ScanMap	proc
 
	; EBX = Pointer to default procedure if window has been sub/super classed.
	; ECX = Number of handlers in map (can be NULL, although not usual).
 
		lodsd				; Get address of default window procedure.
		mov	ebx, eax		; Save in case window has been sub/super classed
		lodsw				; Number of messages in map
		cwde				; Sign extend to 32 bits, can be NULL but not usually the case
 
		.if	eax				; Does map have defninitions
			mov	ecx, eax		; Move into counter register
 
		; Cycle through each of the application defined handlers until a match is found,
		; otherwise just automatically drop into default message processing.
 
		@@:	lodsw				; Get message number from map
			mov	edx, eax		; Copy it so next instruction doesn't destroy
			lodsd				; Pointer to application defined handler
 
			.if	dx == [esp + 8]		; When match if found, execute handler
				lea	esi, [esp + 4]		; ESI points to API parameters
				call	eax			; Call handler
				jnc	@F			; Do default processing if no carry
 
				xor	eax, eax		; Set default return condition
				ret	16			; Clean-up stack and return.
			.endif
 
			loopnz	@B			; Keep comparing until ECX = Zero.
		.endif
 
	@@:	; Either there wasn't a need to handle this event or the handler requires default processing
 
		.if 	!ebx
			jmp	DefWindowProc	; Do default processing for this window
		.endif
 
	; Processing of a subclassed window requires address of default code so it will
	; be placed on stack at this point.
 
		xchg	[esp], ebx		; Exchange default processing address
		push	ebx			; with return and push on stack again
		jmp	CallWindowProc	; Do default processing for this window