desperate help!!!

[MrPolite]

I've been working on this for 12 hours... I dont know why it doesnt work and my instructor hasnt been responding in the past 48hours... someone give me a little hint plz

INCLUDE irvine32.inc


.data
charArr BYTE 2 DUP(?)


.code
main PROC
; these just get two character inputs
	call ReadChar
	mov  charArr, al
	call ReadChar
	mov  [charArr+1], al
	
	
	; push the characters onto the stack
	push OFFSET [charArr + 1]
	push OFFSET charArr
	call swap
	
	
	
	mov  al, charArr
	call WriteChar
	mov  al, [charArr+1]
	call WriteChar
main ENDP



swap PROC
	push ebp
	mov  ebp, esp

	

	mov  al, BYTE PTR [ebp+8]
	mov  bl, BYTE PTR [ebp+12]
	mov	  [ebp+8],  bl
	mov	  [ebp+12], al
	
	
	pop  ebp
	ret 8	
swap ENDP 


END main

readChar and writeChar are provided in libraries... just read and write chars. uuh it's supposed to swap the two characters stores in the charArr but it doesnt do anything. what's wrong

[Peter Swinkels]

I don't know what assembler you are using but from what I can tell your program looks fine. Here is one suggestion though:
Perhaps you could use the XCHG (exchange (swap) instruction)?
Also what do you mean it does nothing? Does the pogram hang when executed or does it return the values that it supposed to swap without swapping them?

[MrPolite]

hehe yeah it would display the result without them being swapped... I wrote this afterwards... after turning it in haha. it works:

INCLUDE irvine32.inc

.data
charArr BYTE 2 DUP(?)

.code
main PROC
	; Get two character inputs and save them in a 2-byte array
	call ReadChar
	mov  charArr, al
	call ReadChar
	mov  [charArr+1], al
	
	
	; push the offsets of characters onto the stack
	mov eax, OFFSET charArr +1
	push eax					; second parameter
	dec  eax
	push eax					; first parameter
	
	call swap2
	
	
	mov  al, charArr
	call WriteChar
	mov  al, [charArr+1]
	call WriteChar
	
	exit
main ENDP


swap2 PROC
	push ebp			; save EBP
	mov ebp, esp
		
	mov eax, [ebp+8]	; offset of first parameter
						; EBP+8 is an offset. when dereferenced, it points
						; to the offset of the first array element (yeah, offset of an offset)
						; EAX has now the offset of the first array element
	;mov al, [eax]		; this would give the value of the first array element
	
	
	mov bl,	 [eax]		; Value of first parameter
	mov eax, [ebp+12]	; offset of second parameter
	xchg [eax],bl		; bl=val of second param. Second param is set to first param.
	mov eax, [ebp+8]	; offset of first param
	xchg [eax],bl		; first param is set to second param
	
	
	
	
	pop ebp				; restore EBP
	ret 8
swap2 ENDP
END main

[Darkwraith]

	; push the characters onto the stack
	push OFFSET [charArr + 1]
	push OFFSET charArr
	call swap

Methinks it was the fact that you should have either not have had brackets or had brackets (this fact changes from assembler to assembler.)