Hi,

I am learning x86 Assembly language and found it interesting by following Youtube videos and some other tutorials. Of course I am going to by the most popular book of this language called: Art of Assembly

But I tried first to follow tutorials then by a book, that is my habit in learning languages

I tried to modifi a BMP file but each try results in an empty or incorrect formatted BMP file.

I am looking for a clue over and over but for 3 days I could not find what I am doing wrong

I am using MASM 6 for Windows 32bit.

Here is my ASM file:

		.586
		.model 		flat, stdcall
		option 		casemap :none
		include 	..\masm32\include\windows.inc
		include 	..\masm32\include\user32.inc
		include 	..\masm32\include\kernel32.inc
		include		..\masm32\macros\macros.asm
		include		..\masm32\include\masm32.inc

		includelib 	..\masm32\lib\user32.lib
		includelib 	..\masm32\lib\kernel32.lib
		includelib	..\masm32\lib\masm32.lib

		.data
FileName   	db 	"source.bmp", 0
filename	db	"result.bmp",0
errMsg 		BYTE 	"Cannot create file",0dh,0ah,0
	
hFile	 	HANDLE	?
hwFile		HANDLE	?

hMemory		HANDLE	?		;incoming data
pMemory		DWORD	?

hMemory_o	HANDLE	?		;outgoing data
pMemory_o	DWORD	?

ReadSize 	DWORD	?

bytesWritten	DWORD	?
firstLine	DWORD	?
FileSize	DWORD	?
BDoff		DWORD	?
BHSize		DWORD	?
szTemp		byte	16 dup (0)	;buffer for messages
szPrime		byte	"%08i", 0	;message format string
szPrimeH	byte	"%08lx",0	;message hexa format string
signature	DD	0
MEMORYSIZE  	equ	75535	;This is how much memory I'll allocate, 
				;so I will have a lot of space to store my file.
                ; I know this may seam stubid but I am learning Assemlby and do not
                ; want to face unneccessry bugs
im_offset	dd	?
im_width	dd	?
im_height	dd	?
bits_pix	dd	?




	.code
;................................
show	MACRO	caption, value
	print	SADD(caption)
	mov	eax, value
	invoke	wsprintf, offset szTemp, offset szPrime, eax	;converts eax into string
	print	offset szTemp					;print string
	print	SADD(13,10)	
	ENDM
;..................................

start:	

	invoke 		CreateFile, addr FileName,GENERIC_READ,FILE_SHARE_READ,NULL, OPEN_EXISTING,	FILE_ATTRIBUTE_NORMAL, NULL
	mov		 hFile, eax

;Allocate and lock the memory for incoming file.
	invoke 		GlobalAlloc, GMEM_MOVEABLE or GMEM_ZEROINIT, MEMORYSIZE
	mov 		hMemory, eax
	invoke 		GlobalLock, hMemory
	mov 		pMemory, eax

;Allocate and lock the memory for outgoing file.
	invoke 		GlobalAlloc, GMEM_MOVEABLE or GMEM_ZEROINIT, MEMORYSIZE
	mov 		hMemory_o, eax
	invoke 		GlobalLock, hMemory_o
	mov 		pMemory_o, eax


;Read file and save image parameters
	invoke 		ReadFile, hFile, pMemory, MEMORYSIZE-1, addr ReadSize, NULL
	mov		    esi, pMemory

	add		    esi, 02		;get filesize
	mov		    edi, [esi]
	invoke		wsprintf, offset szTemp, offset szPrime, edi
	print		offset szTemp
	print		SADD(10,13)
	
	add 		esi, 8		; jump 8 bytes to get image offset
	mov		    edi, [esi]	; get image offset
	mov 		im_offset,edi
	invoke		wsprintf, offset szTemp, offset szPrimeH, edi
	print		offset szTemp
	print		SADD(10,13)

	add		    esi,8		;jump 8 bytes to get image width
	mov		    edi, [esi]	; get image width		
	mov		    im_width, edi	
	invoke		wsprintf, offset szTemp, offset szPrime, edi
	print		offset szTemp
	print		SADD(10,13)

	add		    esi,4		;jump 4 bytes to get image height
	mov		    edi, [esi]	; get image height
	mov		    im_height, edi	
	invoke		wsprintf, offset szTemp, offset szPrime, edi
	print		offset szTemp
	print		SADD(10,13)

	add		    esi,4		;jump 4 bytes to get color plane
	mov		    ebx, [esi]	
	shr		    ebx,16		; get color plane and bit-pix
	print		SADD("bit-per-pix ")
	invoke		wsprintf, offset szTemp, offset szPrime, ebx
	print		offset szTemp
	print		SADD(10,13)

	mov		    ebp, pMemory	; get ready to start processing the image
	add		    ebp, im_offset	; esi now points to the first pix

;filtering process
;leave first row and first column and last row and last column untouched.

	mov		    esi,1		; esi is the row counter
	mov		    edi,1		; edi is the column counter


proc_pix:
	xor		    ebx,ebx		; ebx = 0 ebx will accumulate intermediate values for averaging
	mov		    eax, im_width	; eax is the pointer to the pixel
	mul		    esi
	add		    eax,edi		
	add		    ebx, [ebp+eax]	;get the pixel(I,J) 

	mov		    eax, im_width
	add		    esi,1		;next row (I+1)
	mul		    esi
	add		    eax,edi		
	add		    ebx, [ebp+eax]	;get the pixel(I+1,J) 


	mov		    eax, im_width
	sub		    esi,2		; prev row (I-1)
	mul		    esi
	add		    eax,edi		
	add		    ebx, [ebp+eax]	;get the pixel(I-1,J) 

	add		    esi,1		;back to the current row

	add		    edi,1		;get next column (J+1)
	mov		    eax, im_width
	mul		    esi
	add		    eax,edi		
	add		    ebx, [ebp+eax]	;get the pixel(I,J+1) 


	sub		    edi,2		; get prev column (J-1)
	mov		    eax, im_width
	mul		    esi
	add		    eax,edi		
	add		    ebx, [ebp+eax]	;get the pixel(I,J-1) 

	add		    edi,1		;back current column
	xor		    edx, edx	;clear upper part dividend
	mov		    eax, ebx	;move data to eax to divide
	mov		    ecx, 5	
	div		    ecx		    ;do the average (div 5)>>> result in eax
    

	inc		edi		    ; do the next column
	cmp		edi, im_width	
	jl		proc_pix

	inc 		esi		; do the next row
	mov		edi,1		; skip the first column	
	cmp		esi, im_height	
	jl		proc_pix

;....................................................................................


new_file: 
	invoke 		CreateFile,ADDR filename, GENERIC_WRITE, NULL, NULL,CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0
	mov 		hwFile,eax		; save file handle

; handling of error if invalid file handle
	cmp 		eax,INVALID_HANDLE_VALUE
	jne		writef
	invoke		StdOut, addr errMsg	; Display error message
	jmp  		QuitNow
	
writef:	invoke 		WriteFile, hwFile, pMemory_o, FileSize, ADDR bytesWritten, 0		


QuitNow:
	invoke		GlobalUnlock, pMemory
	invoke		GlobalUnlock, pMemory_o
	invoke		GlobalFree, hMemory
	invoke		CloseHandle, hFile
	invoke		CloseHandle, hwFile
	invoke		ExitProcess, NULL
	end 		start
;finish

 

By the way I am using the popular "Lena" bitmap