Re: Variable length addresses

[Howard C Berkowitz <[e-mail]>]

Back in the prehistoric days when we had to pick the faster instructions
when coding _application_ programs, I found it useful to avoid true
variable length records.  My alternative to full generality (i.e.,
a length-in-bytes field) was to use a bit string with a bit turned
on whenever an optional field WAS present.  

I then used the bit string, either directly or more commonly through
an indirect table, to jump to routines that processed that set of
elements (or called a sequence of routines for each field).

I wonder if the variable-vs.-fixed <thingie>* discussion might use
some of these ideas.  While an overall <thingie> is indeed of variable
length, I suggest that it usually will contain a sequence of
fixed-length elements.  The presence or absence of these elements
is carried in a bit string rather than a total length counter.

I could see a pipelined processor architecture where processing is
started on elements as soon as their flag is recognized.  Hmmm...
on
thinking about this further, it's more of a pipelined decoder
coupled with parallel element subprocessors.

---
Howard