[BLACKBOX] Ofront supporting for unsigned types

From: Oleg N. Cher <"Oleg>
Date: Wed, 25 Apr 2012 21:29:14 +0300

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Dear Norayr,

You wrote in your nmos6502-oo2c's README:

"this work is based on the Stewart Greenhill's port of oo2c for avr
microcontrollers
He prepared patches for oo2c to produce c code for 8 bit machines, and a
small mini library."

What is sort of this patch? Is there a possibility to use unsigned data
types?

Mr. Josef Templ wrote me: "As far as I know, there is no simple way to
support new types without significantly extending the compiler incl. the
symbol file format and the code generator. This may get messy."

And he is absolutely right. I'm in doubts about the hidden problems of
addition of the unsigned types. This concept as is already generates
many of questions. Let to mix signed and unsigned types (as in C) or
disallow (as in Modula-2)? What to do with casting the types? Must be
only in-SYSTEM solution for the casting, or end-user? I am afraid
that this will be not improvement, but a hack. And I'm interested
in looking of available decisions of the similar problem.

You certainly know that for such weak CPU as 6502 (or Z80) unsigned
arithmetic is not luxury, but absolute necessary. Every C developers
says me: "For loop with counter from 0 to 255 I've used in C one-byte
variable, and you in Oberon must use two-byte. Oberon is bad and ugly".
Especially this possibly is need for two-byte comparsions and some
other arithmetic operations.

Maximum what I understand for unsigned types are only one thing:
unsigned types must be moved to pseudo-module SYSTEM.
Maybe for begin add unsigned types as aliases of signed types?

Is unsigned really need in Ofront for developing for 6502 CPU?
What do you say?

-- 
Oleg N. Cher
http://zx.oberon2.ru/
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Received on Wed Apr 25 2012 - 20:29:14 UTC