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Assembly Source File | 1988-04-18 | 13.3 KB | 382 lines

; /-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-\ ; | | ; | Terminal in assembler, A86 format | ; | Interrupt driven reception | ; | -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- | ; | Weefus on GEnie or | ; | Keith Rolland 1:321/112.5 | ; | (!) Copywrong 1988 | ; | | ; \-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-/ ; ; jmp BEGIN_PRG ;jump over our data area to the real beginning MESSAGE1 db 07h,0dh,0ah,0ah,0ah,"Press <alt>-q to quit.......",0dh,0ah,0ah,"$" MESSAGE2 db " Arrgg, I spent HOW much time on this?!? $" BUFFER_BOT equ $ BUFFER db 0ffh DUP 00h ;the actual incoming buffer, 255 bytes BUFFER_TOP equ $ BUFFER_TAIL dw 0000h ;used to control where characters are put BUFFER_HEAD dw 0000h ;into and taken from the buffer LINE_CTL_REG = 03fbh ;various memory locations for rs232 registers MODEM_CTL_REG = 03fch LINE_STAT_REG = 03fdh MODEM_STAT_REG = 03feh CHAR_HOLDING_REG = 03f8h BOX_TLCOR = 0c9h ;Ascii graphic characters used for BOX_TRCOR = 0bbh ;making the box. BOX_BLCOR = 0c8H ;TLCOR = TopLeftCORner and so on.... BOX_BRCOR = 0bch BOX_VERT = 0bah BOX_HORZ = 0cdh SPACE = 020h SCROLL_COUNT db 00h ;============================================================================ BEGIN_PRG: mov w[BUFFER_TAIL], offset BUFFER ;set up buffer pointer variables mov w[BUFFER_HEAD], offset BUFFER ;for our circular buffer call CLEAR_SCREEN ;routine that will....... (guess :) call BOX_MAKE ;make our superneato ascii box and message call SETUP ;set up rs232 and new interrupt routines ;***************************************************************************** MAIN_LOOP: call CHECK_INCOMING ;check the buffer, and print any waiting characters call CHECK_OUTGOING ;see if any keystrokes are waiting in the keyboard queue jnc MAIN_LOOP ;if carry flag not set, jump to main loop ;***************************************************************************** cli ;the carry flag is set, indicating an exit request in al,021h ;reset the com1 interrupt bit in the IMR or al,010h ;so that no more com1 ints are performed out 021h,al ;put it back mov dx,LINE_CTL_REG ;line control reg in al,dx ;get byte and al,07fh ;clear bit 7, com1 interrupt enable bit out dx,al ;put it back mov al,00h ;tell the modem we no longer will be operating..... mov dx,MODEM_CTL_REG ;clear modem control reg out dx,al ;do it sti ;re-enable interrupts int 20h ;standard end program interrupt ;----------------------- SETUP: ;direct set-up of registers, no bios or dos calls ;my mom said it was ok............:) mov dx,LINE_CTL_REG ;point to the line control register, it controls a lot. mov al,080h ;turn on bit 7 out dx,al ;send byte dec dx ;point to msb of baud rate divisor dec dx mov al,00h ;msb for any rate > 1200 baud is 00h out dx,al ;send byte dec dx ;point to lsb of baud rate divisor mov al,060h ;lsb for 1200 bps is 60h, use 30h for 2400 bps out dx,al ;send byte mov dx,LINE_CTL_REG ;line control register mov al,0ah ;7/E/1 settings=0ah /use 03h for 8/n/1 out dx,al ;send byte mov dx,offset NEW_INT ;point com1 interrupt to our new routine, NEW_INT mov al,0ch ;interrupt to replace = COM1 mov ah,025h ;dos function number for change-a-vector int 21h ;call dos to change vector in al,021h ;this will enable interrupts by setting the and al,0efh ;com1 interrupt bit in the IMR (don't ask! :) out 021h,al ;IMR is the Interrupt Mask Register cli ;we don't want to be disturbed during this... mov dx,LINE_CTL_REG ;point to line control register, rs232 in al,dx ;get byte and al,07fh ;set high bit out dx,al ;and put it back dec dx dec dx ;move to the rs232 interrupt enable register mov al,01h ;set it to interrupt when data recieved out dx,al ;put it back inc dx inc dx ;move to modem control register |could have done ....| inc dx ;set it for using interrupts |mov dx,MODEM_CTL_REG| mov al,08h ;bit #3 high out dx,al ;put it back sti ;re-enable normal interrupts mov dx,offset MESSAGE1 ;print how-to-exit message mov ah,09h ;via dos int 21h ret ;end of set-up ;----------------------- CHECK_INCOMING: mov bx,w[BUFFER_TAIL] ;check to see if anything cmp bx,w[BUFFER_HEAD] ;is in the buffer.... je ret ;jump if nothing ready mov al,b[bx] ;character is ready, get it in al inc bx cmp bx,BUFFER_TOP ;if buffer_head is at the top of the jne >L17 ;buffer, we must point it to the other end mov bx,BUFFER_BOT L17: mov w[BUFFER_TAIL],bx ;place new buffer tail in storage cmp al,1bh ;is char an <escape>? jne >L13 ;no, so jump, otherwise..... mov al,0dbh ;change it to a graphic char. No vt100/ansi stuff allowed! L13: ; this is a *real* simple program! :) mov dl,al ;dos wants the char in dl to print it mov ah,02h ;dos print function int 21h ;call dos ret ;end check_incoming ;----------------------- CHECK_OUTGOING: call CK_FOR_KEY ;subroutine checks for keypress via bios interrupt je ret ;no key pressed, return to main_loop jnc >L4 ;no exit request pending so jump ahead ret ;carry set, so just return and main_loop will act on it L4: push bx ;push these on stack push dx ;as they will be used push cx ;here internally mov bl,al ;put keypress in bl temporarily mov dx,MODEM_CTL_REG ;point to modem control register mov al,0bh ;tell modem we want to send out dx,al ;put byte in the register mov dx,MODEM_STAT_REG ;point to modem status register WAIT_FOR_CLR: in al,dx ;get modem status test al,010h ;test for modems 'clear-to-send' line (bit #4) jne >L5 ;no problems so jump loop WAIT_FOR_CLR ;wait for ok (modem is presently busy) L5: mov dx,LINE_STAT_REG ;point to line status register OK_STATUS: in al,dx ;get status byte test al,020h ;test bit #5, 'transmit register empty' jne >L6 ;it's empty,so it's ready for another character loop OK_STATUS ;it is full, so loop until it is empty L6: mov al,bl ;put keypress in al mov dx,CHAR_HOLDING_REG ;point to transmitter holding register out dx,al ;put keypress in transmit register, where it pop cx ;automagicly will be sent upon it's way pop dx ;restore these from stack pop bx ret ;end check_outgoing ;----------------------- NEW_INT: ;Our New Interrupt Handler cli ;this interrupt routine is called by the hardware push ax ;every time a character is recieved via rs232 push bx push dx ;save registers on stack push si push ds mov ax,cs ;make sure data seg is code seg mov ds,ax mov dx,CHAR_HOLDING_REG ;recieve register, the incoming char is held here in al,dx ;get byte, the incoming character, from register mov bx,w[BUFFER_HEAD] ;get present buffer head position in bx mov si,bx ;and then increase bx to point to where inc bx ;the next character will be placed cmp bx,BUFFER_TOP ;if BUFFER_HEAD=BUFFER_TOP, we make it BUFFER_BOT jne >L10 ;next char goes somewhere in the middle of the buffer mov bx,BUFFER_BOT ;here we reset BUFFER_HEAD to BUFFER_BOT L10: cmp bx,w[BUFFER_TAIL] ;if BUFFER_HEAD=BUFFER_TAIL, we have no more room je >L9 ;in the buffer, ie a buffer overrun has occured! ;in this case, we don't store the incoming char. ;ideally, at this point we should call an error ;handling routine, but you can write that. :) mov b[si],al ;put byte in buffer if everything is ok mov w[BUFFER_HEAD],bx ;point buffer_head to new head-of-buffer L9: mov al,020h ;tell the hardware we are through with this interrupt out 020h,al ;by doing this. Only with hardware related ints. pop ds pop si pop dx pop bx pop ax sti iret ;end new_int ;----------------------- CK_FOR_KEY: mov ah,01h ;use int 16h function #01 to test for int 16h ;keypress available je ret ;none ready yet so return pushf mov ah,00h ;use function #0 to get the keypress int 16h popf clc ;clear it before testing cmp al,00h ;is the keypress an extended code? jne ret ;no, so return to check_outgoing cmp ah,010h ;we have an extended code now- is it <alt>-q? jne ret ;no, so we will let the odd code go through for now stc ;yes, it is <alt>-q, so we set the carry flag and return ret ;end ck_for_key ;----------------------- CLEAR_SCREEN: ;the hard way! mov ah,02h ;use bios video to mov bh,00h ;set cursor position to top left mov dx,00h ;of screen int 10h ;bios function 02h ; mov ah,09h ;now using function 09h mov cx,0800h ;print a space char 0800h times, ~2000d... mov al,20h ;20h = space char mov bl,07h ;attribute of character int 10h ;clear it! ; mov ah,02h ;now let's put the mov bh,00h ;cursor back up in mov dx,00h ;the upper left corner int 10h ;bios video function ret ;end clear_screen ;------------------------------------------------- ;******************************* ;* Following are used to make * ;* the ascii box. Is it worth * ;* all of the programming? * ;******************************* PRINT_MANY: mov ah,02h ;load dl with character to be printed PRINT_MORE: int 21h ;and cx with the number of times it dec cx jcxz ret ;should be printed jmp PRINT_MORE ;----------------------- PRINT_ONE: mov ah,02h ;load dl with character int 21h ret ;----------------------- POSITION: MOV dl,SPACE mov cx,0ah call PRINT_MANY ret ;----------------------- CR_LF: mov ah,02h mov dl,0dh int 21h mov dl,0ah int 21h ret ;----------------------- SIDES: ;symbols make for good reading! call POSITION mov dl,BOX_VERT call PRINT_ONE mov dl,SPACE mov cx,03ah call PRINT_MANY mov dl,BOX_VERT call PRINT_ONE call CR_LF ret ;----------------------- BOX_TOP: call POSITION mov dl,BOX_TLCOR call PRINT_ONE mov dl,BOX_HORZ mov cx,03ah call PRINT_MANY mov dl,BOX_TRCOR call PRINT_ONE call CR_LF ret ;----------------------- BOX_BOT: call POSITION mov dl,BOX_BLCOR call PRINT_ONE mov dl,BOX_HORZ mov cx,03ah call PRINT_MANY mov dl,BOX_BRCOR call PRINT_ONE ret ;----------------------- BOX_MAKE: call CR_LF call CR_LF call BOX_TOP call SIDES call POSITION mov dl,BOX_VERT call PRINT_ONE lea dx,MESSAGE2 ;set up for dos' print-string routine mov ah,09h ;dos function number for same int 21h ;do it mov dl,BOX_VERT call PRINT_ONE call CR_LF call SIDES call BOX_BOT call CR_LF call SCROLL_DOWN call SCROLL_UP ret ;end box_make. Not exactly elegant, huh? :) ;----------------------- SCROLL_UP: mov SCROLL_COUNT,0fh ;number of lines to scroll DO_SCROLL: mov ah,00h ;get time of day int 01ah ;tod interrupt add dx,01h ;delay value mov bx,dx ;store ending value in bx push ax push bx mov ah,06h ;scroll up using bios function 6 mov al,01h ;number of rows to scroll up mov cx,00h ;cl=top left row cl=top left col mov dh,018h ;b r row mov dl,050h ;b r col mov bh,07h ;attribute of cleared line int 10h ;do it pop bx pop ax WAIT_HERE: int 01ah ;check tod to see if delay is over cmp dx,bx jne WAIT_HERE dec SCROLL_COUNT mov al,SCROLL_COUNT jnz DO_SCROLL ret ;----------------------- SCROLL_DOWN: mov SCROLL_COUNT,0fh ;number of lines to scroll DO_SCROLL2: mov ah,00h ;get time of day int 01ah ;tod interrupt add dx,01h ;delay value mov bx,dx ;store ending value in bx push ax push bx mov ah,07h ;scroll down using bios function 7 mov al,01h ;number of rows to scroll down mov cx,00h ;cl=top left row cl=top left col mov dh,018h ;b r row mov dl,050h ;b r col mov bh,07h ;attribute of cleared line int 10h ;do it pop bx pop ax WAIT_HERE2: int 01ah ;check tod to see if delay is over cmp dx,bx jne WAIT_HERE2 dec SCROLL_COUNT mov al,SCROLL_COUNT jnz DO_SCROLL2 ret ;-----------------------