24 bit BMP writing code

[enhzflep]

Just finished some code for another site I visit. It's just been hacked together very quickly, though perhaps somebody will get some use from it. With error checking on the 4 calls to CreateFile or WriteFile you'd have an okay function.

Shown below is the output from the code.

Tootles...

.586
 .MODEL flat, stdcall OPTION CASEMAP:NONE  ;Case sensitive Include windows.inc
 Include kernel32.inc
 Include masm32.inc IncludeLib kernel32.lib
 IncludeLib masm32.lib myMain	PROTO
 writeBmp24 PROTO :DWORD,:DWORD,:DWORD,:DWORD .DATA?
	 pixelData	dd	?   ; pointer to the pixel buffer
	 x	dd ?		   ; used to create the pattern
	 y	dd ?	 myBmpInfo		BITMAPINFO	<>
	 myInfoSize		dd	?
	 fileHeader		BITMAPFILEHEADER	<>
	 outputFileHandle	dd	?	 fileHandle		dd	?
	 retVal			dd	? .DATA
	 filenameStr DB "enhzflep.bmp", 0
	 bmpWidth equ 128
	 bmpHeight equ 128 .CODE Start:
   Invoke myMain
   Invoke ExitProcess,0
 myMain Proc
	; allocate mem for our pixel buffer
	 invoke GlobalAlloc, GMEM_FIXED, bmpWidth*bmpHeight*3
	 mov pixelData, eax	; make sure it's been cleared first
	 invoke RtlZeroMemory, eax,bmpWidth*bmpHeight*3	; go through, make the array a simple XOR pattern.
	 mov	ebx, pixelData
	 mov	y, 0
	 .while y < bmpHeight
		 mov	x, 0
		 .while x < bmpWidth
			 mov	eax, x
			 xor	eax, y
			 mov	byte ptr [ebx], 0
			 inc ebx
			 mov	byte ptr [ebx], 0
			 inc ebx
			 mov	[ebx], al
			 inc ebx
			 inc x
		 .endw
		 inc y
	 .endw	; write the bugger to disk
	 Invoke writeBmp24, bmpWidth, bmpHeight, addr filenameStr, pixelData	; give back the memory
	 invoke GlobalFree, pixelData	 Ret
 myMain endp
; writes a 24 bit bmp file
; call with width, height, pointer to filename, pointer to width*height*3 bytes of pixelData
 writeBmp24 proc, myWidth:DWORD, myHeight:DWORD, myFilename:DWORD, pixBuffer:DWORD
	; size of header for 24 bit images
	 mov	myInfoSize, sizeof BITMAPINFOHEADER	; magic file signature
	 mov	fileHeader.bfType, 04d42h	; unused, must be zero
	 mov fileHeader.bfReserved1, 0
	 mov fileHeader.bfReserved2, 0	; offset in file of start of pixel data
	 mov	eax, sizeof BITMAPFILEHEADER
	 add	eax, myInfoSize
	 mov	fileHeader.bfOffBits, eax	; total size of file
	 mov	ebx, sizeof BITMAPFILEHEADER
	 add	ebx, myInfoSize
	 mov	edx, myWidth
	 imul	edx, myHeight
	 push edx
	 add	ebx, edx
	 shl	edx, 1
	 add	ebx, edx
	 mov fileHeader.bfSize, ebx	; size of header
	 mov	myBmpInfo.bmiHeader.biSize, sizeof myBmpInfo.bmiHeader	; biSizeImage = width*height*3
	 mov myBmpInfo.bmiHeader.biSizeImage, edx
	 pop	edx
	 add  myBmpInfo.bmiHeader.biSizeImage, edx	; image dimensions
	 mov	eax, myWidth
	 mov	myBmpInfo.bmiHeader.biWidth, eax
	 mov	eax, myHeight
	 mov	myBmpInfo.bmiHeader.biHeight, eax	; pixels per meter
	 mov	myBmpInfo.bmiHeader.biXPelsPerMeter, 2835
	 mov	myBmpInfo.bmiHeader.biYPelsPerMeter, 2835	; 1 color plane, 24 bits per pixel
	 mov myBmpInfo.bmiHeader.biPlanes, 1
	 mov myBmpInfo.bmiHeader.biBitCount, 24	; uncompressed, 24 bit image
	 mov myBmpInfo.bmiHeader.biCompression, 0	; unused for true color images - only used with images that have a palette
	 mov myBmpInfo.bmiHeader.biClrImportant, 0
	 mov myBmpInfo.bmiHeader.biClrUsed, 0	; open file for writing - truncate to zero length if it already exists
	 invoke CreateFile, myFilename, GENERIC_WRITE, 0, 0, CREATE_ALWAYS, FILE_ATTRIBUTE_ARCHIVE, 0  
	 mov	fileHandle, eax	; write the file header
	 invoke WriteFile, fileHandle, addr fileHeader, sizeof BITMAPFILEHEADER, addr retVal, 0
	; write the info header
	 invoke WriteFile, fileHandle, addr myBmpInfo, myInfoSize, addr retVal, 0
	; write the pixel data
	 invoke WriteFile, fileHandle, pixBuffer, myBmpInfo.bmiHeader.biSizeImage, addr retVal, 0	; close the file
	 invoke CloseHandle, fileHandle	 Ret
 writeBmp24 endp End Start

[diablo2oo2]

nice piece of code. could be usefull one day

[Gushe]

I just read trough this because I'd like to learn ASM, and I must say that it's nice commented (not too much, but clear:))

Thanks!