Am 23.03.2015 um 19:23 schrieb John McKown:
On Mon, Mar 23, 2015 at 1:06 PM, John Ehrman <[email protected]> wrote:
Paul Gilmartin noted...
IMO, HLASM syntax is the most god-awful piece of clap-trap garbage I
have
ever laid my eyes on. Well, perhaps a close second to JCL.
HLASM's syntax is a direct descendant of the assembler languages for a
great variety of earlier systems, including the IBM 650, 704, 709(x),
System/360 etc. The one novelty in the System/360 assembler language was
the introduction of a separate, distinct class of variable symbols;
previous assemblers used ordinary symbols as macro variable symbols. At
the time the 360 was being developed, there were no low-level high-level
languages (PL/S and C came years later); what else was available for
building systems? And you'd be truly repelled by the language used on the
early IAS machines; by comparison, HLASM's is a model of simplicity and
clarity.
I'm not defending historical clap-trap, but perhaps we're living too close
to the present?
I know that I need to watch myself on that score. There is a big
problem with the desire to advance versus the desire to continue to
use what already works. As an example, look at some of the posts in
IBM-MAIN about COBOL 5 requiring that the executable be in a PDSE and
impossible to run from a PDS. Lots of people yelling like somebody ran
over their pet dog. But, at the same time, others are yelling for 64
bit AMODE. Can't win for losing. I sometimes get that myself: "You can
change anything you need to. So long as it does not impact anything."
Huh? Not just "negatively impact", but make any change that might be
noticed and complained about by _anybody_. So I play with z/OS UNIX
because I'm the only user. And I still cuss myself out. [grin].
The only enhancement that I, personally, would like would be for "free
format" input into HLASM with _no_ line limits. Mainly because I keep
my HLASM source in a UNIX file and, depending on "things", I use the
"as" UNIX command to assemble it. I'm a bit of a UNIX partisan for
"interactives". Being forced to use column alignment when I use a
non-ISPF editor is a royal bother. Hum, it would also be nice if the
tab character were a white space character outside of literals.
There was an old ASSEMBLER on an old German mainframe computer in the
1970s (not IBM compatible) that had free form input. Because commas were
not part of the syntax, they could be used as instructions separators.
For IBM
ASSEMBLER, the comma is already used, but semicolon is still free, that is:
it should or could be possible to write multiple instructions in one line
and seperate them with semicolons; instructions without a label could
start with
a blank. Or: with the old Telefunken ASSEMBLER, every label was terminated
by a = character, so the labels were recognized and distinguished from
opcodes
this way. This looked nice, IMO.
Using ; as separator and = for the labels, a loop in IBM ASSEMBLER could be
written like this:
LA R5,10;LA R6,TAB;
LOOP=CLC 0(10,R6),TABX;JE FOUND;LA R6,10(R6);BCT R5,LOOP;
NOTFOUND=...;
FOUND=...;
...
TABX=DC CL10'SEARCHARG'
TAB=10DS CL10
Of course, in the listing, the instructions should be printed on
separate lines
(together with the resulting opcodes etc.); this is what the Telefunken
ASSEMBLER did.
With this syntax, you may insert blanks whereever you like; the label
can be recognized
anyway (it has the = char at the end). For the start of the comment
field there has to
be another solution, for example, # like other ASSEMBLERs do or //
borrowed from C or C++.
Even /* ... */ would be possible.
This would work IMO ... but I'm not sure if the ASSEMBLER programmers
really would
like - and use - it.
Kind regards
Bernd
John Ehrman
