OSDev.org

Code: Select all

 ;**********************************;
 ; Simple load bmp demo             ;
 ; Assemble like this:              ;
 ; c:\fasm BmpDemo.asm BmpDemo.com  ;
 ;                                  ;
 ; By  Dex.                15/06/07 ;
 ;**********************************;
	org   100h	
	use16
start:
	mov	[LoadAddress],0 	   ; this is the offset of the top corner of image on screen.
					   ; So to put mario in middle of screem you would do this
					   ; mov     [LoadAddress],320*100+160
	mov	ax,0013h		   ; set video mode13h
	int	10h
	mov	ax,image		   ; move the address of our image into ax
	mov	[ImageBase],ax		   ; load ax into the var "ImageBase"
	call	DisplayBmp		   ; call the bmp display function.
	jc	error			   ; check for errors

	mov	ah,00h			   ; wait for key press.
	int	16h
error:
	mov	ax,0003h		   ; change to text mode
	int	10h
	ret				   ; return to dos

DisplayBmp:
	pusha				   ; save the regs
	push	ds
	push	es
	mov	si,[ImageBase]		   ; make sure si as the image address
	cmp	word [si+00h],4D42h	   ; test for 'BM' to make sure its a BMP file.
	jnz	BmpError		   ; if jump to exit with error
	mov	bx,[si+12h]		   ; start of header + 18 = width
	mov	bp,[si+16h]		   ; start of header + 22 = depth
	cmp	bx,320
	ja	BmpError
	cmp	bp,200
	ja	BmpError
	cmp	word [si+1Ch],8 	   ; start of header + 28 = bpp
	jnz	BmpError
	mov	si,0036h		   ;start of header + 54 = start of palette
	add	si,[ImageBase]
	mov	cx,256			   ;number of colors for patette
	mov	dx,03C8h
	mov	al,0
	out	dx,al
	inc	dx

SetPalete:
	mov	al,[si+2]		   ; red
	shr	al,2
	out	dx,al
	mov	al,[si+1]		   ; green
	shr	al,2
	out	dx,al
	mov	al,[si] 		   ; blue
	shr	al,2
	out	dx,al
	add	si,4
	loop	SetPalete

	push	0A000h
	pop	es
	lea	dx,[bx+3]		   ; round bmp width ;)
	and	dx,-4
	imul	di,bp,320
	add	di,[LoadAddress]	   ; this is the X Y offset of the screen
new_line:
	sub	di,320
	pusha
	mov	cx,bx
	rep	movsb
	popa
	add	si,dx
	dec	bp
	jnz	new_line
ExitOK:
	clc
	pop	es
	pop	ds
	popa
	ret

BmpError:
	stc
	pop	es
	pop	ds
	popa
	ret

 ;----------------------------------------------------;
 ; Data                                               ;
 ;----------------------------------------------------;
LoadAddress dw 0
ImageBase   dw 0
; you can include a bmp or file like this with fasm
; (NOTE: You can only use upto 64k with a com file).
image:
file 'mario.bmp'	; image1