Lookup Table in assembly

Kevin L.

I'm looking for a simple example in assembly to do a lookup table.

DAT          org
 
          
'--------- How do I access the table below?
 
          mov     ptr, #2   'Get second item in table
          call    look
 
 

look
 
          ????
          mov     data, ????
          and     data, $FFFF
look_ret  ret
 
 
data      res     1
ptr       res     1
 
table     word    $0000
          word    $C0C1
          word    $C181
          word    $0140
          word    $C301
          word    $03C0
          word    $0280
' Many more values

Mike Green

Here's an example:

look       mov    temp,ptr
           add    temp,#table    ' input value in ptr (0 to n-1)
           movs   :inline,temp   ' have to use instruction modification
           nop                   ' need pause here for future pipelining
:inline    mov    data,0-0       ' get long value from table
           test   ptr,#1   wz    ' do we want odd or even half
    if_z   and    data,mask      ' if even, take lower 16 bits
    if_nz  shr    data,#16       ' if odd, take upper 16 bits
look_ret   ret
mask       long   $FFFF

You can do the same kind of thing if you need byte values.

Post Edited (Mike Green) : 8/21/2006 10:54:54 PM GMT

Kevin L.

Thanks Mike!

Harley

It is a shame that some answers to questions are not visible for all of us.

I, for one, would appreciate seeing the answer to Kevin's question of

Kevin L. said...
I'm looking for a simple example in assembly to do a lookup table.

The answer not being posted isn't very helpful to others who may also learn from this message string.

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Harley Shanko
h.a.s. designn

Mike Green

What happens when you try to see the answer? I'm not aware of any restrictions on the viewing of message threads, only that you have to be a registered member to post a reply. Maybe you looked for it while I was correcting a mistake around 10:55 GMT. Does it appear now? I'd be happy to repost it.