Power Programmierung 2

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Assembly Source File | 1987-11-22 | 44.2 KB | 1,131 lines

Title vid_ screen Routines by Jerry Joplin [70441,2627] CIS Page ,132 Subttl Usage Notes and Segment Declarations COMMENT * The following routines are a set of direct video-memory access routines. They are much faster than BIOS functions, yet maintain full Microsoft Windows, DESQview, and Topview rules of __good_behaviour__. Programs written using these techniques are fully capable of running as a concurrently executing task in a well behaved window. These routines have been designed for the small and tiny memory models of TURBOC Vers 1.0 and the small memory model for MSC Vers 4.0 and 5.0 * _TEXT segment byte public 'CODE' DGROUP group _DATA,_BSS assume cs:_TEXT,ds:DGROUP,ss:DGROUP _TEXT ends _DATA segment word public 'DATA' _DATA ends _BSS segment word public 'BSS' _BSS ends _TEXT segment byte public 'CODE' assume cs:_TEXT, ds:DGROUP, es:nothing, ss:DGROUP Page ,132 Subttl Procedure declarations public _vid_puts ;Write string w/attr public _vid_putc ;Write character w/attr public _vid_readc ;Read char/attr public _vid_begin ;Begin a video update public _vid_update ;End a video update public _vid_buffc ;Write a char/attr in an update public _vid_memread ;Video memory block read public _vid_memwrite ;Video memory block write public _vid_clearbox ;Clear a window public _vid_scrollbox ;Scroll a window public _vid_drawbox ;Draw a box around a window public _vid_setbox ;Set a box character set public _vid_setpage ;Set the active video page public _vid_setmode ;Set the video mode public _vid_poscurs ;Position the cursor Screen equ 10h Page ,132 Subttl Functions ;------------------------------------------------------------------------- ;Write a null terminated string directly to Video memory ; If a virtual screen buffer is detected then write the ; string to the buffer and update the real display. ; If no virtual screen is detected then blast the string ; directly to video memory without snow for the CGA. ;------------------------------------------------------------------------- StringOfs equ [bp+4] Row equ [bp+6] Col equ [bp+8] Attr equ [bp+10] _vid_puts proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov dh,byte ptr Row ;Determine video address for mov dl,byte ptr Col ; the specified row and column call GetVideoAddr ; as Seg:Offs in ES:DI mov si,StringOfs ;Get the address of the string mov ah,Attr ; and video attribute mov bx,es cmp bx,0b000h ;Video segment = Monochrome? jz Mono_Puts ; yes, then this case is easy cmp bx,0b800h ;Video segment = Color? jnz Buff_Puts ; no, then must be a shadow ; buffer we are writing to ; ; Write string a Non-Monochrome video screen ; accomodating CGA tendancy to snow ; Puts_Next: lodsb ;Load character of string or al,al ;Is it end of the string? jz VS_Puts_Exit ; yes, then exit. mov bx,ax ;Save video word in BX mov dx,03dah ;Prepare to read 6845 cli ; disable interrupts V_Retrace_Puts: in al,dx ; get 6845 status test al,1000b ;Vertical retrace bit set? jnz Write_Puts ; yes, then write it rcr al,1 ; no, wait till horizontal jc V_Retrace_Puts ; retrace bit set H_Retrace_Puts: in al,dx ;Get 6845 status again rcr al,1 ; wait for horizontal jnc H_Retrace_Puts ; retrace bit Write_Puts: mov ax,bx ;Restore screen word stosw ; and move it to the screen sti ;Allow interrupts jmp short Puts_Next ;Continue until null is hit ; ; Write string to a virtual screen buffer and ; update the real screen ; Buff_Puts: push di ;Save beginning buffer offset xor cx,cx ; use CX for character count BuffNext: lodsb ; load next char into AL or al,al ; is it the end of the string? jz BuffWriteExit ; yes, then update buffer. stosw ; else write it to screen inc cx ; and increment the char count jmp short BuffNext ; continue with next char BuffWriteExit: pop di ;Restore buffer offset mov ah,0ffh ; Update the video buffer int Screen ; with chars altered in CX jmp short VS_Puts_Exit ; and exit. ; ; Write string to a monochrome screen ; Mono_Puts: lodsb ;Load character into AL or al,al ; is it the end of the string? jz VS_Puts_Exit ; yes, then exit. stosw ; else write it to screen jmp short Mono_Puts ; continue till null. VS_Puts_Exit: pop si pop di pop bp ;Restore registers ret ; and return _vid_puts endp ;------------------------------------------------------------------------- ;Write a character directly to Video memory ; If a virtual screen buffer is detected then write the ; character to the buffer and update the real display. ; If no virtual screen is detected then write the character ; directly to video memory without snow for the CGA. ;------------------------------------------------------------------------- Char equ [bp+4] Row equ [bp+6] Col equ [bp+8] Attr equ [bp+10] _vid_putc proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov dh,byte ptr Row ;Determine video address for mov dl,byte ptr Col ; the specified row and column call GetVideoAddr ; as Seg:Offs in ES:DI mov al,Char ;Get the character and mov ah,Attr ; video attribute mov bx,es cmp bx,0b000h ;Video segment = Monochrome? jz Mono_Putc ; yes, then use mono routine cmp bx,0b800h ;Video segment = Color? jnz Buff_Putc ; no, then must be a shadow ; buffer we are writing to ; ; Write character to a Non-Monochrome video screen ; accomodating CGA tendancy to snow ; mov bx,ax ;Save video word in BX mov dx,03dah ;Prepare to read 6845 cli ; disable interrupts V_Retrace_Putc: in al,dx ; get 6845 status test al,1000b ;Vertical retrace bit set? jnz Write_Putc ; yes, then write it rcr al,1 ; no, wait for horizonal jc V_Retrace_Putc ; retrace bit H_Retrace_Putc: in al,dx ;Get 6845 status again rcr al,1 ; wait for horizontal jnc H_Retrace_Putc ; retrace bit Write_Putc: mov ax,bx ;Restore screen word mov es:[di],ax ; and move it to the screen sti ;Allow interrupts jmp short VS_Putc_Exit ; and exit. ; ; Write a character to a virtual screen buffer and ; update the real screen ; Buff_Putc: mov es:[di],ax ;Write the char/attribute mov cx,1 mov ah,0ffh ;Update the video buffers int Screen ; one character change jmp short VS_Putc_Exit ; and exit. ; ; Write a character to a monochrome screen ; Mono_Putc: mov es:[di],ax ;Write the char/attr to screen VS_Putc_Exit: pop si pop di pop bp ;Restore registers ret ; and return _vid_putc endp ;------------------------------------------------------------------------- ;Read a character/attribute directly from Video memory ; If a virtual screen buffer is detected then read the ; character from the virtual screen buffer. ; If no virtual screen is detected then read the character ; directly from video memory without snow for the CGA. ;------------------------------------------------------------------------- Row equ [bp+4] Col equ [bp+6] _vid_readc proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov dh,byte ptr Row ;Determine video address for mov dl,byte ptr Col ; the specified row and column call GetVideoAddr ; as Seg:Offs in ES:DI mov bx,es cmp bx,0b000h ;Video segment = Monochrome? jz Mono_Readc ; yes, then use mono routine cmp bx,0b800h ;Video segment = Color? jnz Buff_Readc ; no, then must be a shadow ; buffer we are reading from ; ; Read character from a Non-Monochrome video screen ; accomodating CGA tendancy to snow ; mov dx,03dah ;Prepare to read 6845 cli ; disable interrupts V_Retrace_Readc: in al,dx ; get 6845 status test al,1000b ;Vertical retrace bit set? jnz Read_Readc ; yes, then write it rcr al,1 ; no, wait for horizontal jc V_Retrace_Readc ; retrace bit H_Retrace_Readc: in al,dx ;Get 6845 status again rcr al,1 ; wait for horizontal jnc H_Retrace_Readc ; retrace bit Read_Readc: mov ax,es:[di] ; read char/attr from screen sti ;Allow interrupts jmp short VS_Readc_Exit ; and exit. ; ; Read a character from a virtual screen buffer or ; a monochrome display ; Buff_Readc: Mono_Readc: ;Monochrome and Virtual display mov ax,es:[di] ; reads are simple memory transfers VS_Readc_Exit: pop si pop di pop bp ;Restore registers ret ; and return _vid_readc endp ;------------------------------------------------------------------------- ;Read a block of Video memory from a row and col into a save buffer ; If a virtual screen buffer is detected then read the ; block from the virtual screen buffer. ; If no virtual screen is detected then read the block ; directly from video memory without snow for the CGA. ;------------------------------------------------------------------------- SaveBuff equ [bp+4] Row equ [bp+6] Col equ [bp+8] Count equ [bp+10] _vid_memread proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si push ds mov dh,byte ptr Row ;Determine video address for mov dl,byte ptr Col ; the specified row and column call GetVideoAddr ; as Seg:Offs in ES:DI mov si,di ;Screen will be Source for reads mov di,SaveBuff ; destination is the Savebuff mov ax,ds ; swap ES and DS mov bx,es ; saving video segment in BX mov ds,bx mov es,ax cmp bx,0b000h ;Video segment = Monochrome? jz Mono_MemRead ; yes, then use mono routine cmp bx,0b800h ;Video segment = Color? jnz Buff_MemRead ; no, then must be a shadow ; buffer we are reading from ; ; Read memory block from a Non-Monochrome video screen ; accomodating CGA tendancy to snow ; mov cx,Count Color_MemRead: mov dx,03dah ;Prepare to read 6845 cli ; disable interrupts V_Retrace_MemRead: in al,dx ; get 6845 status test al,1000b ;Vertical retrace bit set? jnz Read_MemRead ; yes, then write it rcr al,1 ; no, wait for horizontal jc V_Retrace_MemRead ; retrace bit H_Retrace_MemRead: in al,dx ;Get 6845 status again rcr al,1 ; wait for horizontal jnc H_Retrace_MemRead ; retrace bit Read_MemRead: movsw ;Save this video char/attr loop Color_MemRead ; and continue with next word jmp short VS_MemRead_Exit ; until through ; ; Read memory block from a virtual screen buffer or ; a monochrome display ; Buff_MemRead: Mono_MemRead: mov cx,Count ;Monochrome and Virtual display rep movsw ; reads are simple memory transfers VS_MemRead_Exit: pop ds pop si pop di pop bp ;Restore registers ret ; and return _vid_memread endp ;------------------------------------------------------------------------- ;Write to a block of Video memory at a row and col from a buffer ; If a virtual screen buffer is detected then write to the ; virtual screen buffer and update the real screen. ; If no virtual screen is detected then write ; directly to video memory without snow for the CGA. ;------------------------------------------------------------------------- SaveBuff equ [bp+4] Row equ [bp+6] Col equ [bp+8] Count equ [bp+10] _vid_memwrite proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov dh,byte ptr Row ;Determine video address for mov dl,byte ptr Col ; the specified row and column call GetVideoAddr ; as Seg:Offs in ES:DI mov si,SaveBuff ;Source is the Savebuff mov bx,es cmp bx,0b000h ;Video segment = Monochrome? jz Mono_MemWrite ; yes, then use mono routine cmp bx,0b800h ;Video segment = Color? jnz Buff_MemWrite ; no, then must be a video buffer ; ; Write a memory block to a Non-Monochrome video screen ; accomodating CGA tendancy to snow ; mov cx,Count Color_MemWrite: mov dx,03dah ;Prepare to read 6845 cli ; disable interrupts V_Retrace_MemWrite: in al,dx ; get 6845 status test al,1000b ;Vertical retrace bit set? jnz Read_MemWrite ; yes, then write it rcr al,1 ; no, wait for horizontal jc V_Retrace_MemWrite ; retrace bit H_Retrace_MemWrite: in al,dx ;Get 6845 status again rcr al,1 ; wait for horizontal jnc H_Retrace_MemWrite ; retrace bit Read_MemWrite: movsw ;Save this video char/attr loop Color_MemWrite ; and continue with next char jmp short VS_MemWrite_Exit ; until through ; ; Write a memory block to a virtual screen buffer and ; update the real screen ; Buff_MemWrite: push di ;Save beginning buffer offset mov cx,Count ; Load character count rep movsw ; store the char/attr's pop di ; restore buffer offset mov cx,Count ; use CX for character count mov ah,0ffh ; Update the video buffer int Screen ; with chars altered in CX jmp short VS_MemWrite_Exit ; and exit. ; ; Write a memory block to a monochrome display ; Mono_MemWrite: mov cx,Count ;Monochrome display writes rep movsw ; are simple memory transfers VS_MemWrite_Exit: pop si pop di pop bp ;Restore registers ret ; and return _vid_memwrite endp ;------------------------------------------------------------------------- ;Start a video screen update ;------------------------------------------------------------------------- _vid_begin proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov bx,0b000h ;Assume monochrome adapter mov ax,40h ;Determine Screen Segment mov es,ax ; address BIOS Data segment cmp byte ptr es:[49h],7 ; monochrome video mode? jz GotBeginSeg ; yes, screen Seg is ok mov bx,0b800h ; no, set Non-Monochrome ; segment address GotBeginSeg: mov es,bx ; ES:DI = assumed video addr xor di,di mov ah,0feh ;Get our process video address int Screen mov VideoSeg,es ;Save the video memory address mov VideoOfs,di ; for following buffer writes mov StartOfs,0ffffh ;Set the initial start offset to ; large value, any writes will ; be to an address below it mov EndOfs,di ;Set the initial end offset to ; start of video memory so any ; write will be at higher address ; above it pop si pop di pop bp ;Restore registers ret ; and return _vid_begin endp ;------------------------------------------------------------------------- ;End a video update ;------------------------------------------------------------------------- _vid_update proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov es,VideoSeg ;Retrieve the starting addr ; of the beginning of the mov di,StartOfs ; altered video memory cmp di,0ffffh ; If nothing has been altered jz VS_Update_Exit ; then theres nothing to update mov cx,EndOfs ;Calculate the number of sub cx,di ; *characters* changed shr cx,1 ; (EndOffs-StartOffs) / 2 inc cx ; add 1 for round off mov ah,0ffh ;Update the video buffer int Screen ; with chars altered in CX VS_Update_Exit: pop si pop di pop bp ;Restore registers ret ; and return _vid_update endp ;------------------------------------------------------------------------- ;Buffer a character to the process virtual screen ;------------------------------------------------------------------------- Char equ [bp+4] Row equ [bp+6] Col equ [bp+8] Attr equ [bp+10] _vid_buffc proc near push bp mov bp,sp push di push si mov dh,byte ptr Row mov dl,byte ptr Col mov di,VideoOfs ;Use values saved in vs_begin mov es,VideoSeg ; as starting video address xor ax,ax ;Calculate screen offset mov al,dh ; load row into AX and BX mov bx,ax shl ax,1 ; avoid MUL instruction for shl ax,1 ; slower 8088 based systems shl ax,1 ; AX = row * 8 shl bx,1 ; BX = row * 2 add bx,ax ; BX = AX + BX = row * 10 shl bx,1 shl bx,1 shl bx,1 ; BX = row * 80 xor dh,dh add bx,dx ; BX = row * 80 + columns shl bx,1 ; account for attribute bytes add di,bx mov al,Char ;Place attr/char in AX mov ah,Attr mov bx,es cmp bx,0b000h ;Use Mono Character display? jz Mono_Buffc ; yes, then branch to it cmp bx,0b800h ;Use Color charcter display? jnz Buff_Buffc ; no, then must be a shadow ; buffer we are writing to mov bx,ax ;Save video word in BX mov dx,03dah ;Prepare to read 6845 cli ; disable interrupts V_Retrace_Buffc: in al,dx ; get 6845 status test al,1000b ;Vertical retrace? jnz Write_Buffc ; yes, then write it rcr al,1 ; no, wait for end of jc V_Retrace_Buffc ; horizontal retrace H_Retrace_Buffc: in al,dx ;Get 6845 status again rcr al,1 ; wait for horizontal jnc H_Retrace_Buffc ; retrace Write_Buffc: mov ax,bx ;Restore screen word mov es:[di],ax ; and move it to the screen sti ;Allow interrupts jmp short VS_Buffc_Exit Buff_Buffc: cmp di,StartOfs ;See if this offset is jae Ofs_greater ; LESS than any previous mov StartOfs,di ; since last call to vs_begin Ofs_greater: cmp di,EndOfs ;See if this offset is jbe Mono_Buffc ; GREATER than any previous mov EndOfs,di ; since last call to vs_begin Mono_Buffc: mov es:[di],ax ; store the attr/char VS_Buffc_Exit: pop si pop di pop bp ;Restore registers ret ; and return _vid_buffc endp ;------------------------------------------------------------------------- ;Draw a box to the process virtual screen ;------------------------------------------------------------------------- TRow equ [bp+8] LCol equ [bp+10] BRow equ [bp+12] RCol equ [bp+14] Attr equ [bp+16] BorderType equ [bp+18] Next equ [bp-2] _vid_drawbox proc near push si push di ;Save register variables push bp mov bp,sp ; address call stack dec sp dec sp ; allocate 1 word pointer variable mov si,LCol ; SI used as column counter mov di,TRow ; DI used as row counter mov cx,BorderType ;Get the address of the lea bx,border0 ; box character set jcxz BoxIndexGot ; if set 0 then already got it GetBoxIndex: add bx,8 ; else add 8 till we got it loop GetBoxIndex BoxIndexGot: mov Next,bx ; save this address in Next ;The Top row of the Box call _vid_begin ; lies in a contigious block ; of screen memory so ; start a screen update DrawTopLeft: push Attr ;Draw the top left character push si ; using vid_buffc push di mov bx,Next push [bx] call _vid_buffc add sp,8 inc word ptr Next ;Point Next to next box char DrawTopLine: inc si ;Move SI to next column cmp si,word ptr RCol ; hit the right side yet? jae DrawTopRight ; yes, then draw top right push Attr ;Draw chars of the top line push si ; using vid_buffc push di mov bx,word ptr Next push [bx] call _vid_buffc add sp,8 jmp short DrawTopLine DrawTopRight: inc word ptr Next ;Point Next to next box char push Attr ;Draw the top right char push si ; using vid_buffc mov ax,di push ax mov bx,Next push [bx] call _vid_buffc add sp,8 call _vid_update ;End this screen 'transaction' inc word ptr Next ;Point Next to next box char DrawRightLine: inc di ;Move DI next row cmp di,word ptr BRow ; hit the bottom yet? jae DrawBottomRight ; yes, then draw bottom right push Attr ;Draw the characters of the push si ; right side using vid_putc push di ; since vertical lines mov bx,Next ; do not lie in a contigious push [bx] ; block of screen memory call _vid_putc add sp,8 jmp short DrawRightLine DrawBottomRight: ;The Bottom row of the Box call _vid_begin ; lies in a contigious block ; of screen memory so ; start a screen update inc word ptr Next ;Point Next to next box char push Attr ;Draw the bottom right push si ; character using vid_buffc push di mov bx,Next push [bx] call _vid_buffc add sp,8 inc word ptr Next ;Point Next to next box char DrawBottomLine: dec si ;Move SI to next column cmp si,word ptr LCol ; hit the left side yet? jbe DrawBottomLeft ; yes, then draw bottom left push Attr ;Draw chars of the bottom push si ; line using vid_buffc push di mov bx,Next push [bx] call _vid_buffc add sp,8 jmp short DrawBottomLine DrawBottomLeft: inc word ptr Next ;Point Next to next box char push Attr ;Draw the bottom left char push si ; using vid_buffc push di mov bx,Next push [bx] call _vid_buffc add sp,8 call _vid_update ;End this screen 'transaction' inc word ptr Next ;Point Next to next box char DrawLeftLine: dec di ;Move up to next row cmp di,word ptr TRow ; hit top yet? jbe DrawBoxExit ; yes, then box is thru push Attr ;Draw the characters of the push si ; left side using vid_putc push di ; since vertical lines mov bx,Next ; do not lie in a contigious push [bx] ; block of screen memory call _vid_putc add sp,8 jmp short DrawLeftLine DrawBoxExit: mov sp,bp pop bp pop di pop si ret _vid_drawbox endp ;------------------------------------------------------------------------- ;Set a box rendition set ;------------------------------------------------------------------------- BorderSet equ [bp+4] UpperLeft equ [bp+6] Top equ [bp+8] UpperRight equ [bp+10] Right equ [bp+12] LowerRight equ [bp+14] Bottom equ [bp+16] LowerLeft equ [bp+18] Left equ [bp+20] _vid_setbox proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si push ds ;Extra segment = data segment pop es mov cx,BorderSet ;Get the address of the box lea di,border0 ; character set to establish jcxz BoxIndexSet ; if set 0 then already got it SetBoxIndex: add di,8 ; else add 8 till we hit it loop SetBoxIndex BoxIndexSet: lea si,UpperLeft ;Point Source index to new box set mov cx,8 ; contains 8 characters cld ; Lets be __forward__ shall we GetBoxChars: lodsw ;Get a word from stack stosb ; and save the low order byte loop GetBoxChars ; as a box character pop si pop di pop bp ;Restore registers ret ; and return _vid_setbox endp ;------------------------------------------------------------------------- ;Clear a box on the video screen ; by invoking BIOS scroll window function ; specifying 0 lines to scroll ;------------------------------------------------------------------------- Urow equ [bp+4] Lcol equ [bp+6] Brow equ [bp+8] Rcol equ [bp+10] Attr equ [bp+12] _vid_clearbox proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov ax,0600h ;Use BIOS scroll window up function ; AL = 0 to blank area jmp short BIOS_Scroll _vid_clearbox endp ;------------------------------------------------------------------------- ;Scroll a box on the video screen ; a specified direction and number of lines ; by invoking BIOS scroll window function ;------------------------------------------------------------------------- Urow equ [bp+4] Lcol equ [bp+6] Brow equ [bp+8] Rcol equ [bp+10] Attr equ [bp+12] Direction equ [bp+14] NumberOfLines equ [bp+16] _vid_scrollbox proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si ;Use BIOS scroll window up function mov ah,Direction ; valid directions are 0 and 1 add ah,6 ; function 6 is up, 7 is down mov al,NumberOfLines ; AL holds number of scroll lines BIOS_Scroll: mov bh,byte ptr Attr ; BH holds video attribute mov ch,byte ptr Urow mov cl,byte ptr Lcol ; CH:CL = top left mov dh,byte ptr Brow ; DH:DL = bottom right mov dl,byte ptr Rcol int screen ; transfer to BIOS pop si pop di pop bp ;Restore registers ret ; and return _vid_scrollbox endp ;------------------------------------------------------------------------- ;Set the active video page ;------------------------------------------------------------------------- Vpage equ [bp+4] _vid_setpage proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov al,byte ptr Vpage ;Get specified page mov VideoPage,al ; save it to avoid overhead of ; get video page requests mov ah,5 ;Use BIOS set video page function int screen ; transfer to BIOS pop si pop di pop bp ;Restore registers ret ; and return _vid_setpage endp ;------------------------------------------------------------------------- ;Establish the video mode ;------------------------------------------------------------------------- Vmode equ [bp+4] _vid_setmode proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov al,byte ptr Vmode ;Get specified mode xor ah,ah ;Use BIOS set video mode function int screen ; transfer to BIOS pop si pop di pop bp ;Restore registers ret ; and return _vid_setmode endp ;------------------------------------------------------------------------- ;Set the cursor to a position on the active video page ;------------------------------------------------------------------------- Row equ [bp+4] Col equ [bp+6] _vid_poscurs proc near push bp mov bp,sp ;Address call parameters and push di ; save register variables push si mov ah,2 ;Use BIOS set cursor pos function mov bh,VideoPage ; in the saved video page mov dh,byte ptr Row ; DH:DL holds position mov dl,byte ptr Col int screen ;Transfer to BIOS pop si pop di pop bp ;Restore registers ret ; and return _vid_poscurs endp ;------------------------------------------------------------------------- ;Retrieve the video buffer address ; On Entry: ; DX = row in DH, column in DL ; Returns ; ES:DI video buffer address ;------------------------------------------------------------------------- GetVideoAddr proc near mov bx,0b000h ;Assume monochrome adapter mov ax,40h ;Determine Screen Segment mov es,ax ; address BIOS Data segment cmp byte ptr es:[49h],7 ; monochrome video mode? jz GotScreenAddr ; yes, screen Seg is ok mov bx,0b800h ; no, set Non-Monochrome ; segment address GotScreenAddr: mov es,bx ; ES:DI =assumed video addr xor di,di mov ah,0feh ;Get our process video int Screen ; memory address xor ax,ax ;Calculate screen offset mov al,dh ; load row into AX and BX mov bx,ax shl ax,1 ; avoid MUL instruction for shl ax,1 ; slower 8088 based systems shl ax,1 ; AX = row * 8 shl bx,1 ; BX = row * 2 add bx,ax ; BX = AX + BX = row * 10 shl bx,1 shl bx,1 shl bx,1 ; BX = row * 80 xor dh,dh add bx,dx ; BX = row * 80 + columns shl bx,1 ; account for attribute bytes add di,bx ;Add the row and column offset ; to the video address offset ret ; and return GetVideoAddr endp _TEXT ends ;------------------------------------------------------------------------- ;vid_ routines data ;------------------------------------------------------------------------- _DATA segment StartOfs dw 0ffffh ;Starting offset in an update Endofs dw ? ;Ending offset in an update VideoOfs dw 0 ;Saved Offset and Segment pointer VideoSeg dw ? ; to the video screen in an update VideoPage db 0 ;Holds the current video page ;Box character sets, defaults: border0 db 8 dup (' ') ; 0 = spaces border1 db 218,196,191,179,217,196,192,179 ; 1 =single line border, border2 db 201,205,187,186,188,205,200,186 ; 2 =double line border. border3 db 8 dup (0) border4 db 8 dup (0) border5 db 8 dup (0) ; 3 - 7 should be set using border6 db 8 dup (0) ; vid_setbox before using border7 db 8 dup (0) _DATA ends end