[Coco] Linville's ramblings on assembly vs machine code

James Jones jejones3141 at gmail.com
Mon Jul 10 15:59:37 EDT 2017


That's what disassemblers are for, save for programs that do tricks like
modifying themselves.

Were I teaching assembly language, I'd show the instruction formats, and
then go into particular instructions as needed. Are you wondering whether
the order of registers in the push/pull instructions makes a difference?
Write assembly language that has them in different orders, and see whether
the generated bytes for the two instructions as shown in the listing are
the same. (If memory serves, they are.) About span-dependent instructions,
I'd point out the different encodings and point interested students at the
relevant paper from CACM back in the 70s, (The general problem is
NP-complete, but there's an efficient algorithm that works for a family of
displacements that includes all but the most pathological examples, and a
good assembler ought to implement it.)

James

On Mon, Jul 10, 2017 at 12:38 PM, CoCo Demus <retrocanada76 at gmail.com>
wrote:

> Machine language is mandatory when you are debugging or disassembling code
>
>


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