vga24_2.asm

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	jnc ld8
	inc dx
	push dx
	call vgablock
	pop dx
	jmp ld8
ld7:
;	dec di			; going left
	sub di,BytesPerPixel
	jnc ld8
	dec dx
	push dx
	call vgablock
	pop dx
ld8:
	cmp bx,0		; test d<0
	jge ld9
	add bx,[bp-14]		; d = d + incr1
	jmp ld11
ld9:
	add bx,[bp-16]		; d = d + incr2
	cmp word ptr [bp-12],0	; See if going up
	je ld10
	add di,ScanWidth	; Go to next line
	jnc ld11
	inc dx
	push dx
	call vgablock
	pop dx
	jmp ld11
ld10:
	sub di,ScanWidth	; Go to previous line
	jnc ld11
	dec dx
	push dx
	call vgablock
	pop dx
ld11:
	cmp BitsPerPixel,8      ; If 8bit continue else
	jne drwrgb2             ; call draw_rgb
	mov es:[di],al		; Write next pixel
	jmp ldd11
drwrgb2:
	push [bp+18]
	push [bp+16]
	push [bp+14]
	call draw_rgb
	add sp,6
ldd11:
	loop xloop
xloopend:
	jmp done


;
; Y oriented version of draw line. Slope must be outside -1 and 1 inclusive
;
yline:
	mov cx, [bp-12]		; cx has increment control

	mov ax, [bp-10]
	sal ax,1		; DX*2
	mov [bp-14],ax		; Save incr1
	sub ax,[bp-12]		; 2*dx - dy
	mov bx,ax		; bx has D value

	mov ax,[bp-10]		; Get DX
	sub ax,[bp-12]		; (DX-DY)
	sal ax,1		; 2*(DX-DY)
	mov [bp-16],ax		; Save incr2

	mov word ptr [bp-10],0  ; Assume going to left
	mov ax,[bp+8]		; Get x1
	sub ax,[bp+12]		; x1-x2
	jg ld12
	mov word ptr [bp-10],1	; Going to right
ld12:
	mov word ptr [bp-12],0	; Assume going up
	mov ax,[bp+6]		; Get y1
	sub ax,[bp+10]		; y1-y2
	jg ld13
	mov word ptr [bp-12],1	; Going down
ld13:

;
; Main Y oriented drawing loop.
;	ax = pixel value
;	bx = d
;	cx = loop control
;	dx = block number
;	di = block offset
;
	cmp BitsPerPixel,8      ; Is it 8bit mode
	jne drwrgb3             ;  no. call draw_rgb
	mov ax,[bp+14]
	mov es:[di],al		; Write first pixel
	jmp ldd13
drwrgb3:
	push [bp+18]
	push [bp+16]
	push [bp+14]
	call draw_rgb
	add sp,6
ldd13:	cmp cx,0		; Check if done
	je yloopend

yloop:
	cmp word ptr [bp-12],0	; See if going up?
	je ld14
	add di,ScanWidth	; going down
	jnc ld15
	inc dx
	push dx
	call vgablock
	pop dx
	jmp ld15
ld14:
	sub di,ScanWidth	; going up
	jnc ld15
	dec dx
	push dx
	call vgablock
	pop dx
ld15:
	cmp bx,0		; test d<0
	jge ld16
	add bx,[bp-14]		; d = d + incr1
	jmp ld18
ld16:
	add bx,[bp-16]		; d = d + incr2
	cmp word ptr [bp-10],0	; See if going left
	je ld17
;	inc di			; Go right
	add di,BytesPerPixel
	jnc ld18
	inc dx
	push dx
	call vgablock
	pop dx
	jmp ld18
ld17:
;	dec di			; Go left
	sub di,BytesPerPixel
	jnc ld18
	dec dx
	push dx
	call vgablock
	pop dx
ld18:
	cmp BitsPerPixel,8      ; Is it 8bit mode
	jne drwrgb4
	mov es:[di],al		; Write next pixel
	jmp ld18
drwrgb4:
	push [bp+18]
	push [bp+16]
	push [bp+14]
	call draw_rgb
	add sp,6
ldd18:
	loop yloop
yloopend:

;
; Clear stack and exit
;
done:
	add sp,8
	Postfix
vgaline endp



;
; Set colors from an array of rgb values.
;
; Parameters:
;	- Array of colors
;	- Start index
;	- Number of colors
;
public vgasetcolor
vgasetcolor proc far
	Prefix

	les dx,[bp+6]		; Get address of colormap
	mov bx,[bp+10]		; Get first color index
	mov cx,[bp+12]		; Get Number of indexes
	mov ax,1012h		; Set block of color registers function
	int 10h

	Postfix
vgasetcolor endp



;
; Fill a rectangular region with a given pixel value. Region is assumed to
; start on a even address and be an even width. Width and height values
; must be positive. Width and height values get modified.
;
; Parameters:
;	- Row for upper left corner
;	- Column for upper left corner
;	- Width of rectangle
;	- Height of rectangle
;	- Pixel value
;
; Locals
;	[bp-10] LineSkip
;
public vgafill
vgafill proc far
	Prefix
	sub sp,2
;
	mov	ax,vgadata	; Load address of data segment
	mov	ds,ax		; Set DS register

;
; Load window pointers
;
	mov ax,WinAddr
	mov es,ax		; Set ES to point to video memory

	push [bp+8]
	push [bp+6]
	call vgaoffset
	add sp,4
	mov di, ax		; Offset in di


;
; Setup control parameters for line draw.
;
	mov bx,ScanWidth        ; Get BytesPerScanLine
;
	push dx			; save for later
   ; added 1/2/92, djl, Adjust line offset value
	mov ax,[bp+10]          ; added to adjust for 15 16 or 24bit modes
	mul BytesPerPixel       ; columns times BytesPerPixel, djl

	sub bx,ax
   ;
	mov [bp-10], bx		; Amount to skip to get to next line

	mov ax,[bp+14]          ; Get 8bit pixel value
	mov ah,al		; ax has duplicated pixel value in al and ah
	pop dx
	even
linestart:
	mov cx,BlockEnd		; Last point in counter
	sub cx,di               ; cx has number of bytes till block change
				;
	mov bx,[bp+10]		; bx has number of bytes in line
	cmp BitsPerPixel,8      ; If 8bit mode skip counter adjustment, djl
	je lee1                 ; skip if 8bit, djl
	shl bx,1		; else multiply width of fill by two, djl
lee1:
	dec bx                  ;
	cmp bx,cx               ;
	ja le1
	mov cx,bx		; Wont need a block change
le1:
	sub bx,cx		; ax has number of words after block change
	inc cx
	ror cx,1
	ror bx,1
;
; Draw the line
;

	even
le4:
	cmp BitsPerPixel,8
	jne drwit
	cld
	rep stosw
	jmp lee4
drwit:
;	mov cx,[bp+10]
loopit:
	push [bp+18]
	push [bp+16]
	push [bp+14]
	call draw_rgb
	add sp,6
	add di,BytesPerPixel
	loop loopit
lee4:
	cmp di,0		; Check for exact alignment
	je le5
	cmp bx,0
	je le6

;
; Handle block change and continue
;
le5:
	inc dx
	push dx
	call vgablock
	pop dx

	cmp bx,0
	je le6

	mov cx,bx
	xor bx,bx
	xor di,di
	jmp le4

;
; Set up for next line
;
le6:
	dec word ptr [bp+12]
	je le7

	add di,[bp-10]		; Go to start of next line
	jnc linestart

	inc dx			; Bump block pointer
	push dx
	call vgablock
	pop dx
	jmp linestart

;
; Finish up
;
le7:
	add sp,2
	Postfix
vgafill endp


;
; Copy a given rectangle into display memory at the specified address.
; All pixels from the source rectangle are copied with no masking.
; Coordinates are assumed to be correct and wraparound accounted for by
; the calling routine. The start address and rectangle width are assumed
; to be even values to permit faster copy. The passed values may be modified
; and should not be retained by the calling routine.
;
; Parameters:
;	- Far pointer to source rectangle
;	- Total width of source memory
;	- Row for upper left corner
;	- Column for upper left corner
;	- Width of rectangle
;	- Height of rectangle
;
; Locals
;	[bp-10] LineSkip
;
public vgarect
vgarect proc far
	Prefix
	sub sp,2
;
	mov	ax,vgadata	; Load address of data segment
	mov	ds,ax		; Set DS register

;
; Load window pointers
;
	mov ax,WinAddr
	mov es,ax		; Set ES to point to video memory

	push [bp+14]
	push [bp+12]
	call vgaoffset
	add sp,4

;
; Setup control parameters for line draw.
;
	mov di, ax		; Offset for output memory in di

	mov bx,ScanWidth
	sub bx,[bp+16]
	mov [bp-10], bx		; Amount to skip to get to next line on output

	mov bx,[bp+10]
	sub bx,[bp+16]
	mov [bp+10], bx		; Amount to go to next line on input data

	mov si, [bp+6]		; Offset for input memory

	even
flinestart:
	mov cx,BlockEnd		; Last point in counter
	sub cx,di               ; cx has number of bytes till block change

	mov bx,[bp+16]		; bx has number of bytes in line
	dec bx

	cmp bx,cx
	ja lf1
	mov cx,bx		; Won't need a block change
lf1:
	sub bx,cx		; bx has number of words after block change
	inc cx
	ror cx,1
	ror bx,1


;
; Draw the line
;
	even
lf4:
	push ds			; Save segment for vgadata
	mov ax, [bp+8]
	mov ds,ax		; Set segment for source rectangle

	cld
	rep movsw

	pop ds			; Get segment for vgadata
	cmp di,0		; Check for exact alignment
	je lf5
	cmp bx,0
	je lf6

;
; Handle block change and continue
;
lf5:
	inc dx
	push dx
	call vgablock
	pop dx

	cmp bx,0
	je lf6

	mov cx,bx
	xor bx,bx
	xor di,di
	jmp lf4

;
; Set up for next line
;
lf6:
	dec word ptr [bp+18]
	je lf7

	add si,[bp+10]		; Goto next line in input
	add di,[bp-10]		; Go to start of next line on output
	jnc flinestart

	inc dx			; Bump block pointer
	push dx
	call vgablock
	pop dx
	jmp flinestart

;
; Finish up
;
lf7:
	add sp,2
	Postfix
vgarect endp


;
; Copy a given rectangle into display memory at the specified address.
; All pixels from the source rectangle are copied unless they have the
; value 0. Coordinates are assumed to be correct and wraparound accounted
; for by the calling routine. The passed values may be modified
; and should not be retained by the calling routine.
;
; Parameters:
;	- Far pointer to source rectangle
;	- Total width of source memory
;	- Row for upper left corner
;	- Column for upper left corner
;	- Width of rectangle
;	- Height of rectangle
;
; Locals
;	[bp-10] LineSkip
;
public vgarect2
vgarect2 proc far
	Prefix
	sub sp,2
;
	mov	ax,vgadata	; Load address of data segment
	mov	ds,ax		; Set DS register

;
; Load window pointers
;
	mov ax,WinAddr
	mov es,ax		; Set ES to point to video memory

	push [bp+14]
	push [bp+12]
	call vgaoffset
	add sp,4

;
; Setup control parameters for line draw.
;
	mov di, ax		; Offset for output memory in di

	mov bx,ScanWidth
	sub bx,[bp+16]
	mov [bp-10], bx		; Amount to skip to get to next line on output

	mov bx,[bp+10]
	sub bx,[bp+16]
	mov [bp+10], bx		; Amount to go to next line on input data

	mov si, [bp+6]		; Offset for input memory

	even
glinestart:
	mov cx,BlockEnd		; Last point in counter
	sub cx,di               ; cx has number of bytes till block change

	mov bx,[bp+16]		; bx has number of bytes in line
	dec bx

	cmp bx,cx
	ja lg1
	mov cx,bx		; Won't need a block change
lg1:
	sub bx,cx		; bx has number of bytes after block change
	inc cx

;
; Draw the line
;
	even
lg4:
	push ds			; Save segment for vgadata
	mov ax, [bp+8]
	mov ds,ax		; Set segment for source rectangle

	cld
lg8:	lodsb
	or al,al		; Test for 0
	jz lg9
	stosb
	jmp lg10
lg9:	inc di
lg10:	loop lg8

	pop ds			; Get segment for vgadata
	cmp di,0		; Check for exact alignment
	je lg5
	cmp bx,0
	je lg6

;
; Handle block change and continue
;
lg5:
	inc dx
	push dx
	call vgablock
	pop dx

	cmp bx,0
	je lg6

	mov cx,bx
	xor bx,bx
	xor di,di
	jmp lg4

;
; Set up for next line
;
lg6:
	dec word ptr [bp+18]
	je lg7

	add si,[bp+10]		; Goto next line in input
	add di,[bp-10]		; Go to start of next line on output
	jnc glinestart

	inc dx			; Bump block pointer
	push dx
	call vgablock
	pop dx
	jmp glinestart

;
; Finish up
;
lg7:
	add sp,2
	Postfix
vgarect2 endp



;
; Handle mouse and keyboard I/O
; If a keyboard key or mouse button is pressed, return a value indicating
; what was pressed. Also, maintain the mouse position values for external
; reference.
;
vgagetbutton proc far
	mov ah,0
	int 16h
	xor ah,ah               ; Don't want scan code
	ret
vgagetbutton endp



;
; Display a text string at a given location
;
; Parameters:
;	- row
;	- column
;	- character string
;	- pixel value for foreground
;
vgatext proc far
	ret
vgatext endp


vgacode	ends
	end