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Assembly Source File | 1994-04-11 | 48.6 KB | 1,308 lines

; vga_font: Some primitives for working with text mode evga fonts. ; ; To use this system with the higher-level unit, V_FONT_U, first call ; FontInit, then use the graphic primitives in the standard fashion. ; I.e., Line(0,0,639,399) to draw a diagonal line. The ClearChars ; procedure is used to de-allocate all of the characters that have ; been used to draw any graphic image on the screen, and clear the ; screen to the way it was when you used FontInit. ; ; Memory required: The main program must declare two areas of memory: ; One to be used to store the contents of the current screen (4096 bytes), ; and another to store the 384-element character set (6144 bytes). ; Procedure headers are clearly marked as to which buffers should ; be used with which procedure. ; ; Specifications: ; - Programmed for 80x25 color EGA or VGA text modes only. ; - Works with resolutions of 640x200, 640x350, and 640x400 ; - Redefines up to 384 characters, starting with character number 511 ; and working down to character number 128. Extended characters are ; used which means that only 8 colors can be controlled directly. ; - Two major primitives supported are Line and Ellipse, as well as ; many other less-significant ones. data segment public ; Line variables: delta_x dw ? delta_y dw ? halfy label word halfx dw ? count dw ? ; Temporary variables: Temp dw ? Temp2 dw ? ; Internal control variables: extrn SizeFor128Chars:word ; Global variables: extrn Buffer: dword ; Font buffer extrn TotalUsed: word ; Total # of allocated chars extrn CharsUsed: byte ; Array of 384 character flags extrn MaxX: word ; Maximum X coordinate extrn MaxY: word ; Maximum Y coordinate extrn Points: byte ; # of bytes per character ; Ellipse variables: even t_e_lo dw ? t_e_hi dw ? r1_lo dw ? r1_hi dw ? r2_lo dw ? r2_hi dw ? y_p_lo dw ? y_p_hi dw ? max_x dw ? c_x dw ? c_y dw ? xe dw ? ye dw ? portion db ? Old_BP dw ? data ends Code segment public assume cs:code,ds:data public Line public Freeze public Unfreeze public Ellipse public Hlin public Vlin public Box public OpenBox public MaskColors public Pset public Make512chars public GetScrn public PutScrn public WriteFont public FontInit public ClearChars public Make8bitChars public Make9bitChars Make8bitChars proc far ; Calling sequence: Make8bitChars(Lines: integer); ; This procedure sets the BIOS video mode so that the character generator ; displays only 8 pixels per character. Two modes support this: a 350 ; line mode, and a 200 line mode. ; Note: Lines can be 350 or 200. Lines equ word ptr [bp+6] push bp mov bp,sp mov ah,12h mov bl,30h cmp Lines,200 jz Set200lines mov al,1 ; 350 scan lines int 10h mov MaxY,349 mov Points,14 mov SizeFor128chars,128*14 jmp short ExitM8 Set200lines: mov al,0 int 10h mov MaxY,199 mov Points,8 mov SizeFor128chars,128*8 ExitM8: pop bp ret 2 Make8bitChars endp Make9bitChars proc far ; 400-line mode. ; Configures the BIOS to program the character generator to display 9 ; pixels for every 8-bit character. Doing this adds a blank vertical line ; to the right of every displayed character, except for the ones designated ; as border characters which have their rightmost pixels extended to the ; ninth position. Using graphics with this mode is more difficult than ; with the 200 & 350 line modes since the programmer must be able to ; deal with the problem of having blank spaces in an otherwise solid ; graphic. Sometimes this effect might actually be beneficial. As for ; diagonal or vertical lines, this effect won't be noticed as much. Keep ; in mind that the screen is still 640 pixels wide, and all pixels will ; be displayed as usual; it's just that there are added blanks. mov ah,12h mov bl,30h mov al,2 ; 400 scan lines int 10h mov MaxY,399 mov Points,16 mov SizeFor128chars,128*16 ret Make9bitChars endp ClearChars proc far ; Calling sequence: ClearChars(ScrnBuf: pointer); ; Display original screen (in ScrnBuf), clear the font, and de-allocate ; all of the characters. Note that the video page gets set to page 0. ScrnBuf equ [bp+6] push bp mov bp,sp cld mov ax,ds mov es,ax mov di,offset CharsUsed mov cx,192 mov ax,0 rep stosw mov TotalUsed,0 les di,Buffer mov cx,0c00h rep stosw push word ptr ScrnBuf[2] push word ptr ScrnBuf call far ptr PutScrn call far ptr WriteFont pop bp ret 4 ClearChars endp FontInit proc far ; Calling sequence: FontInit(FontBuffer,ScrnBuffer: pointer); ; Initializes the font information. FontBuffer is a pointer to a ; 6144-byte array used to store the font. ScrnBuffer is a pointer to ; a 4096-byte array used to store the current screen. PutScrn & GetScrn ; are alternate ways of using ScrnBuffer. FontInit also configures the ; BIOS to handle 512-character fonts, 384 of which are used for VGA_FONT. ScrnBuffer equ [bp+6] FontBuffer equ [bp+10] push bp mov bp,sp mov TotalUsed,0 les di,FontBuffer mov word ptr Buffer,di mov word ptr Buffer[2],es push word ptr ScrnBuffer[2] push word ptr ScrnBuffer call far ptr GetScrn cld mov ax,ds mov es,ax mov di,offset CharsUsed mov ax,0 mov cx,192 rep stosw les di,Buffer mov cx,0c00h rep stosw call far ptr Make512chars pop bp ret 8 FontInit endp WriteFont proc far ; Uses the BIOS to write the font information (contained in Buffer) to the ; EVGA adapter. This procedure has the unfortunate consequence of setting ; the video page to page 0 (among other things). This makes it more difficult ; to stop flickering since the primary way to achieve animation is to use ; the Freeze & UnFreeze procedures to copy the screen to another page and ; switch to it, thereby effectively "freezing" the screen until ; page 0 is switched back. WriteFont will do this switching -- although ; it is usually not the correct time to be doing it. push bp mov ax,1100h mov bh,Points mov bl,0 mov cx,128 mov dx,128 les bp,Buffer int 10h mov ax,1100h mov bh,Points mov bl,1 mov cx,256 xor dx,dx les bp,Buffer add bp,SizeFor128chars int 10h pop bp call far ptr Make512chars ret WriteFont endp GetScrn proc far ; Calling sequence: GetScrn(SBuffer: pointer); ; Reads the screen into the 4096-byte buffer pointed to by SBuffer. ; Copies all character codes & attributes. In the future, ClearChars ; can use this screen to switch to in order to get a clean slate. ; This method allows text to remain constant while graphics get ; cleared. SBuffer equ [bp+6] push bp mov bp,sp push ds cld mov si,0 mov ax,0b800h mov ds,ax les di,SBuffer mov cx,2048 rep movsw pop ds pop bp ret 4 GetScrn endp PutScrn proc far ; Calling sequence: PutScrn(SBuffer: pointer); ; Opposite of GetScrn; transfers SBuffer to the screen. SBuffer equ [bp+6] push bp mov bp,sp push ds cld lds si,SBuffer mov di,0 mov ax,0b800h mov es,ax mov cx,2048 rep movsw pop ds pop bp ret 4 PutScrn endp Make512chars proc far ; Configures the BIOS for 512-element fonts. The lower 256 characters ; remain in bank 0 while the upper 256 characters are in bank 1. mov ax,1103h mov bl,4 int 10h ret Make512chars endp PutChar proc near ; Calling sequence: PutChar(CharNo: integer; Color,x,y: byte); ; Displays CharNo at the specified x,y coordinate. x & y are given ; as character positions, based on a resolution of 80x25. The attribute ; of the character is in Color. CharNo can be anywhere from 0 to 511. y equ byte ptr [bp+4] x equ byte ptr [bp+6] Color equ byte ptr [bp+8] CharNo equ word ptr [bp+10] push bp mov bp,sp mov bx,CharNo cmp bx,255 jbe Less255 or Color,8 jmp short SkipNextPC Less255: and Color,0f7h SkipNextPC: mov si,80 mov al,y xor ah,ah xor dx,dx mul si add al,x adc ah,0 shl ax,1 mov si,ax mov ax,0b800h mov es,ax mov ah,Color mov al,bl mov es:[si],ax pop bp ret 8 PutChar endp WriteDot proc near ; Calling sequence: WriteDot(CharNo,x,y: integer; Value,Color: byte); ; Sets a pixel of a particular character given in CharNo. The x & y ; values specified are offsets into the character matrix based on ; resolutions of 8x8, 8x14, and 8x16. Value is either a 1 or a 0 and ; represents the value of the pixel. Color is a standard text-mode attribute. ; CharNo must be in the range of 128 through 511. Color equ byte ptr [bp+4] Value equ byte ptr [bp+6] y equ word ptr [bp+8] x equ word ptr [bp+10] CharNo equ word ptr [bp+12] push bp mov bp,sp push CharNo mov ax,x and ax,7 push ax mov ax,y div Points mov Temp,ax mov al,ah xor ah,ah push ax mov al,Value push ax call ModifyPixel cmp ax,0 ; Is character blank or not? jz ContWD ; Not blank; continue mov CharNo,32 ; It's blank, and a space ContWD: push CharNo mov al,Color xor ah,ah push ax mov ax,x mov cl,3 shr ax,cl push ax and Temp,0ffh push Temp call PutChar pop bp ret 10 WriteDot endp GetNewChar proc near ; Calling sequence: GetNewChar: integer; ; This function returns and allocates a new character to be used for ; graphics display. GetNewChar starts from character 511 and goes ; backwards to character 128, thereby allowing the program to be ; easily changed to allow fewer characters to be displayed (and ; use the remaining characters as the symbols that IBM intended them ; to be). TotalUsed gets incremented. mov si,(offset CharsUsed)+383 std mov bx,128 WhileLoop: cmp bx,511 ja LimitExceeded lodsb cmp al,1 jnz FoundSpot inc bx jmp short WhileLoop FoundSpot: mov ax,639 sub ax,bx mov bx,ax sub bx,128 mov CharsUsed[bx],1 inc TotalUsed push ax mov al,Points xor ah,ah mul bx les di,Buffer add di,ax mov cl,Points xor ch,ch shr cl,1 cld xor ax,ax rep stosw pop ax ret LimitExceeded: xor ax,ax ret GetNewChar endp SeeIfSpace proc near ; Search the currect character (pointed to by Tmp2) to see if it is blank. ; If it is, de-allocate character from list, and return 1 in AX. ; If it is not blank, return 0 in AX. SeeIfSpace is for use by ; ModifyPixel. cld les di,Buffer add di,Temp2 mov cl,Points xor ch,ch shr cl,1 xor ax,ax repe scasw or cx,cx jnz ExitSIS0 mov si,[bp+10] sub si,128 mov CharsUsed[si],0 dec TotalUsed mov ax,1 ExitSIS0: ret SeeIfSpace endp ModifyPixel proc near ; Calling sequence: ModifyPixel(CharNo: integer; x,y,Value: byte); ; Set a pixel in CharNo to Value, which can be 0 or 1. x & y are offsets ; into the character matrix which are based on resolutions of 8x8, 8x14, ; and 8x16. CharNo is in the range of 128 to 511. Value equ byte ptr [bp+4] y equ word ptr [bp+6] ; Treat as a word so it x equ byte ptr [bp+8] ; can be added quickly CharNo equ word ptr [bp+10] push bp mov bp,sp mov si,CharNo cmp si,128 jb ExitMP cmp si,511 ja ExitMP les di,Buffer sub si,128 mov al,Points xor ah,ah xor dx,dx mul si mov si,ax mov Temp2,ax and y,0ffh add si,y add di,si cmp Value,1 jz SetPixel mov cl,x mov bl,128 shr bl,cl not bl and es:[di],bl call SeeIfSpace jmp short ExitMP SetPixel: mov cl,x mov bl,128 shr bl,cl or es:[di],bl xor ax,ax ExitMP: pop bp ret 8 ModifyPixel endp GetChar proc near ; Calling sequence: GetChar(x,y: integer): integer; ; Given a coordinate, return the character at that coordinate. x & y ; are given as screen coordinates in the range of 640x200, 640x350, or ; 640x400 depending on the mode. The returned character is in the range ; of 0 to 511. y equ word ptr [bp+4] x equ word ptr [bp+6] push bp mov bp,sp mov ax,0b800h mov es,ax mov ax,y div Points xor ah,ah mov si,ax mov ax,80 xor dx,dx mul si mov si,x mov cl,3 shr si,cl add ax,si shl ax,1 mov si,ax mov ax,es:[si] and ah,8 shr ah,cl pop bp ret 4 GetChar endp Pset proc far ; Calling sequence: Pset(x,y: integer; Color: byte); ; Plot a point at x,y with the attribute in Color. Update the hardware ; font with the new information. Color equ byte ptr [bp+6] y equ word ptr [bp+8] x equ word ptr [bp+10] push bp mov bp,sp push x push y call GetChar cmp ax,128 jae InRang cmp TotalUsed,384 jb InRang2 jmp short ExitP1 InRang2: cmp Color,0 jz ExitP1 call GetNewChar InRang: cmp ax,0 jz ExitP1 push ax push x push y cmp Color,0 jz DoPush0 mov ax,1 push ax jmp short DidPush1 DoPush0: mov ax,0 push ax DidPush1: mov al,Color xor ah,ah push ax call WriteDot call WriteFont ExitP1: pop bp ret 6 Pset endp Pset2 proc near ; Calling sequence: Pset2(x,y: integer; Color: byte); ; Plot a point at x,y with the attribute in Color. Does not update the ; actual hardware font table (for use by higher-level routines). Color equ byte ptr [bp+4] y equ word ptr [bp+6] x equ word ptr [bp+8] push bp mov bp,sp push x push y call GetChar cmp ax,128 jae InRange cmp TotalUsed,384 jb InRange2 jmp short ExitP2 InRange2: cmp Color,0 jz ExitP2 call GetNewChar InRange: cmp ax,0 jz ExitP2 push ax push x push y cmp Color,0 jz Push0 mov ax,1 push ax jmp short Pushed1 Push0: mov ax,0 push ax Pushed1: mov al,Color xor ah,ah push ax call WriteDot ExitP2: pop bp ret 6 Pset2 endp MaskColors proc far ; Display the low-intensity character attributes only, disregarding the ; value specfied at bit 3 of the attribute bytes. Effective until ; the video mode is changed. mov ax,1000h mov bx,0712h int 10h ret MaskColors endp Freeze proc far ; Copies video memory to an alternate page and flips to that page. push ax push ds mov ax,40h ; Save CRT start & active page mov es,ax push word ptr es:[4eh] ; BIOS CRT_START push word ptr es:[62h] ; BIOS ACTIVE_PAGE mov ax,0b800h ; Segment of mode CO80 (3) mov es,ax mov ds,ax mov si,0 ; Source: This page mov di,2000h ; Destination: Page 2 mov cx,1000h ; Set to copy 2000h bytes cld ; Forward copy rep movsw ; Do the copy mov ax,0502h ; Function: Go to page 2 int 10h ; Switch the page mov ax,40h ; Restore CRT start & mov es,ax ; active page so that all pop word ptr es:[62h] ; BIOS functions take pop word ptr es:[4eh] ; place on "frozen," non- pop ds ; displayed page 0 pop ax ret Freeze endp Unfreeze proc far ; Flips back to page 0 to show what has been put there. mov ax,0500h ; Function: Display page 0 int 10h ; Call BIOS ret Unfreeze endp DoHlin proc near ; Designed for interface with Ellipse procedure. Call with the first ; (x,y) coordinate in CX,DX, and the amount to add (twice) in SI ; Color is in AX push ax push bx push cx push dx push si push di push cx push dx add cx,si add cx,si push cx push ax call Hlin2 pop di pop si pop dx pop cx pop bx pop ax ret DoHlin endp DoPset proc near ; For use with the Ellipse procedure as an interface to the main pixel-set ; routine, Pset2. x equ word ptr [bp+8] y equ word ptr [bp+6] Color equ byte ptr [bp+4] push bp mov bp,sp push ax push bx push cx push dx push si push di push es push x push y mov al,Color xor ah,ah push ax call Pset2 pop es pop di pop si pop dx pop cx pop bx pop ax pop bp ret 6 DoPset endp ; The following macro swaps n1 & n2 if n1>n2: SwapIfNeeded macro n1,n2 Local ExitSwap mov ax,n1 cmp ax,n2 jle ExitSwap xchg ax,n2 mov n1,ax ExitSwap: endm Hlin proc far ; Calling sequence: Hlin(x1,y1,x2: integer; Color: byte); ; Draws a horizontal line from x1,y1 to x2,y1 using the attribute ; specified in Color. Updates the hardware font table. Color equ byte ptr [bp+6] x2 equ word ptr [bp+8] y1 equ word ptr [bp+10] x1 equ word ptr [bp+12] push bp mov bp,sp SwapIfNeeded x1,x2 mov bx,x1 LoopHlin1: push bx push bx push y1 mov al,Color xor ah,ah push ax call Pset2 pop bx inc bx cmp bx,x2 jbe LoopHlin1 call WriteFont pop bp ret 8 Hlin endp Hlin2 proc near ; Calling sequence: Hlin2(x1,y1,x2: integer; Color: byte); ; Draws a horizontal line from x1,y1 to x2,y1 using the attribute ; specified in Color. The hardware font table is not updated. Color equ byte ptr [bp+4] x2 equ word ptr [bp+6] y1 equ word ptr [bp+8] x1 equ word ptr [bp+10] push bp mov bp,sp SwapIfNeeded x1,x2 mov bx,x1 LoopHlin2: push bx push bx push y1 mov al,Color xor ah,ah push ax call Pset2 pop bx inc bx cmp bx,x2 jbe LoopHlin2 pop bp ret 8 Hlin2 endp Vlin proc far ; Calling sequence: Vlin(x1,y1,y2: integer; Color: byte); ; Draws a vertical line from x1,y1 to x1,y2 using the attribute specified ; in Color. The hardware font table is updated. Color equ byte ptr [bp+6] y2 equ word ptr [bp+8] y1 equ word ptr [bp+10] x1 equ word ptr [bp+12] push bp mov bp,sp SwapIfNeeded y1,y2 mov bx,y1 LoopVlin: push bx push x1 push bx mov al,Color xor ah,ah push ax call Pset2 pop bx inc bx cmp bx,y2 jbe LoopVlin call WriteFont pop bp ret 8 Vlin endp Vlin2 proc near ; Calling sequence: Vlin(x1,y1,y2: integer; Color: byte); ; Draws a vertical line from x1,y1 to x1,y2 using the attribute ; specified in Color. The hardware font table is not updated. Color equ byte ptr [bp+4] y2 equ word ptr [bp+6] y1 equ word ptr [bp+8] x1 equ word ptr [bp+10] push bp mov bp,sp SwapIfNeeded y1,y2 mov bx,y1 LoopVlin2: push bx push x1 push bx mov al,Color xor ah,ah push ax call Pset2 pop bx inc bx cmp bx,y2 jbe LoopVlin2 pop bp ret 8 Vlin2 endp Box proc far ; Calling sequence: Box(x1,y1,x2,y2: integer; Color: byte); ; Draws a filled-in box with the attribute specified in Color. ; The upper-left coordinate is x1,y1. The lower right is x2,y2. Color equ byte ptr [bp+6] y2 equ word ptr [bp+8] x2 equ word ptr [bp+10] y1 equ word ptr [bp+12] x1 equ word ptr [bp+14] push bp mov bp,sp SwapIfNeeded x1,x2 SwapIfNeeded y1,y2 mov bx,y1 LoopBox: push bx push x1 push bx push x2 mov al,Color xor ah,ah push ax call Hlin2 pop bx inc bx cmp bx,y2 jbe LoopBox call WriteFont pop bp ret 10 Box endp OpenBox proc far ; Calling sequence: OpenBox(x1,y1,x2,y2: integer; Color: byte); ; Draws the outline of a box using the attribute specified in Color. ; The upper-left coordinate is x1,y1. The lower-right is x2,y2. Color equ byte ptr [bp+6] y2 equ word ptr [bp+8] x2 equ word ptr [bp+10] y1 equ word ptr [bp+12] x1 equ word ptr [bp+14] push bp mov bp,sp mov al,Color xor ah,ah push ax push x1 push y1 push x2 push ax call Hlin2 pop ax push ax push x1 push y2 push x2 push ax call Hlin2 pop ax push ax push x1 push y1 push y2 push ax call Vlin2 pop ax push ax push x2 push y1 push y2 push ax call Vlin2 pop ax call WriteFont pop bp ret 10 OpenBox endp Line proc far ; Calling sequence: Line(x1,y1,x2,y2: integer; Color: byte); ; Draws a line from x1,y1 to x2,y2 using the attribute specified in Color. ; Uses Bresenham's line algorithm. Actual code has been taken from ; a Plume/Waite book by Robert Lafore: Assembly language primer for the ; IBM PC & XT. Color equ word ptr [bp+6] y2 equ word ptr [bp+8] x2 equ word ptr [bp+10] y1 equ word ptr [bp+12] x1 equ word ptr [bp+14] push bp mov bp,sp mov ax,y2 sub ax,y1 mov si,1 jge store_y mov si,-1 neg ax store_y: mov delta_y,ax mov ax,x2 sub ax,x1 mov di,1 jge store_x mov di,-1 neg ax store_x: mov delta_x,ax mov ax,delta_x cmp ax,delta_y jl csteep call easy jmp finish csteep: call steep finish: call WriteFont pop bp ret 10 easy proc near mov ax,delta_x shr ax,1 mov halfx,ax mov cx,x1 mov dx,y1 mov bx,0 mov ax,delta_x mov count,ax newdot: push cx push dx push Color call DoPset add cx,di add bx,delta_y cmp bx,halfy jle dcount sub bx,delta_x add dx,si dcount: dec count jge newdot ret easy endp steep proc near mov ax,delta_y shr ax,1 mov halfy,ax mov cx,x1 mov dx,y1 mov bx,0 mov ax,delta_y mov count,ax newdot2: push cx push dx push Color call DoPset add dx,si add bx,delta_x cmp bx,halfy jle dcount2 sub bx,delta_y add cx,di dcount2: dec count jge newdot2 ret steep endp Line endp Ellipse proc far ; Call With: Ellipse(x1,y1,r1,r2: word; Color: byte); ; Draws an ellipse centered at x1,y1; the x-radius is in r1, and the ; y-radius is in r2. The attribute is specified in Color. ; Note: if bit 7 of the color is high, the entire ellipse if ; filled (and the bit is stripped). If it's low, just the ; perimeter is filled. ; The code has been taken from "EGA/VGA, A Programmer's Reference Guide" by ; Dyck Kliewer and published by Intertext/McGraw-Hill x1 equ word ptr [bp+14] y1 equ word ptr [bp+12] r1 equ word ptr [bp+10] r2 equ word ptr [bp+8] Color equ byte ptr [bp+6] ; r_l equ 1 t_b equ 11111110b pixpb equ 3 b_mask equ 10000000b push bp mov bp,sp and portion,t_b call e_call or portion,r_l push r2 push r1 pop r2 pop r1 call e_call call WriteFont pop bp ret 10 e_call proc near push ax push bx push cx push dx mov ax,x1 mov c_x,ax mov ax,y1 mov c_y,ax mov ax,0 mov xe,0 mov bx,r2 mov ye,bx mov cx,r1 call near ptr ellip pop dx pop cx pop bx pop ax ret e_call endp ellip proc near push bp mov Old_BP,bp mov si,ax mov ax,bx mul bx mov bp,dx mov bx,ax mov r2_lo,ax mov r2_hi,dx mov ax,cx mul cx mov di,dx mov cx,ax mov r1_lo,ax mov r1_hi,dx push bx push cx push di push bp push si mul ax mov bp,ax mov bx,dx mov ax,di mul cx shl ax,1 rcl dx,1 add bx,ax mov cx,dx mov ax,di mul ax add cx,ax mov ax,bp mov dx,r2_lo mov di,r2_hi add dx,r1_lo adc di,r1_hi mov bp,0 mov si,0 div_loop: cmp cx,0 jne c_div cmp bx,di ja c_div cmp ax,dx jae c_div jmp short div_done c_div: inc bp jnz no_of inc si no_of: sub ax,dx sbb bx,di sbb cx,0 jmp short div_loop div_done: shl ax,1 rcl bx,1 cmp di,bx ja no_up cmp dx,ax ja no_up inc bp jnz no_up inc si no_up: sub bx,bx cmp dx,0 jne rt_strt cmp si,0 jne rt_strt jmp rt_done rt_strt: mov bx,512 mov cx,512 rt_lp: shr cx,1 mov ax,bx mul ax cmp dx,si jg t_lg jl t_sm cmp ax,bp jb t_sm jmp short t_lg t_sm: add ax,bx adc dx,0 cmp si,dx ja t_sm2 cmp bp,ax ja t_sm2 jmp short rt_done t_sm2: add bx,cx jmp short rt_lp t_lg: sub ax,bx sbb dx,0 cmp dx,si ja t_lg2 cmp ax,bp ja t_lg2 jmp short rt_done t_lg2: sub bx,cx jmp short rt_lp rt_done: inc bx mov max_x,bx pop si pop bp pop di pop cx pop bx push bx push bp mov ax,cx mul ye mov bx,ax mov bp,dx mov ax,di mul ye add bp,ax neg bx not bp shl bx,1 rcl bp,1 add cx,bx adc di,bp mov t_e_lo,cx mov t_e_hi,di shl r1_lo,1 rcl r1_hi,1 shl r1_lo,1 rcl r1_hi,1 mov bx,ye dec bx mov ax,r1_lo mul bx mov bp,dx neg ax mov y_p_lo,ax mov ax,r1_hi mul bx add ax,bp not ax mov y_p_hi,ax pop bp pop bx shl bx,1 rcl bp,1 push bx push bp shl bx,1 rcl bp,1 mov r2_lo,bx mov r2_hi,bp mov cx,bx mov di,bp pop bp pop bx mov dx,t_e_hi mov ax,t_e_lo retest: ; Plot the points: push ax push bx push cx push dx push di push si push bp mov bp,Old_BP mov di,ye test portion,r_l jz no_xchg xchg si,di no_xchg: mov al,Color xor ah,ah test al,128 jnz DoHlinPlot mov cx,c_x add cx,si mov dx,c_y add dx,di push cx push dx push ax call DoPset sub cx,si sub cx,si push cx push dx push ax call DoPset sub dx,di sub dx,di push cx push dx push ax call DoPset add cx,si add cx,si push cx push dx push ax call DoPset jmp short DonePlot DoHlinPlot: and al,01111111b mov cx,c_x sub cx,si mov dx,c_y add dx,di call DoHlin sub dx,di sub dx,di call DoHlin DonePlot: pop bp pop si pop di pop dx pop cx pop bx pop ax cmp si,max_x jne e_cont jmp e_done e_cont: cmp dx,0 jl Less1 push bx push bp mov bx,y_p_lo mov bp,y_p_hi add ax,bx adc dx,bp dec ye add bx,r1_lo adc bp,r1_hi mov y_p_lo,bx mov y_p_hi,bp pop bp pop bx Less1: add ax,bx adc dx,bp inc si add bx,cx adc bp,di jmp Retest e_done: pop bp ret ellip endp Ellipse endp Code ends end