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Commit Graph

10 Commits

Author SHA1 Message Date
Virgil Dupras
a7dcb522c2 Make br cells 1 byte wide
The 1 byte limitation has been effective for a while now, but I
hadn't made the move yet, I wanted to see if the limitation would
cause me problems. It doesn't.

Doing this now slightly facilitates the IY->BC move in z80.

Bootstrapping: if you try to recreate the CVM binary from the
previous commit with this code, you'll have bootstrapping problems.
The first bootstrap will compile a binary with 2-bytes wide cells
but branching conditionals that yields 1-byte cells. That's bad.

I got around the issue by temporarily inserting a "397 399 LOADR"
instruction in cvm/xcomp.fs, right before the xcomp overrides. This
way, I force 1-byte cells everywhere on the first compiliation,
which then allows me to apply the logic change in cvm/vm.c and have
a properly running binary.
2020-07-06 07:27:50 -04:00
Virgil Dupras
f2f520cacc Extract (br), (?br) and (loop)'s code out of stable ABI zone
There is now no more actual code in stable ABI, only references.
This makes refactoring of this code much easier. For example,
changing IY to BC as the IP register.
2020-07-05 14:57:18 -04:00
Virgil Dupras
daeb3b3c69 Extract (n) code from stable ABI 2020-07-05 14:16:24 -04:00
Virgil Dupras
650481f849 z80/8086: extract 2>R code from stable ABI zone
Only its jump at 0x33 remains.

I've also fixed a strange offset oddity in 8086's (n) placement.
It was off by 2, but strangely, it ran properly. Anyway, now it's
fixed.
2020-07-05 08:03:15 -04:00
Virgil Dupras
94cb76520a Refer to stable wordref by direct offset in "hot zone" immediates
Previously, it was impossible to cross-compile Collapse OS from a
binary-offsetted Collapse OS because stable ABI wordrefs would have
a wrongly offsetted address.

This solves the problem by replacing those wordrefs by direct,
hardcoded stable ABI offset references.
2020-07-05 07:09:11 -04:00
Virgil Dupras
3d2dc041fb Make word routines into word types
Instead of having wordref point to core word routines, I made them
into word 4 word types. It liberates space into the stable ABI and
should make porting to other arches easier.

I'm also thinking of combining word type with the namelen field
for precious bytes saving, but not now...
2020-06-17 21:41:01 -04:00
Virgil Dupras
2be2f74a43 Make literal word routines into regular native words 2020-06-17 14:25:32 -04:00
Virgil Dupras
ed2b91411a Limit ourselves to 8-bit branching
I'm planning on going back to 8-bit branching. 16-bit br cells incur
a non-negligible penalty and, while at first 64 words (128 bytes
forward or backward) seemed a bit limiting, I now don't see why one
would ever construct such a big branch. It would be un-forthy.

Also, I looked at using BC instead of IY to hold IP and the transition
would be a lot easier with 8-bit branching.

In this commit, all I do is add overflow checks in IF. The mechanic
below doesn't change. I'll give myself some time to think it over so
that I avoid yet another back and forth.
2020-05-24 10:16:25 -04:00
Virgil Dupras
bd38d80f9c Move Cross-compiled core from B390 to B350
and renamed it "Core words". Also, reworded the presentation.
2020-05-15 22:44:49 -04:00
Virgil Dupras
44403c3d4c Move icore to blkfs
The way is clear for complete stage1 bootstrapping on the RC2014
target!
2020-04-23 15:14:14 -04:00