Output of file : DIFFSET.ASM contained in archive : RHSTDLIB.ZIP

stdlib segment para public 'slcode'
assume cs:stdlib
; difference- Computes the difference of one set with another.
; inputs:
; ES:DI- Points at the destination set (at its mask byte).
; DX:SI- Points at the mask byte of the source set.
public sl_difference
sl_difference proc far
push ds
push ax
push cx
push si
push di
mov ds, dx
mov al, es:[di] ;Get mask bytes
not al
mov ah, [si]
add si, 8 ;Skip to start of set
add di, 8
mov cx, 256
DifLp: test ah, [si]
jz Next
and es:[di], al
Next: inc si
inc di
loop DifLp
pop di
pop si
pop cx
pop ax
pop ds
sl_difference endp
stdlib ends