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Assembly Source File | 1986-04-06 | 20.3 KB | 458 lines

;=================================================== ; module ZapStuff ; ; Module of external procedures for Turbo Pascal. ; Provides high speed direct write screen output. ; ; In Turbo, declare as: ; ; procedure ZapStuff; ; external 'zapstuff.com'; ; ; procedure ZapStr(var Str: AnyString; Row, Column, Attribute, Video: byte); ; external zapstuff[0]; ; ; procedure ZapClrEOL(Row, Column, Attribute, Video: byte); ; external zapstuff[3]; ; ; procedure ZapClrBox(ulrow, ulcolumn, lrrow, lrcol, attribute: byte); ; external zapstuff[6]; ; ; See page 211 of the Turbo Pascal version 3 manual for ; a discussion of this declaration syntax. ;=================================================== bios_data equ 40H equip_flag equ [10H] crt_status equ 3DAH ;crt status port on 6845 controller chip mono_seg equ 0B000H color_seg equ 0B800H ;========================================================== ; The following structures mimic the contents of the stack ; for calls to each of the procedures. Note that byte ; parameters occupy an entire word on the stack. ;========================================================== strstack struc ;simulate stack contents str_old_bp dw 0000H ;saved bp register str_ret_addr dw 0000H ;return address to turbo pascal str_video dw 0000H ;5th param: video output method str_attrib dw 0000H ;4th param: attribute byte str_col dw 0000H ;3rd param: column str_row dw 0000H ;2nd param: row str_str_offs dw 0000H ;1st param: offset of string str_str_seg dw 0000H ;1st param: segment of string endstruc eolstack struc eol_old_bp dw 0000H ;saved bp register eol_ret_addr dw 0000H ;return address to turbo pascal eol_video dw 0000H ;4th param: video output method eol_attrib dw 0000H ;3rd param: video attribute eol_col dw 0000H ;2nd param: column eol_row dw 0000H ;1st param: row endstruc cbstack struc cb_old_bp dw 0000H ;saved bp register cb_ret_addr dw 0000H ;return address to turbo pascal cb_attrib dw 0000H ;5th param: video attribute cb_lrc dw 0000H ;4th param: lower right column cb_lrr dw 0000H ;3rd param: lower right row cb_ulc dw 0000H ;2nd param: upper left column cb_ulr dw 0000H ;1st param: upper left row endstruc ;================================== ; Entry Point ; ; Jump table to various procedures ;================================== org 0 enterstr jmp zapstr ;print a string enterclreol jmp zapclreol ;clear to the end of line enterclrbox jmp zapclrbox ;clear out a defined area ;======================================================================= ; procedure ZapStr(var Str: AnyString; Row, Column, Attribute, Video: byte); ; ; Outputs a string at the specified screen location, using the given attribute. ; ; The output method depends on the value of parameter VIDEO: ; ; 0 = direct write to hardware, no delay ; 1 = direct write to hardware, but only during screen retrace ; 2 = write via BIOS ;======================================================================== zapstr proc near push bp ;establish stack mov bp, sp ; addressability push ds ;save state push es ; ditto lds si, str_str_offs[bp] ;set up to access string xor ch, ch ;CX <== length of string mov cl, [si] ; ditto cmp cl, 0 ;any characters to write? je str_exit ;exit if not inc si ;SI <== pointer to first char mov dl, str_video[bp] ;which video method? cmp dl, 2 ; -BIOS calls? jl str_direct ; if not use direct write call str_bios ; if so, use bios calls jmps str_exit ; and exit ;===================================== ; Set up for both direct write flavors ; After this fragment, the following ; register assignments hold: ; ; ES:DI pointer into video buffer ; DS:SI pointer to 1st string character ; CX: length of string ; AH: video attribute byte ; DL: video output method ;===================================== str_direct xor ah, ah ;AX <== column number mov al, str_col[bp] ;get column xor bh, bh ;BX <== row number mov bl, str_row[bp] ;get row call calc_offset ;DI <== offset into buffer call set_video_seg ;set up ES to access video buffer mov ah, str_attrib[bp] ;AH <== video attribute jc str_use_dw ;monochrome always direct write rcr dl ;retrace only mode? jc str_use_dwr ;yes str_use_dw call str_dw ;else use direct write jmps str_exit ;and done str_use_dwr call str_dwr ;use direct write/retrace ;fall through to exit str_exit pop es ;restore state pop ds ; ditto pop bp ; ditto ret 12 ;clear params and return endp ;zapstr ;================================================= ; STR_BIOS ; ; Write string to the screen using BIOS calls. ; Slow as a dog, but safe. ; ; Assumptions: ; ; DS:SI pointer to string ; CX length of string ;================================================== str_bios proc near mov di, cx ;DI <== string length mov ah, 03 ;get current cursor position mov bh, 0 ;active page number int 10H ;call BIOS push dx ;save cursor position for restore mov dl, str_col[bp] ;get column dec dl ;correct for 0,0 origin mov dh, str_row[bp] ;get row dec dh ;correct for 0,0 origin mov bl, str_attrib[bp] ;get attribute byte mov cx, 1 ;write only one char per call mov bh, 0 ;work on page 0 str_bios_loop mov ah, 2 ;set cursor position int 10H ;with BIOS call lodsb ;AH <== next character mov ah, 9 ;write char/attrib int 10H ;with BIOS call inc dl ;bump current column dec di ;used up one char jnz str_bios_loop ;loop til out of chars pop dx ;restore cursor mov ah, 2 ; ditto int 10H ; ditto ret ;and return endp ;==================================================== ; Str_DW ; ; Full speed direct write of string to video buffer. ; ; Assumptions: ; ; DS:SI points to first character of string ; ES:DI points to desired location in video buffer ; CX has length of string ; AH has desired video attribute byte ; ; Note that we read char *bytes* from the string, ; but write char/attrib *words* to buffer. ;==================================================== str_dw proc near cld ;8088 --> autoincrement mode str_dw_loop lodsb ;get a char from string stosw ;put char and attrib in buffer loop str_dw_loop ;continue till done ret ;done, so exit endp ;==================================================== ; Str_DWR ; ; String direct write during retrace. ; ; Assumptions: ; ; DS:SI points to first character of string ; ES:DI points to desired location in video buffer ; CX has length of string ; AH has desired video attribute byte ;===================================================== str_dwr proc near ;preload stuff for fast action mov bh, 9 ;mask to detect both retraces mov dx, crt_status ;pointer to crt controller chip cld ;8088 --> autoincrement mode str_stall in al, dx ;throw away any current horiz. rcr al ;retrace so we catch the next jc str_stall ;*full* one. This one may be ;half over already. lodsb ;get the next char mov bl, al ;save it, we need AL cli ;we're busy, let the phone ring str_wait in al, dx ;watch for retrace and al, bh ;either horiz or vert jz str_wait ;not yet? loop mov al, bl ;recover char stosw ;stuff it into the buffer sti ;answer the phone loop str_stall ;loop til done ret endp ;============================================ ; ZapClrEOL ; ; Starting from the indicated row and column, ; clear to the end of the line. ;============================================ zapclreol proc near push bp ;establish stack mov bp, sp ; addressability push ds ;save state push es ; ditto mov dl, eol_video[bp] ;which video method? cmp dl, 2 ;bios call? jne eol_direct ;if not, use direct write call eol_bios ;otherwise use bios calls jmps eol_exit ;====================================== ; Set up for both direct write flavors ;====================================== eol_direct mov cx, 81 ;calculate bytes to clear mov ax, eol_col[bp] ;AX <== column mov bx, eol_row[bp] ;BX <== row sub cx, ax ;CX <== bytes to clear call calc_offset ;DI <== offset into buffer call set_video_seg ;set up ES to access video buffer mov ah, eol_attrib[bp] ;AH <== video attribute mov al, ' ' ;fill with spaces jc eol_use_dw ;monochrome always direct write rcr dl ;retrace only mode? jc eol_use_dwr ;yes eol_use_dw call eol_dw ;no, use direct write jmps eol_exit ;then exit eol_use_dwr call eol_dwr ;use write during retrace jmps eol_exit ;then exit eol_exit pop es ;restore state pop ds ; ditto pop bp ; ditto ret 8 ;clear params and return endp ;zapclreol ;=============================================== ; Char_DW ; ; Direct write of character(s) to video buffer. ; Assumptions: ; ; ES:DI pointer into video buffer ; AX char/attribute ; CX repetition factor ;=============================================== eol_dw proc near cld ;8088 <== autoincrement mode rep ;do it stosw ret endp ;=============================================== ; EOL_DWR ; ; Direct write of character(s) to video buffer, ; during retrace interval. ; Assumptions: ; ; ES:DI pointer into video buffer ; AX char/attribute ; CX repetition factor ;=============================================== eol_dwr proc near ;preload stuff for fast action mov bl, al ;save character mov bh, 9 ;mask to detect both retraces mov dx, crt_status ;pointer to crt controller chip cld ;8088 --> autoincrement mode eol_stall in al, dx ;throw away any current horiz. rcr al ;retrace so we catch the next jc eol_stall ;*full* one. This one may be ;half over already. cli ;we're busy, let the phone ring eol_wait in al, dx ;watch for retrace and al, bh ;either horiz or vert jz eol_wait ;not yet? loop mov al, bl ;recover char stosw ;stuff it into the buffer sti ;answer the phone loop eol_stall ;loop til done ret endp ;============================================= ; EOL_BIOS ; ; Write character(s) to screen using BIOS call. ;============================================= eol_bios proc near mov ah, 03 ;current cursor position? mov bh, 0 ; on page 0 int 10H ; with BIOS call push dx ; save position on stack mov cx, 81 ;calculate bytes to clear mov dx, eol_col[bp] ;AX <== column mov ax, eol_row[bp] ;DX <== row sub cx, dx ;CX <== bytes to clear mov dh, al ;DH,DL <== row, column dec dh ;correct for 0,0 origin dec dl ; ditto mov ah, 2 ;set cursor position mov bh, 0 ;work on page 0 int 10H mov al, ' ' ;fill with space chars mov bl, eol_attrib[bp] ;get video attribute for clear mov ah, 9 ;call BIOS for write operation int 10H mov ah, 02 ;restore cursor position mov bh, 0 ; ditto pop dx ; ditto int 10H ; ditto ret ;and exit endp ;============================================== ; ZapClrBox ; ; Clears the specifed area of the video screen. ;============================================== zapclrbox proc near push bp ;establish stack mov bp, sp ; addressability mov ch, cb_ulr[bp] ;define upper left corner dec ch ;BIOS defines upper left 0,0 mov cl, cb_ulc[bp] ; dec cl mov dh, cb_lrr[bp] ;define lower right corner dec dh mov dl, cb_lrc[bp] ; ditto dec dl mov bh, cb_attrib[bp] ;attribute to fill with mov ax, 0600H ;scroll entire window up int 10H ;call bios pop bp ; ditto ret 10 ;clear params and return endp ;zapclreol ;=========================================== ; SET_VIDEO_SEG ; ; Points ES at the appropriate video buffer ; depending on which display adapter is installed. ; Returns with carry flag clear if color card, ; set for monochrome. ;=========================================== set_video_seg proc near ;points ES at video buffer push ds ;set up to read equipment flag mov ax, bios_data ; ditto mov ds, ax ; ditto mov ax, equip_flag ;get flag and ax, 30H ;look at monitor bits only cmp ax, 30H ;is this the monochrome monitor? je set_video_mono ;yep, skip. mov ax, color_seg ;nope. Use color segment mov es, ax clc ;set carry to indicate color jmps set_video_exit ;and exit set_video_mono mov ax, mono_seg ;yep, use monochrome segment mov es, ax stc ;set carry to indicate monochrome set_video_exit pop ds ret endp ;======================================================== ; CALC_OFFSET ; ; Input: AX screen column ; BX screen row ; ; Output: DI offset into video buffer ; AX trash ; BX trash ; ; Shifts and adds are used in place of multiplication ; for optimum speed. MUL requires a minimum of 74 clocks. ; The optimized "multiply by 160" sequence uses only 19 clocks. ;=============================================================== calc_offset proc near dec bx ;rows past #1 mov di, bx ;multiply row by 160 shl di ;times 2 shl di ;times 2 makes 4 add di, bx ;1 more makes 5 shl di ;times 2 makes 10 shl di ;times 2 makes 20 shl di ;times 2 makes 40 shl di ;times 2 makes 80 shl di ;times 2 makes 160 dec ax ;columns past #1 shl ax ;column x 2 (2 bytes/char) add di, ax ;di now has offset in buffer ret ;return to caller endp