Simtel MSDOS 1992 June

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Assembly Source File | 1986-09-05 | 13.5 KB | 530 lines

;******************************************************************** ;* ;* GRAPHIC CHARACTER HANDLING ;* ;* Dave Tutelman - 8/86 ;* ;*------------------------------------------------------------------- ;* ;* Fn 6 Scroll up - not yet implemented ;* Fn 7 Scroll down - not yet implemented ;* Fn 9 Write character with attribute ;* Fn 10 Write character normal ;* Fn 14 Write character Teletypewriter style ;* ;* Also includes subroutines to: ;* get_address convert page/row/col to display address ;* do_char write a character to an address on display ;* do_attrib change a display address to some attribute ;* full_screen_scroll used by Fn 14, when it needs to scroll ;* flash momentarily flash to reverse video and back ;* ;******************************************************************** ; INCLUDE hercbios.h ;----------------------------------------------- extrn exit_herc_bios:near public writechar,scroll_up,scroll_down,tty public scr_start,scr_length,num_rows ;------------------------------------ cseg segment public assume cs:cseg,ds:bios_data ; ;************************************************************** ;* ;* FUNCTION 6 & 7 - SCROLL UP & DOWN ;* (Placeholder only - not yet implemented) ;* ;* AL = Number of rows to scroll (if 0, blank scroll area) ;* BH = Fill attribute (we ignore, since writechar destroys old attrib) ;* CX = Upper left corner (CH=row, CL=col) ;* DX = Lower right corner (DH=row, DL=col) ;* ;**************************************************************** ; scroll_up: scroll_down: ; jmp exit_herc_bios page ;******************************************************************** ;* ;* FUNCTION 9 & 10 - WRITE A CHARACTER AT CURRENT CURSOR ;* ;* AL = character code to be written ;* AH = 9 (write char with attribute) or 10 (write char normal) ;* BL = new attribute (limited selection in graphics mode) ;* BH = display page number ;* CX = count of how many characters to write ;* ;******************************************************************** ; writechar: ; ; Get the address corresponding to cursor[page] push bx mov bl,bh ; page to BX xor bh,bh shl bx,1 ; *2 for word pointer mov dx,curs_pos[bx] ; appropriate cursor position to DX pop bx call get_address ; get display address in DI ; wrchar_loop: ; ; Write a character to that address call do_char ; arguments set up already ; ; ; If function 9, modify the character's attributes cmp ah,9 ; Function 9? jne no_attrib ; no, don't do attributes call do_attrib ; yes, and arguments already set up no_attrib: ; inc di ; move to next position, without moving ; the official cursor loop wrchar_loop ; continue until CX count exhausted jmp exit_herc_bios page ;***************************************************************** ;* ;* FUNCTION 14 - TELETYPEWRITER-STYLE CHARACTER WRITE ;* ;* AL = Character to be written ;* ;****************************************************************** ; tty: assume ds:bios_data mov bl,active_page ; active page to BX xor bh,bh mov dx,curs_pos[bx] ; get cursor for active page push bx mov bh,bl ; move page to BH call get_address ; address of character to DI pop bx ; ; ; process the character ; ; check if CR cmp al,13 ; carriage return? jne not_cr mov dl,0 ; go to first column jmp fix_curs ; ; check if LF not_cr: cmp al,10 ; line feed? jne not_lf inc dh ; next line jmp fix_curs ; ; check if BS not_lf: cmp al,8 ; backspace? jne not_bs cmp dl,0 ; already first column? je fix_curs ; yup. do nothing dec dl ; nope. move cursor left one dec di ; also move address pointer left one mov al,32 ; set character to space call do_char ; and write the space, but don't move jmp fix_curs ; ; check if BEL not_bs: cmp al,7 ; bell character? jne not_bl pop es ; restore registers pop di pop si pop dx pop cx pop bx pop ds jmp vid_bios ; ... and use the normal BIOS to ring the bell ; call flash ; can't do BEL standard. Blink display instead ; jmp fix_curs ; ; ordinary printing character, so display it not_bl: call do_char ; write it to screen inc dl ; cursor one to the right ; ; ; now look at the cursor, do what's necessary to ; ; fix it up, and save it away. fix_curs: cmp dl,89 ; beyond last column? jle chk_scroll ; not yet xor dl,dl ; yes. do a CR inc dh ; ... and a LF chk_scroll: cmp dh,cs:num_rows ; now see if we're beyond last row? jl exit_tty ; not yet call full_screen_scroll ; yes. Scroll the screen up one dec dh ; ... and scroll cursor, too. jmp chk_scroll ; exit_tty: mov curs_pos[bx],dx ; save cursor position jmp exit_herc_bios page ;-------------------------------------------------------------------- ; ; GET_ADDRESS SUBROUTINE ; ; BH = display page ; DX = cursor position (DH=row, DL=col) ; ; returns: ; DI = displacement of top row of pixels ; ;-------------------------------------------------------------------- ; get_address: push cx ; save it ; ; compute display address from cursor_pos mov cl,dh ; get row # in cx xor ch,ch shl cx,1 ; begin fast multiply by 90 (1011010 B) mov di,cx shl cx,1 shl cx,1 add di,cx shl cx,1 add di,cx shl cx,1 shl cx,1 add di,cx ; end fast multiply by 90 mov cx,di ; copy answer back to cx shl di,1 ; *2 for ibm graphics mode cmp video_mode,herc_mode jne ibm_ad ; not herc mode add di,cx ; *3 for herc mode ibm_ad: xor ch,ch ; columns in CX mov cl,dl add di,cx ; add in col. address in DI cmp bh,0 ; if page 1, set high-order bit of address je pg0 or di,8000H pg0: ; ; address now in DI ; pop cx ; restore it ret page ;-------------------------------------------------------------------- ; ; DO_CHAR SUBROUTINE ; ; AL = character to write ; DI = diplacement (address) of top row of pixels ; ; Note: SI and ES are destroyed ; ;-------------------------------------------------------------------- ; do_char: push ax push bx push cx push di push ds ; ; ; get scan pattern table pointer into BX cmp video_mode,herc_mode je herc_1 mov bx,offset ibm_pattern ; IBM graphics mode - use appropriate table jmp c_1 herc_1: mov bx,offset herc_pattern ; herc graphics mode - use appropriate table c_1: ; ; ; set up source address registers xor ah,ah ; character to SI mov si,ax IFDEF iAPX286 shl si,3 ; *8 for 8-byte table entry ELSE shl si,1 ; *8 for 8-byte table entry shl si,1 shl si,1 ENDIF ; next, find beginning of table cmp al,7Fh ; ROM or user table? jg u_tbl ; ROM table add si,charbase ; character table base added to offset mov ax,mpx_bios ; BIOS code segment to DS mov ds,ax jmp c_2 u_tbl: ; user table xor ax,ax ; zero (interrupt vector) to DS mov ds,ax mov ax,si ; save table offset in AX assume ds:intvec lds si,user_table ; load DS:SI from interrupt vector add si,ax ; add offset into table base c_2: ; ; ; set up destination address registers mov ax,pixbase ; get display segment in ES mov es,ax ; displacement already in DI ; ; ; ; transfer the character mov ax,di ; save top-row displacement in AX mov cx,8 ; transfer 8 rows cld ; direction = up c_loop: mov di,ax ; top-row displacement add di,cs:[bx] ; add entry from scan-pattern table movsb ; actually transfer a byte and bump SI & DI add bx,2 ; next entry in scan-pattern table loop c_loop ; ; ; if hercules mode, blank the extra rows pop ds ; restore DS to Bios data assume ds:bios_data cmp video_mode,herc_mode jne c_3 ; Hercules mode mov si,ax ; don't need SI. Save top-row displacement xor ax,ax ; zero AX mov cx,4 ; four rows to blank cld c_blnk: mov di,si ; top-row displacement add di,cs:[bx] ; add entry from scan-pattern table stosb ; transfer a zero byte add bx,2 ; next entry in scan-pattern table loop c_blnk c_3: ; ; ; clean up and return pop di pop cx pop bx pop ax ret page ;--------------------------------------------------------------------- ; ; DO_ATTRIB SUBROUTINE ; ; BL = attribute byte ; DI = displacement (address) of top row of pixels ; ES is destroyed ; ; Because attributes don't "just happen" in graphics mode, here's ; what we have to transform them to. ; ; CODE USUALLY MEANS IBM MODE HERC MODE ; 00 invisible invisible invisible ; 01 underline [normal] underline ; 07 normal normal normal ; 0F hi-intens [rev video] [rev video] ; 70 rev video rev video rev video ; ; Anything else displays as normal ; Note that there's no way to make blinking happen. ; ;----------------------------------------------------------------------- ; do_attrib: assume ds:bios_data push ax mov ax,pixbase ; Display base to ES mov es,ax pop ax ; ; ; which attribute, if any? and bl,7Fh ; mask off blink bit cmp bl,0 ; invisible? je invisible cmp bl,0Fh ; reverse video? (instead of bright) je reverse cmp bl,70H ; reverse video? je reverse cmp bl,01 ; underline? je underline ret ; none of the above. Display normal. ; ; ; underline the character underline: cmp video_mode,herc_mode je ul_1 ret ; don't do it for IBM mode ul_1: mov byte ptr es:[di+40B4h],0FFh ; move ones to 11th line of pixel array ; 40B4h is the 11th entry in herc_pattern ret ; ; ; make it invisible invisible: push ax push bx push cx push dx xor ax,ax ; zero the AX cmp video_mode,herc_mode je herc_3 mov bx,offset ibm_pattern ; point to scan pattern jmp inv_1 herc_3: mov bx,offset herc_pattern ; point to scan pattern inv_1: mov dx,di ; save addr of top row of pixels in DX mov cx,8 ; 8 bytes to be moved cld ; direction = up invis_loop: mov di,dx ; top row address add di,cs:[bx] ; add scan-table offset stosb ; move a zero byte add bx,2 ; bump the scan-table pointer loop invis_loop pop dx pop cx pop bx pop ax ret ; ; ; reverse video reverse: push bx push cx push dx cmp video_mode,herc_mode je herc_4 mov bx,offset ibm_pattern ; point to scan pattern mov cx,8 ; 8 scan lines for IBM mode jmp rev_1 herc_4: mov bx,offset herc_pattern ; point to scan pattern mov cx,12 ; 12 scan lines for Hercules mode rev_1: mov dx,di ; save addr of top row of pixels in DX cld ; direction = up rev_loop: mov di,dx ; top row address add di,cs:[bx] ; add scan-table offset not es:byte ptr[di] ; invert one scan line add bx,2 ; bump the scan-table pointer loop rev_loop pop dx pop cx pop bx ret page ;-------------------------------------------------------------- ; ; SUBROUTINE FULL_SCREEN_SCROLL ; ; This scrolls the entire screen up one print line (8 or 12 pixels). ; Actually, we'll protect one line on the bottom (e.g.-function keys). ; ;----------------------------------------------------------------- ; ; ; A few constants, initialized by set_mode num_rows db ? ; number of rows in display ; = 42 (IBM) or 28 (Herc) scr_start dw ? ; 2*90 or 3*90 depending on mode scr_length dw ? ; number of words to transfer in a sweep ; = 41*start /2 = 3690 (IBM) ; = 27*start /2 = 3645 (Herc) ; full_screen_scroll: assume ds:bios_data push ds push ax push cx mov ax,pixbase ; start getting display segment cmp active_page,0 ; page 0? je scr_pg0 add ax,800H ; page 1. bump by half of 64K scr_pg0: mov ds,ax ; save display segment in DS mov es,ax ; ... and in ES ; xor ax,ax ; zero AX call scr_shift mov ax,2000H ; bump interlace counter call scr_shift mov ax,4000H call scr_shift mov ax,6000H call scr_shift ; pop cx pop ax pop ds ret ; ; ; scr_shift does the actual work of scrolling, one set of interlace ; lines at a time. ; scr_shift: cld ; block moves will be UP mov di,ax ; interlace scan ID to DI mov si,ax ; ... and to SI add si,cs:scr_start ; but bump by "start" mov cx,cs:scr_length ; set counter for transfer rep movsw ; and scroll a set of lines xor ax,ax ; set up a zero word mov cx,cs:scr_start ; set counter for one more line shr cx,1 ; /2 for word transfers rep stosw ; and blank the line ret page ;----------------------------------------------------------- ; ; SUBROUTINE FLASH ; ; Flashes the screen inverse video and back to normal. ; Used in place of an audible bell. ; ;------------------------------------------------------------- ; flash: push cx push di push es ; mov di,pixbase ; get display area base cmp active_page,0 ; page 0? je pg0_f add di,800H ; no, page 1 pg0_f: mov es,di ; put resulting pointer to display in ES ; ; ; loop to invert screen xor di,di ; point to beginning of display area mov cx,4000H ; number of words to invert flash_loop_1: not word ptr es:[di] ; invert one location add di,2 ; bump location pointer a word loop flash_loop_1 ; ; ; and invert it back to normal xor di,di ; point to beginning of display area mov cx,4000H ; number of words to invert flash_loop_2: not word ptr es:[di] ; invert one location add di,2 ; bump location pointer a word loop flash_loop_2 ; pop es pop di pop cx ret page ;***************************************************** ;* Data areas for character handling ;***************************************************** ; pixels db 12 dup(?) ; 12 bytes for pixel pattern ibm_pattern dw 0000h,2000h,4000h,6000h,005Ah,205Ah,405Ah,605Ah herc_pattern dw 4000h,6000h,005Ah,205Ah,405Ah,605Ah,00B4h,20B4h blank_pattern dw 0000h,2000h,40B4h,60B4h ; ; cseg ends end