Commit Graph

14 Commits

Author SHA1 Message Date
Virgil Dupras
45eceaaf61 Remove indirect memory access
I got bitten again, I've over-designed my solution. The last time
it happened, it was that memory mapping thing I was wanting to add.

The indirect memory access feature I was adding was to solve a
specific problem: Allow Collapse OS to cross-compile directly on a
AT28 EEPROM.

It began well. As long as we were staying in the assembler realm,
things were looking good. However, when we got into the xcomp realm
(B260), things became ugly, and I had to creep up indirection where
I didn't want to.

All of this because I wanted to solve my initial problem in a
slightly more generalized way. The broad idea was that these indirect
memory access could allow xcomp into a broad kind of memory-like
devices.

This idea broke on the "@" part of the equation. If I want
indirections to be two-way and allow xcomp to work properly, I have
to add this indirection to FIND (and possibly others) and this just
isn't practical or elegant.

So, I'm taking a step back and accepting that the solution I design
for now is exclusively for the AT28. What I'm thinking is to add a
low-level hook for memory writing, at the assembly level.
2020-12-07 22:34:53 -05:00
Virgil Dupras
e5a983ab7f Rename A!, A@ and A, to C!*, C@* and C,*
Also, rename "Addressed devices" to "Indirect memory access".

I do this because I need to add indirect versions of !, @ and ,
to allow boostrapping directly to EEPROM and that A,, thing I've
added to assemblers felt like really bad names.

With this change, I'd like to generalize the use of the * suffix
for aliases.
2020-12-07 19:06:58 -05:00
Virgil Dupras
e8cc3040d1 Improve impl's word execution documentation
Add an example, which I think helps a lot to grasp the idea.

Also, improve comments in Z80 boot code.
2020-11-28 13:15:16 -05:00
Virgil Dupras
b48455e4db Improve initialization sequence documentation 2020-11-28 11:17:50 -05:00
Virgil Dupras
f8b7a3ce65 Rename switch to ialias
The switch name was confusing.
2020-11-28 10:58:16 -05:00
Virgil Dupras
7722db0762 Fix mis-documentation in 8086 boot code comments 2020-11-14 20:28:44 -05:00
Virgil Dupras
de7cb4a80f Add word A,
This would be useful, for example, to allow the assembler to write
straight to an AT28 EEPROM without going to RAM. This would be a
life saver in machines with tight RAM such as the SMS.
2020-10-28 20:45:50 -04:00
Virgil Dupras
adea75e50a Add alias and switch word types
I'm pretty happy about how lightweight the implementation turns
out to be.
2020-10-28 15:02:06 -04:00
Virgil Dupras
b1a95648f1 De-stabilize EXIT
This marks the end of wordrefs in stable ABI. Nice.
2020-09-19 20:35:35 -04:00
Virgil Dupras
53239c8f84 De-stabilize (n) 2020-09-19 19:44:15 -04:00
Virgil Dupras
eefbf66e95 De-stabilize (br), (?br), (loop), (s)
When writing the xcomp documentation, I realized that with careful
threading and by accepting a bit of code duplication in the xcomp
toolset, I could de-stabilize a couple of words.

(n) and EXIT are a bit trickier, but I think it can be done. It
would be nice to get rid of stable wordrefs...
2020-09-19 13:54:01 -04:00
Virgil Dupras
6d180f737a doc: fix typos and inaccuracies 2020-09-19 09:04:18 -04:00
Virgil Dupras
82b0b81521 doc: fix a few typos and inaccuracies 2020-09-18 21:13:28 -04:00
Virgil Dupras
d03d93668f doc: take implementation notes out of blkfs 2020-08-16 08:08:23 -04:00