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Assembly Source File | 1988-10-20 | 14.7 KB | 619 lines

version equ 3 include defs.asm ;SEE ENCLOSED COPYRIGHT MESSAGE ;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. ;/* PC/FTP Packet Driver source, conforming to version 1.05 of the spec ;* Portions (C) Copyright 1988 Phil Karn ;* ;* Permission is granted to any individual or institution to use, copy, ;* modify, or redistribute this software and its documentation provided ;* this notice and the copyright notices are retained. This software may ;* not be distributed for profit, either in original form or in derivative ;* works. Phil Karn makes no representations about the suitability ;* of this software for any purpose. PHIL KARN GIVES NO WARRANTY, ;* EITHER EXPRESS OR IMPLIED, FOR THE PROGRAM AND/OR DOCUMENTATION ;* PROVIDED, INCLUDING, WITHOUT LIMITATION, WARRANTY OF MERCHANTABILITY ;* AND WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE. ;*/ code segment byte 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 Line Control Register FCR_RCVR equ 002h ;Reset Receive FIFO FCR_XMIT equ 004h ;Reset Transmit FIFO FCR_1 equ 001h ;One byte FIFO FCR_4 equ 041h ;Four byte FIFO FCR_8 equ 081h ;Eight byte FIFO FCR_14 equ 0c1h ;Fourteen byte FIFO ;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 ;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 3,0,0,0 ; interrupt number. io_addr dw 03f8h,0 ; I/O address for COM1. baud_rate dw 0,0 ; We support baud rates higher than 65535. baudclk label word dd 115200 ;1.8432 Mhz / 16 public driver_class, driver_type, driver_name driver_class db 6 ;from the packet spec driver_type db 0 ;from the packet spec driver_name db 'SLIP8250',0 ;name of the driver. recv_buf_size dw 3000 ;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_cnt dw ? ;number of characters in the queue. send_buf_size dw 3000 ;send buffer size send_buf dw ? ;->send buffer send_buf_end dw ? ;->after end of buffer send_buf_head dw ? ;->next character to get send_buf_tail dw ? ;->next character to store send_cnt dw ? ;number of characters in the queue. public send_pkt send_pkt: ;enter with ds:si -> packet, cx = packet length. ;exit with nc if ok, or else cy if error, dh set to error number. assume ds:nothing push cs pop es mov di,send_buf_tail mov bx,send_cnt mov al,FR_END ;Flush out any line garbage call send_char ;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 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 mov al,T_FR_END send_pkt_3: call send_char loop send_pkt_1 mov al,FR_END ;terminate it with a FR_END call send_char mov send_buf_tail,di mov send_cnt,bx ;Enable transmitter buffer empty interrupt. mov ah,IER_TxE loadport setport IER call setbit ret send_char: ;stuff the character in al into the transmit buffer, but only if there ;is enough room, otherwise ignore the char. assume ds:nothing mov dx,send_cnt ;too many chars? cmp dx,send_buf_size je send_char_1 ;yes. inc bx ;count up a char. stosb ;store the char. cmp di,send_buf_end ;do we need to wrap around? jne send_char_1 ;no. mov di,send_buf ;yes - reload with beginning. send_char_1: 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 clc 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. 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 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: cmp al,IIR_THRE ;Transmit interrupt jne recv_4 call asytxint jmp recv_2 recv_4: ;process IIR_RLS here. recv_1: ret ;Process 8250 receiver interrupts asyrxint: asyrxint_2: loadport setport LSR in al,dx test al,LSR_DR je asyrxint_1 setport RBR in al,dx ;Process incoming data; ; If buffer is full, we have no choice but ; to drop the character mov cx,recv_cnt cmp cx,recv_buf_size je asyrxint_1 push ds pop es mov di,recv_buf_tail 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: mov recv_buf_tail,di inc recv_cnt cmp al,FR_END ;might this be the end of a frame? jne asyrxint_4 ;no. call recv_frame asyrxint_4: jmp asyrxint_2 asyrxint_1: ret recv_frame: mov si,recv_buf_head ;process characters. mov bx,recv_cnt mov cx,0 ;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 - just 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,0 ;but we avoid any segment end bullshit. 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. mov bx,recv_cnt 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. mov recv_cnt,bx pop si ;now give the frame to the client. pop ds pop cx assume ds:nothing call recv_copy assume ds:code ret recv_frame_3: mov recv_buf_head,si ;remember the new starting point. mov recv_cnt,bx ret 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: dec bx je recv_char_2 cmp al,FR_END recv_char_2: ret ;Handle 8250 transmitter interrupts asytxint: mov si,send_buf_head asytxint_2: loadport ;can we load another character? setport LSR in al,dx test al,LSR_THRE je asytxint_1 ;no. lodsb ;fill up the transmit buffer. cmp si,send_buf_end ;have we hit the end yet? jb asytxint_3 ;no. mov si,send_buf asytxint_3: setport THR out dx,al dec send_cnt ;keep sending until we run out. jne asytxint_2 ;No more characters to transmit -- disable transmit interrupts. setport IER ;Disable transmit interrupts mov ah,IER_TxE call clrbit ;Call completion interrupt here asytxint_1: mov send_buf_head,si 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 packet_int_no [driver_class] [int_no] [io_addr] [baud_rate]",CR,LF," [send_buf_size] [recv_buf_size]",CR,LF db " The driver_class should be SLIP, KISS, AX.25, or a number.",CR,LF,'$' public copyright_msg copyright_msg db "Packet driver for SLIP8250, version ",'0'+version,CR,LF db "Portions Copyright 1988 Phil Karn",CR,LF,'$' approximate_msg db "Warning: This baud rate can only be approximated using the 8250",CR,LF db "because it is not an even divisor of 115200",CR,LF,'$' class_name db "Interface class ",'$' 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 ",'$' baud_rate_name db "Baud rate ",'$' send_buf_name db "Send buffer size ",'$' recv_buf_name db "Receive buffer size ",'$' 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 si -> argument string. ;skip spaces and tabs. Exit with si -> first non-blank char. extrn skip_blanks: near public parse_args parse_args: call skip_blanks mov al,[si] ;now classify the argument. or al,20h ;convert 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 jmp short parse_args_6 parse_args_1: push dx mov dx,offset class_name mov ah,9 int 21h pop dx mov ah,9 int 21h 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 mov bx,offset int_no_name call get_number mov di,offset io_addr mov bx,offset io_addr_name call get_number mov di,offset baud_rate mov bx,offset baud_rate_name call get_number mov di,offset send_buf_size mov bx,offset send_buf_name call get_number mov di,offset recv_buf_size mov bx,offset recv_buf_name call get_number ret public etopen etopen: pushf cli loadport ;Purge the receive data buffer setport RBR in al,dx ;Enable FIFO, set FIFO trigger level to 8 mov al,FCR_8 setport FCR out dx,al ;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 send_buf,dx mov send_buf_head,dx mov send_buf_tail,dx add dx,send_buf_size mov send_buf_end,dx mov recv_buf,dx mov recv_buf_head,dx mov recv_buf_tail,dx add dx,recv_buf_size mov recv_buf_end,dx popf clc ;indicate no errors. ret code ends end