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Power-Programmierung
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1990
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05
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vgacolor.asm
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Assembly Source File
|
1990-08-06
|
5KB
|
181 lines
;
; *** Listing 1 ***
;
; Program to demonstrate use of the DAC registers by selecting a
; smoothly contiguous set of 256 colors, then filling the screen
; with concentric diamonds in all 256 colors so that they blend
; into one another to form a continuum of color.
;
.model small
.stack 200h
.data
; Table used to set all 256 DAC entries.
;
; Table format:
; Byte 0: DAC register 0 red value
; Byte 1: DAC register 0 green value
; Byte 2: DAC register 0 blue value
; Byte 3: DAC register 1 red value
; Byte 4: DAC register 1 green value
; Byte 5: DAC register 1 blue value
; :
; Byte 765: DAC register 255 red value
; Byte 766: DAC register 255 green value
; Byte 767: DAC register 255 blue value
ColorTable label byte
; The first 64 entries are increasingly dim pure green.
X=0
REPT 64
db 0,63-X,0
X=X+1
ENDM
; The next 64 entries are increasingly strong pure blue.
X=0
REPT 64
db 0,0,X
X=X+1
ENDM
; The next 64 entries fade through violet to red.
X=0
REPT 64
db X,0,63-X
X=X+1
ENDM
; The last 64 entries are increasingly dim pure red.
X=0
REPT 64
db 63-X,0,0
X=X+1
ENDM
.code
Start:
mov ax,0013h ;AH=0 selects set mode function,
; AL=13h selects 320x200 256-color
int 10h ; mode
;load the DAC registers with the
; color settings
mov ax,@data ;point ES to the default
mov es,ax ; data segment
mov dx,offset ColorTable
;point ES:DX to the start of the
; block of RGB three-byte values
; to load into the DAC registers
mov ax,1012h ;AH=10h selects set color function,
; AL=12h selects set block of DAC
; registers subfunction
sub bx,bx ;load the block of registers
; starting at DAC register #0
mov cx,100h ;set all 256 registers
int 10h ;load the DAC registers
;now fill the screen with
; concentric diamonds in all 256
; color attributes
mov ax,0a000h ;point DS to the display memory
mov ds,ax ; segment
;
;draw diagonal lines in the upper
; left quarter of the screen
mov al,2 ;start with color attribute #2
mov ah,-1 ;cycle down through the colors
mov bx,320 ;draw top to bottom (distance from
; one line to the next)
mov dx,160 ;width of rectangle
mov si,100 ;height of rectangle
sub di,di ;start at (0,0)
mov bp,1 ;draw left to right (distance from
; one column to the next)
call FillBlock ;draw it
;
;draw diagonal lines in the upper
; right quarter of the screen
mov al,2 ;start with color attribute #2
mov ah,-1 ;cycle down through the colors
mov bx,320 ;draw top to bottom (distance from
; one line to the next)
mov dx,160 ;width of rectangle
mov si,100 ;height of rectangle
mov di,319 ;start at (319,0)
mov bp,-1 ;draw right to left (distance from
; one column to the next)
call FillBlock ;draw it
;draw diagonal lines in the lower
; left quarter of the screen
mov al,2 ;start with color attribute #2
mov ah,-1 ;cycle down through the colors
mov bx,-320 ;draw bottom to top (distance from
; one line to the next)
mov dx,160 ;width of rectangle
mov si,100 ;height of rectangle
mov di,199*320 ;start at (0,199)
mov bp,1 ;draw left to right (distance from
; one column to the next)
call FillBlock ;draw it
;
;draw diagonal lines in the lower
; right quarter of the screen
mov al,2 ;start with color attribute #2
mov ah,-1 ;cycle down through the colors
mov bx,-320 ;draw bottom to top (distance from
; one line to the next)
mov dx,160 ;width of rectangle
mov si,100 ;height of rectangle
mov di,199*320+319 ;start at (319,199)
mov bp,-1 ;draw right to left (distance from
; one column to the next)
call FillBlock ;draw it
mov ah,1 ;wait for a key
int 21h ;
mov ax,0003h ;return to text mode
int 10h ;
mov ah,4ch ;done--return to DOS
int 21h
; Fills the specified rectangular area of the screen with diagonal
; lines.
;
; Input:
; AL = initial attribute with which to draw
; AH = amount by which to advance the attribute from
; one pixel to the next
; BX = distance to advance from one pixel to the next
; DX = width of rectangle to fill
; SI = height of rectangle to fill
; DS:DN = screen address of first pixel to draw
; BP = offset from the start of one column to the start of
; the next
FillBlock:
FillHorzLoop:
push di ;preserve pointer to top of column
push ax ;preserve initial attribute
mov cx,si ;column height
FillVertLoop:
mov [di],al ;set the pixel
add di,bx ;point to the next row in the column
add al,ah ;advance the attribute
loop FillVertLoop ;
pop ax ;restore initial attribute
add al,ah ;advance to the next attribute to
; start the next column
pop di ;retrieve pointer to top of column
add di,bp ;point to next column
dec dx ;have we done all columns?
jnz FillHorzLoop ;no, do the next column
ret ;
end Start