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From: porky_pig_jr AT my-deja DOT com (Porky Pig Jr)
Newsgroups: comp.os.msdos.djgpp
Subject: question on AT&T assembly question (creating template for local variables offsets)
Date: 19 Jan 2004 13:41:37 -0800
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To: djgpp AT delorie DOT com
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Hello,

trying to learn AT&T assembly language syntax, and intel ia-32
environment. have a decent IBM/370 Assembly language background. Went
through several examples of code. There is one thing I'm missing:
create templates for dynamic (or local) variables. In IBM/370 there is
a thing called 'dummy section' or dsect. This section does not take
any space, its only purpose is to allow you to define the labels of
dynamic variables. You declare them just as if they were real static
variables. Once you establish you base register for some storage, you
can use the labels from dummy section as the offsets of base register.

What I saw in examples for AT&T (or GAS) is just the whole bunch of
equates, something like this:

.equ VAR1 0   /* VAR1 is .long */
.equ VAR2 4   /* VAR2 is .int */
.equ VAR3 6    ...

and then you can refer to them as VAR1(%bsp), VAR1(%bsp),

etc. That is, we have to keep track of the sizes of the variables. In
IBM/370 dsect it's a bit more convenient and the coding is roughly
like this (using the pseudo-GAS syntax):

DUMMY:
.dsect
VAR1:
.long 
VAR2:
.long
VAR3:
.int
.equ varsize . - DUMMY

(follows by another dummy section, or 'control section' which is a mix
of .data and .text in IBM/370 lingo).


So we don't have to compute anything. We just pretend those are static
variables. Assembler does it for us. Much better than '.equ'.

Went through GAS manual, but it was not obvious how can I create an
equivalent code. Would appreciate some hints/suggestions/examples/...

TIA.