A85: Re: Re: Assembly-85 Digest V1 #491
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A85: Re: Re: Assembly-85 Digest V1 #491
For all vars on the calc the VAT has an entry containing the name, type and
a pointer to the data. So to to find a specific var you go through all vat
entried looking for one with the right name and the right type. Once you
have found that you can use the pointer to access the data.
What shells does is that they search the vat for a var of the right type,
and if they find one they use the data pointer to check the first 3 bytes of
the variable. These bytes are always set to some specific value, which is
how valid asm programs are recognized. For example, in Ash the header is D9
00 30, so what Ash does is it searches for vars of the right type, and when
it finds one it check that the first three bytes corresponds to this. This
is also how shells can tell the difference between asm programs written for
different shell.
Using vars on the ti8xs can seem hard at first, but it is actually not that
bad. I was working on a document explaining all this (and a few other things
such as OPs and FP Stack), but I have never finished it. To my knowledge
there is no toturial or anything like that out there which explains how to
use vars.
Dines
----- Original Message -----
From: <MalcolmJ1@aol.com>
To: <assembly-85@towerguard.unix.edu.sollentuna.se>
Sent: Wednesday, February 17, 1999 11:29 AM
Subject: A85: Re: Assembly-85 Digest V1 #491
>
>how to you get stuff in the vat like variables. i'm wondering how, say,
>usgard searches the vat for any strings that are usgard type and them
displays
>them. how does it know if it's a usgard varialble, how does usgard
actually
>search, and where does it store the information to be displayed? i've
already
>read varstor.txt in the archives section on how they are stored. but it's
not
>that understandable. is there a tutorial out there that someone knows
about?
>
>jimi
>