only IIR_FIFO_ENABLED equ 080h ;FIFO enabled (FCR0 = 1) - 16550 only ;8250 interrupt enable register bits IER_DAV equ 1 ;Data available interrupt IER_TxE equ 2 ;Tx buffer empty interrupt IER_RLS equ 4 ;Receive line status interrupt IER_MS equ 8 ;Modem status interrupt ;8250 Modem control register MCR_DTR equ 1 ;Data Terminal Ready MCR_RTS equ 2 ;Request to Send MCR_OUT1 equ 4 ;Out 1 (not used) MCR_OUT2 equ 8 ;Master interrupt enable (actually OUT 2) MCR_LOOP equ 10h ;Loopback test mode ;8250 Modem Status Register MSR_DCTS equ 1 ;Delta Clear-to-Send MSR_DDSR equ 2 ;Delta Data Set Ready MSR_TERI equ 4 ;Trailing edge ring indicator MSR_DRLSD equ 8 ;Delta Rx Line Signal Detect MSR_CTS equ 10h ;Clear to send MSR_DSR equ 20h ;Data set ready MSR_RI equ 40h ;Ring indicator MSR_RLSD equ 80h ;Received line signal detect ;Slip Definitions FR_END equ 0c0h ;Frame End FR_ESC equ 0dbh ;Frame Escape T_FR_END equ 0dch ;Transposed frame end T_FR_ESC equ 0ddh ;Transposed frame escape public int_no int_no db 4,0,0,0 ; interrupt number. io_addr dw 03f8h,0 ; I/O address for COM1 baud_rate dw 12c0h,0 ; support baud higher than 65535 baudclk label word dd 115200 ; 1.8432 Mhz / 16 hardware_switch db 0 ; if zero, don't use hw handshaking is_16550 db 0 ; 0=no, 1=yes (try using fifo) public driver_class, driver_type, driver_name public driver_function, parameter_list driver_class db 6,0,0,0 ;from the packet spec driver_type db 0,0,0,0 ;from the packet spec driver_name db 'SLIP8250',0 ;name of the driver. driver_function db 2 parameter_list label byte db 1 ;major rev of packet driver db 9 ;minor rev of packet driver db 14 ;length of parameter list db EADDR_LEN ;length of MAC-layer address dw GIANT ;MTU, including MAC headers dw MAX_MULTICAST * EADDR_LEN ;buffer size of multicast addrs dw 0 ;(# of back-to-back MTU rcvs) - 1 dw 0 ;(# of successive xmits) - 1 int_num dw 0 ;Interrupt # to hook for post-EOI ;processing, 0 == none, ifdef debug public recv_buf_size, recv_buf, recv_buf_end, recv_buf_head public recv_buf_tail, recv_pkt_ready endif recv_buf_size dw 3000,0 ;receive buffer size recv_buf dw ? ;->receive buffer recv_buf_end dw ? ;->after end of buffer recv_buf_head dw ? ;->next character to get recv_buf_tail dw ? ;->next character to store recv_pkt_ready dw 0 ; flag indicating a packet is ready IP_TYPE DW 0800H ifdef debug public packet_sem, xmit_time endif packet_sem dw 0 ; semaphore for packets received asyrxint_cnt dw 0 ; loop counter in asyrxint xmit_time dw 0 ; loop timer for asyrxint public rcv_modes rcv_modes dw 4 ;number of receive modes in our table dw 0,0,0,rcv_mode_3 public as_send_pkt ; The Asynchronous Transmit Packet routine. ; Enter with es:di -> i/o control block, ds:si -> packet, cx = packet length, ; interrupts possibly enabled. ; Exit with nc if ok, or else cy if error, dh set to error number. ; es:di and interrupt enable flag preserved on exit. as_send_pkt: ret public drop_pkt ; Drop a packet from the queue. ; Enter with es:di -> iocb. drop_pkt: assume ds:nothing ret public xmit ; Process a transmit interrupt with the least possible latency to achieve ; back-to-back packet transmissions. ; May only use ax and dx. xmit: assume ds:nothing ret public send_pkt ; ; mod 7/25/89 John Grover ; - operates with interrupts on. Xmits one byte per interrupt ; - only turns transmitter buffer empty interrupt off when ; - all bytes of all packets are transmitted. send_pkt: ;enter with es:di->upcall routine, (0:0) if no upcall is desired. ; (only if the high-performance bit is set in driver_function) ;enter with ds:si -> packet, cx = packet length. ;exit with nc if ok, or else cy if error, dh set to error number. ;called from telnet layer via software interrupt ; We just send each byte in turn. No UART interrupts are needed nor wanted. ; In fact the overdone receiver material omits to note that xmtr interrupts ; can be lost while processing rcvr ones. Small benefits are no stalled ; programs, no transmitter buffer, no problems at 19200 b/s. Joe Doupnik assume ds:nothing, es:nothing sti ; enable interrupts cld mov al,FR_END ; Flush out any line garbage call send_char jc send_pkt_end ; c = failure to send ;Copy input to output, escaping special characters send_pkt_1: lodsb cmp al,FR_ESC ; escape FR_ESC with FR_ESC and T_FR_ESC jne send_pkt_2 mov al,FR_ESC call send_char jc send_pkt_end mov al,T_FR_ESC jmp short send_pkt_3 send_pkt_2: cmp al,FR_END ; escape FR_END with FR_ESC and T_FR_END jne send_pkt_3 mov al,FR_ESC call send_char jc send_pkt_end mov al,T_FR_END send_pkt_3: call send_char jc send_pkt_end loop send_pkt_1 ; do cx user characters mov al,FR_END ; terminate it with a FR_END call send_char jc send_pkt_end clc send_pkt_end: ret ; mod 7/25/89 John Grover ; redone by Joe Doupnik, Dec 1991 assume ds:nothing, es:nothing send_char: ; send the character in al push dx push cx xchg ah,al ; put data char into ah xor cx,cx ; 64K retry counter sendch1:mov dx,io_addr ; 03f8h base address add dx,LSR ; 03fdh get port status in al,dx test al,LSR_THRE ; Transmitter (THRE) ready? jnz sendch2 ; nz = yes jmp $+2 ; use time, prevent overdriving UART jmp $+2 loop sendch1 stc ; carry set for failure jmp short sendch3 ; timeout sendch2:xchg al,ah ; now send it mov dx,io_addr ; 03f8h, use a little time jmp $+2 out dx,al ; send the byte clc ; status of success sendch3:pop cx pop dx ret public get_address get_address: ;get the address of the interface. ;enter with es:di -> place to get the address, cx = size of address buffer. ;exit with nc, cx = actual size of address, or cy if buffer not big enough. assume ds:code xor cx,cx clc ret public set_address set_address: ;set the address of the interface. ;enter with es:di -> place to get the address, cx = size of address buffer. ;exit with nc, cx = actual size of address, or cy if buffer not big enough. assume ds:nothing clc ret rcv_mode_3: ;receive mode 3 is the only one we support, so we don't have to do anything. ret public set_multicast_list set_multicast_list: ;enter with ds:si ->list of multicast addresses, cx = number of addresses. ;return nc if we set all of them, or cy,dh=error if we didn't. mov dh,NO_MULTICAST stc ret public get_multicast_list get_multicast_list: ;return with nc, es:di ->list of multicast addresses, cx = number of bytes. ;return cy, NO_ERROR if we don't remember all of the addresses ourselves. ;return cy, NO_MULTICAST if we don't implement multicast. mov dh,NO_MULTICAST stc ret public terminate terminate: ret public reset_interface reset_interface: ;reset the interface. assume ds:code ret ;called when we want to determine what to do with a received packet. ;enter with cx = packet length, es:di -> packet type, dl = packet class. extrn recv_find: near ;called after we have copied the packet into the buffer. ;enter with ds:si ->the packet, cx = length of the packet. extrn recv_copy: near extrn count_in_err: near extrn count_out_err: near public recv ; ; mod 7/25/89 John Grover ; ; - added code to check modem status change interrupt. If CTS is ; - low turn off transmitter buffer empty interrupt. If CTS is ; - high turn it on. recv: ;called from the recv isr. All registers have been saved, and ds=cs. ;Upon exit, the interrupt will be acknowledged. assume ds:code recv_2: loadport setport IIR in al,dx ;any interrupts at all? test al,IIR_IP jne recv_1 ;no. and al,IIR_ID cmp al,IIR_RDA ;Receiver interrupt jne recv_3 call asyrxint jmp recv_2 recv_3: recv_5: ;process IIR_MSTAT here. ; If CTS and packet ready then ; enable the transmit buffer empty interrupt ; else ; disable the transmit buffer empty interrupt ; cmp al, IIR_MSTAT jne recv_1 setport MSR ; make sure of CTS status in al, dx ; test al, MSR_CTS ; is CTS bit set ; jz recv_5_1 ; no - disable xmit buffer empty int jmp recv_2 recv_5_1: jmp recv_2 ;process IIR_RLS here recv_1: ret ;Process 8250 receiver interrupts ; ; mod 7/25/89 John Grover ; - this branches off when bps < 9600. See asyrxint_a. ; - Above 9600 bps we go into a loop to process a packet at ; - a time. If not data ready for a certain amount of time, ; - the process exits and waits for the next byte. This certain ; - amount of time to wait depends on the bps and CPU processor speed ; - and is determined in the initialization of the driver. ; - Upon receiving the FR_END character for the first frame in the ; - buffer a semaphore is set which tells recv_frame to run. asyrxint: push ds ; get set up for the routine pop es xor bx, bx cmp baud_rate, 9600 ; below 9600 we're strictly jbe asyrxint_a ; interrupt driven mov bx, xmit_time asyrxint_a: mov di,recv_buf_tail xor bp, bp ; set flag to indicate 1st char ; processed mov si, packet_sem ; optimization loadport mov ah, LSR_DR asyrxint_again: xor cx, cx ; initialize counter setport LSR asyrxint_in: in al,dx ; check for data ready test al,LSR_DR jnz asyrxint_gotit ; yes - break out of loop inc cx ; no - increase loop counter cmp cx, bx ; timeout? jae asyrxint_exit ; yes - leave jmp asyrxint_in ; no - keep looping asyrxint_gotit: setport RBR in al,dx ;Process incoming data; ; If buffer is full, we have no choice but ; to drop the character cmp di,recv_buf_head ; check for buffer collision jne asyrxint_ok ; none - continue or si, si ; maybe - if there are packets jnz asyrxint_exit ; yes exit asyrxint_ok: stosb cmp di,recv_buf_end ; did we hit the end of the buffer? jne asyrxint_3 ; no. mov di,recv_buf ; yes - wrap around. asyrxint_3: cmp al,FR_END ; might this be the end of a frame? jne asyrxint_reset ; no - reset flag and loop inc si ; yes - indicate packet ready cmp si, 1 ; determine if semaphore is <> 1 jne asyrxint_chk_flg ; yes - recv_frame must be active inc recv_pkt_ready ; no - set flag to start recv_frame asyrxint_chk_flg: cmp bp, 0 ; was this the first char? jne asyrxint_1 ; no - exit handler asyrxint_reset: inc bp ; set 1st character flag jmp asyrxint_again ; get another character asyrxint_exit: asyrxint_1: mov recv_buf_tail,di mov packet_sem, si ret ; -------------------------------------------------------------- ; ; recv_exiting ; public recv_exiting recv_exiting: cmp recv_pkt_ready, 1 ; is a packet ready? jne recv_isr_exit ; no - skip to end push ax push bx push cx push dx push ds push es push bp push di push si push cs ; point ds properly pop ds mov recv_pkt_ready, 0 ; reset flag sti ; enable interrupts call recv_frame cli pop si pop di pop bp pop es pop ds pop dx pop cx pop bx pop ax recv_isr_exit: ret ; -------------------------------------------------------------- ; ; recv_frame ; ; mod 7/25/89 John Grover ; ; - recv_frame now operates with interrupts on. It is triggered ; - by the recv_pkt_ready flag and continues until all bytes ; - in all packets in the buffer have been transmitted to the upper ; - layer. ; ifdef debug public recv_frame endif recv_frame: cmp packet_sem, 0 ; should we do this? jz recv_frame_end ; no - exit mov si,recv_buf_head ;process characters. xor cx,cx ;count up the size here. recv_frame_1: call recv_char ;get a char. je recv_frame_2 ;go if no more chars. cmp al,FR_ESC ;an escape? je recv_frame_1 ;yes - don't count this char. inc cx ;no - count this one. jmp recv_frame_1 recv_frame_2: jcxz recv_frame_3 ;count zero? yes - free the frame ;we don't need to set the type because none are defined for SLIP. push si ;save si in case we reject it. push bx MOV DI,CS MOV ES,DI mov di,0 mov dl,cs:driver_class call recv_find ;look up our type. pop bx pop si mov ax,es ;is this pointer null? or ax,di je recv_frame_3 ;yes - just free the frame. push cx push es ;remember where the buffer pointer is push di mov si,recv_buf_head ;process characters. recv_frame_4: call recv_char je recv_frame_6 ;yes - we're all done. cmp al,FR_ESC ;an escape? jne recv_frame_5 ;no - just store it. call recv_char ;get the next character. je recv_frame_6 cmp al,T_FR_ESC mov al,FR_ESC ;assume T_FR_ESC je recv_frame_5 ;yup, that's it - store FR_ESC mov al,FR_END ;nope, store FR_END recv_frame_5: stosb ;store the byte. jmp recv_frame_4 recv_frame_6: mov recv_buf_head,si ;we're skipped to the end. pop si ;now give the frame to the client. pop ds pop cx assume ds:nothing call recv_copy push cs pop ds assume ds:code jmp recv_frame_end recv_frame_3: mov recv_buf_head,si ;remember the new starting point. recv_frame_end: dec packet_sem cmp packet_sem, 0 ; are there more packets ready? ja recv_frame ; yes - execute again ret ; -------------------------------------------------------------- ; ; recv_char ; ; mod 7/25/89 John Grover ; - Now uses buffer pointers to determine if there are ; - characters left. ; recv_char: ;enter with si -> receive buffer, bx = receive count. Wrap around if needed. ;return with nz, al = next char. Return zr if there are no more chars in ; this frame. ; lodsb cmp si,recv_buf_end jb recv_char_1 mov si,recv_buf recv_char_1: mov bx, recv_buf_tail cmp si, bx je recv_char_2 cmp al,FR_END recv_char_2: ret ;Set bit(s) in I/O port setbit: ;enter with dx = port, ah = bit to set. in al,dx or al,ah out dx,al ret ;Clear bit(s) in I/O port clrbit: ;enter with dx = port, ah = bit to set. in al,dx not al ;perform an and-not using DeMorgan's. or al,ah not al out dx,al ret ;any code after this will not be kept after initialization. end_resident label byte public usage_msg usage_msg db "usage: SLIP8250 [-n] [-d] [-w] packet_int_no " db "[-h] [driver_class] [int_no]",CR,LF db " [io_addr] [baud_rate]",CR,LF db " [recv_buf_size]",CR,LF db " -h enables hardware handshaking",CR,LF db " The driver_class should be SLIP, KISS, AX.25," db " or a number.",CR,LF,'$' public copyright_msg copyright_msg db "Packet driver for SLIP8250, version ",'0'+majver db ".",'0'+version,CR,LF db "Portions Copyright 1988 Phil Karn",CR,LF db "Portions Copyright 1991 Joe Doupnik",cr,lf,'$' approximate_msg db "Warning: This baud rate can only be approximated" db "using the 8250",CR,LF db "because it is not an even divisor of 115200" db cr,lf,'$' is_16550_msg db "16550 Uart detected, FIFO will be used",CR,LF,'$' class_name_ptr dw ? class_name db "Interface class ",'$' kiss_name db "KISS",CR,LF,'$' ax25_name db "AX.25",CR,LF,'$' slip_name db "SLIP",CR,LF,'$' int_no_name db "Interrupt number ",'$' io_addr_name db "I/O port ",'$' baud_rate_name db "Baud rate ",'$' recv_buf_name db "Receive buffer size ",'$' unusual_com1 db "That's unusual! Com1 (0x3f8) usually uses IRQ 4!" db CR,LF,'$' unusual_com2 db "That's unusual! Com2 (0x2f8) usually uses IRQ 3!" db CR,LF,'$' extrn set_recv_isr: near ;enter with si -> argument string, di -> word to store. ;if there is no number, don't change the number. extrn get_number: near ;enter with dx -> name of word, di -> dword to print. extrn print_number: near ;enter with si -> argument string. ;skip spaces and tabs. Exit with si -> first non-blank char. extrn skip_blanks: near public parse_args parse_args: ;exit with nc if all went well, cy otherwise. call skip_blanks cmp al,'-' ;did they specify a switch? jne not_switch cmp byte ptr [si+1],'h' ;did they specify '-h'? je got_hardware_switch stc ;no, must be an error. ret got_hardware_switch: mov hardware_switch,1 add si,2 ;skip past the switch's characters. jmp parse_args ;go parse more arguments. not_switch: or al,20h ; to lower case (assuming letter) cmp al,'k' jne parse_args_2 mov driver_class,10 ;KISS, from packet spec mov dx,offset kiss_name jmp short parse_args_1 parse_args_2: cmp al,'s' jne parse_args_3 mov driver_class,6 ;SLIP, from packet spec mov dx,offset slip_name jmp short parse_args_1 parse_args_3: cmp al,'a' jne parse_args_4 mov driver_class,9 ;AX.25, from packet spec. mov dx,offset ax25_name jmp short parse_args_1 parse_args_4: mov di,offset driver_class mov bx,offset class_name call get_number mov class_name_ptr,0 jmp short parse_args_6 parse_args_1: mov class_name_ptr,dx parse_args_5: mov al,[si] ;skip to the next blank or CR. cmp al,' ' je parse_args_6 cmp al,CR je parse_args_6 inc si ;skip the character. jmp parse_args_5 parse_args_6: mov di,offset int_no call get_number mov di,offset io_addr call get_number mov di,offset baud_rate call get_number mov di,offset recv_buf_size call get_number clc ret ; -------------------------------------------------------------- ; ; etopen ; ; mod 7/25/89 John Grover ; - Contains a loop to determine a pseudo timeout for asyrxint. ; - The value is determined by transmitting characters in a ; - loop whose clock cycles are nearly the same as the "sister" ; - loop in asyrxint. The per character, maximum time used ; - basis which is then multiplied by a factor to achieve a timeout ; - value for the particular bps and CPU speed of the host. public etopen etopen: pushf cli ; ; mod 3/16/90 Denis DeLaRoca ; - determine if 16550 uart is present ; - if so initialize fifo buffering ; loadport setport FCR mov al,FIFO_ENABLE out dx,al ;outportb(base+FCR,(char) FIFO_ENABLE) setport IIR in al,dx ;inportb(base+IIR) and al,IIR_FIFO_ENABLED ; & IIR_FIFO_ENABLED cmp al,IIR_FIFO_ENABLED ;both bits must be on NEW, 11/20/90 jnz not_16550 ;nope, we don't have 16550 chip mov is_16550,1 ;yes, note fact mov al,FIFO_SETUP ;and setup FIFO setport FCR out dx,al ;outportb(base+FCR,(char) FIFO_SETUP) mov dx,offset is_16550_msg mov ah,9 int 21h ;let user know about 16550 not_16550: loadport ;Purge the receive data buffer setport RBR in al,dx ;Set line control register: 8 bits, no parity mov al,LCR_8BITS setport LCR out dx,al ;Turn on receive interrupt enable in 8250, leave transmit ; and modem status interrupts turned off for now mov al,IER_DAV setport IER out dx,al ;Set modem control register: assert DTR, RTS, turn on 8250 ; master interrupt enable (connected to OUT2) mov al,MCR_DTR or MCR_RTS or MCR_OUT2 setport MCR out dx,al ;compute the divisor given the baud rate. mov dx,baudclk+2 mov ax,baudclk mov bx,0 asy_speed_1: inc bx sub ax,baud_rate sbb dx,baud_rate+2 jnc asy_speed_1 dec bx add ax,baud_rate adc dx,baud_rate+2 or ax,dx je asy_speed_2 mov dx,offset approximate_msg mov ah,9 int 21h asy_speed_2: loadport ;Purge the receive data buffer setport RBR in al,dx mov ah,LCR_DLAB ;Turn on divisor latch access bit setport LCR call setbit mov al,bl ;Load the two bytes of the divisor. setport DLL out dx,al mov al,bh setport DLM out dx,al mov ah,LCR_DLAB ;Turn off divisor latch access bit setport LCR call clrbit call set_recv_isr ;Set interrupt vector to SIO handler ;set up the various pointers. mov dx,offset end_resident mov recv_buf,dx mov recv_buf_head,dx mov recv_buf_tail,dx add dx,recv_buf_size mov recv_buf_end,dx push dx ;save the ending address. ; the following code attempts to determine a pseudo timeout ; value to use in the loop that waits for an incoming character ; in asyrxint. The value returned in xmit_time is the number of ; loops processed between characters - therefore the loop used below ; is and should remain similar to the loop used in asyrxint. xor ax, ax ; we'll send a 0 mov ah, LSR_THRE mov cx, 10h ; take the highest of 16 runs xor si, si ; will hold highest value xmit_time_start: xor di, di ; initialize counter loadport setport THR ; xmit a character out dx, al setport LSR ; set up to check for an empty buffer ; next is the loop actually being timed xmit_time_top: in al, dx test al, ah jnz xmit_time_done inc di cmp cx, cx ; these next few instructions do nothing jmp xmit_time_1 ; except maintain similarity with the ; "sister" loop in asyrxint xmit_time_1: jmp xmit_time_top xmit_time_done: ; end of timed loop cmp si, di ; compare highest value with new value ja xmit_time_end ; no bigger - just loop mov si, di ; bigger - save it xmit_time_end: loop xmit_time_start ; bottom of outer loop shl si, 1 ; we'll wait 8 characters worth shl si, 1 shl si, 1 mov xmit_time, si ; retain largest value ; end of pseudo timer determination mov al, int_no ; Get board's interrupt vector add al, 8 cmp al, 8+8 ; Is it a slave 8259 interrupt? jb set_int_num ; No. add al, 70h - 8 - 8 ; Map it to the real interrupt. set_int_num: xor ah, ah ; Clear high byte mov int_num, ax ; Set parameter_list int num. pop dx ;return the ending address. popf clc ;indicate no errors. ret public print_parameters print_parameters: ;echo our command-line parameters cmp class_name_ptr,0 je echo_args_1 mov dx,offset class_name mov ah,9 int 21h mov dx,class_name_ptr mov ah,9 int 21h jmp short echo_args_2 echo_args_1: mov di,offset driver_class mov dx,offset class_name call print_number echo_args_2: mov di,offset int_no mov dx,offset int_no_name call print_number mov di,offset io_addr mov dx,offset io_addr_name call print_number cmp io_addr,03f8h ;is this com1? jne ia_com2 mov dx,offset unusual_com1 cmp int_no,4 ;com1 usually uses IRQ 4. jne ia_unusual jmp short ia_usual ia_com2: cmp io_addr,02f8h ;is this com2? jne ia_usual ;no. mov dx,offset unusual_com2 cmp int_no,3 ;com2 usually uses IRQ 3. je ia_usual ia_unusual: mov ah,9 int 21h ia_usual: mov di,offset baud_rate mov dx,offset baud_rate_name call print_number mov di,offset recv_buf_size mov dx,offset recv_buf_name call print_number ret code ends end