C/C++ Users Group Library 1996 July

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Assembly Source File | 1990-05-14 | 5.9 KB | 315 lines

title async.asm page 60,132 ;============================================================================== ; ; The Microcom MNP Library ; (Microsoft C Version) ; ;------------------------------------------------------------------------------ ; ; ASYNC - Async I/O interrupt handler management routines ; (set/clear interrupt routines also here) ; ;--------------------------------------------------------------------------- ; ; Modification History: ; ; 4/1/87 - Compuserve V1.0 ; ;============================================================================== ; ic_imr equ 21h ;i/o address of interrupt mask reg ; Public declarations public _drvr_ins public _drvr_rem public _clr_int public _set_int ; public _port_add extrn _port_add:word ; public _hard_int ; public _chan_no extrn _chan_no:word ; Externals extrn _ascode:near ; Data Segment _data segment word public 'DATA' _data ends dgroup group _data _data segment word public 'DATA' assume ds:dgroup ; public _linestat extrn _linestat:byte ; public _iir_add extrn _iir_add:word public _async extrn _baudrate:byte _hard_int db 0 ;hardware interrupt # ;_port_add dw 0 ;base address of sio hardware ;_chan_no dw 0 ;channel # being used ; db 100 dup(?) stack equ $ drvr_active db 0 ;_linestat db ? old_vct dw ? dw ? ;_iir_add dw ? ic_imr_sav db ? ; _data ends _text segment byte public 'CODE' assume cs:_text,ds:dgroup extrn cdsg:word page ;PUBLIC--------------------------------------------------------------------- ; ; _drvr_ins - install async interrupt handler and set up async card ; ;--------------------------------------------------------------------------- _drvr_ins proc near push bp mov bp,sp push bx push dx push es cmp drvr_active,1 ;already installed ? jne doit ;no, go install jmp done doit: mov ax,_chan_no ; get channel number mov _port_add,03f8h ; assume port 1 mov _hard_int,0ch cmp al,0 ; is it 1? je do1 ; yes-go on mov _port_add,02f8h ; no-setup for port 2 dec _hard_int do1: in al,ic_imr jmp short $+2 mov ic_imr_sav,al mov al,0ffh out ic_imr,al mov ah,35h ;ask for current vector contents mov al,_hard_int ;specify which vector int 21h mov old_vct,bx ;save current vector values mov old_vct+2,es mov dx,offset _async mov ah,25h ;install new vector values mov al,_hard_int push ds ;save current ds push cs pop ds ;ds = cs int 21h pop ds ;restore ds mov ax,_port_add inc ax inc ax mov _iir_add,ax ; mov drvr_active,1 ; ; initialize rs-232 driver to character format and baud rate ; mov al,_baudrate mov cl,5 ;adjust for format shl al,cl ;move into correct field or al,03 ;set up 8 bits, no parity, 1 stop bit xor ah,ah ;rom bios control code mov dx,_chan_no ;point to port number int 14h ;rom bios interrupt ; ; set current modem status ; mov dx,_port_add add dx,6 ;point to modem status register in al,dx jmp $+2 nop in al,dx ;do it again in case change was waiting mov _linestat,al ; ; enable modem status, rcvr and xmtr interrupts ; sub dx,5 ;point to interrupt enable register mov al,00001011b out dx,al jmp $+2 nop ; ; clear pending interrupts ; inc dx ;point to interrupt identification reg in al,dx ;clear xmtr interrupt by reading iir jmp $+2 nop sub dx,2 ;point to receive data buffer in al,dx ;clear rcvr interrupt by reading rxb jmp $+2 nop ; ; setup dtr, rts & interrupt hardware enable ; add dx,4 ;point to modem control register mov al,00001011b ;enable dtr, rts and interrupt (out 2) out dx,al jmp $+2 nop ; ; enable interrupt in controller. ; if the port address is 2f8, use interrupt 3; otherwise use int 4. ; mov al,ic_imr_sav mov ah,0ffh - 00010000b ;assume int 4 cmp _port_add,02f8h ;com2? jne port1 ;no-go on mov ah,0ffh - 00001000b ;switch to int 3 port1: and al,ah ;enable irq out ic_imr,al jmp $+2 nop ; done: pop es pop dx pop bx pop bp ret ; _drvr_ins endp page ;PUBLIC--------------------------------------------------------------------- ; ; _drvr_rem - remove async interrupt handler ; ;-------------------------------------------------------------------------- _drvr_rem proc near push bp mov bp,sp ; push dx ; cmp drvr_active,1 jne rdone ; ; reinstall system interrupt handler ; push ds ;save current ds mov ah,25h mov al,_hard_int mov dx,old_vct mov ds,old_vct+2 int 21h pop ds ;restore ds ; mov drvr_active,0 rdone: pop dx pop bp ret ; _drvr_rem endp page ;LOCAL---------------------------------------------------------------------- ; ; _async - async interrupt handler ; ;--------------------------------------------------------------------------- _async proc far push bp push ax push bx push cx push dx push si push di push ds push es ; mov di,ss mov si,sp ; mov ax,cs:cdsg mov ss,ax mov es,ax mov ds,ax ; mov ax,offset dgroup:stack mov sp,ax mov bp,ax ; push di push si ; cld ; call _ascode ; pop si pop di mov ss,di mov sp,si ; pop es pop ds pop di pop si pop dx pop cx pop bx pop ax pop bp sti iret ; _async endp page ;PUBLIC--------------------------------------------------------------------- ; ; _clr_int - do a cli from C ; ;--------------------------------------------------------------------------- _clr_int proc near cli ret _clr_int endp ;PUBLIC--------------------------------------------------------------------- ; ; _set_int - do an sti from C ; ;--------------------------------------------------------------------------- _set_int proc near sti ret _set_int endp _text ends end