Re: Book on Assembly


santosh wrote:
randyhyde@xxxxxxxxxxxxx wrote:
Jim Carlock wrote:
<randyhyde@xxxxxxxxxxxxx> wrote:
[BIG snip]

You've often mentioned in the past that students taking an assembly
language/machine organisation course, do so after a course on a high
level langauge. If so, why is it necessary to teach them flow control
constructs like IF, WHILE, FOR etc., again? They would've learned the
semantics of these and more in the previous HLL course.

You're not teaching them the *semantics* of these instructions, you're
teaching them how to implement them in assembly language. Big
difference. The bottom line is that they already know how to *think* in
terms of statements like IF, WHILE, etc. They *don't* know how to think
in terms of CMP and Jcc. So you teach them how to implement the stuff
they already know (IF, WHILE, etc.) using CMP and Jcc and they're up
and running *really* fast.



Would it not be more time efficient to teach them the native
conditional branching instructions and tell them to implement the HLL
control statements with them as intermediate level assignments?

???
This is exactly what is done (or, at least, what I do). I'm not sure I
follow what you're trying to say. Obviously, in order to implement
HLL-like control structures with CMP and Jcc, you must first teach them
the semantics of the CMP and Jcc instructions. The next step, before
you let them write a whole lot of code, is to tell them how to use
those CMP and Jcc instructions to simulate an IF statement, or a WHILE
loop, or...



If you've already answered to this question just point me to the post.
I haven't been keeping a close track of this group lately.

Probably what you missed was the original point, which is that students
should *not* be taught about simulating IF/WHILE/etc, that they should
just use the CMP/Jcc paradigm in whatever way comes natural to them
(i.e., arbitrary control structures). I've seen this in action, it is a
disaster.
Cheers,
Randy Hyde

.

Relevant Pages

  • Re: Book on Assembly
    ... HLL-like control structures with CMP and Jcc, ... The students already know HLL-like control structures. ...
    (alt.lang.asm)
  • Re: migrating nasm code to to x86_64
    ... fit into a Jcc short <Imm8>, as the code has become a tad bloated ... Look closely at the Jcc instructions. ...
    (alt.lang.asm)