x86 question about bit comparisons

sub 	AX,AX
sub		SI,SI
mov		bx,[bp+6]		;get message offset

@@mainLoop:
	mov		cx,8
	mov		dh,80h
	cmp		byte ptr [bx + si],0
	je		@@endChecker
@@innerLoop:
	test	byte ptr [bx + si],dh
	jz		@@zeroFound
	inc		AX
	@@zeroFound:
		shr		bh,1
		loop	@@innerLoop
	@@continue:
		inc		si
		jmp		@@mainLoop

mov    cx, 8
        mov    dh, byte ptr [bx+si]
@@innerLoop:
        add    dh, dh
        adc    ax, 0
        loop   @@innerLoop