source click
Tanenbaum [1987] Operating Systems
mov ax,24(bp)
mov si,22(bp)
mov cx,*4
L2: rcr ax,*1
rcr si,*1
loop L2
mov ds,si
ax = high-order word of 32-bit source
si = low-order word of 32-bit source
start extracting click number from source
click number is source address / 16
it is used in segment register for copy
4 bits of high-order word are used
ds = source click