collapseos/blk/397

( Now we have "as late as possible" stuff. See B70 and B260. )
: _bchk DUP 0x7f + 0xff > IF LIT< br-ovfl (print) ABORT THEN ;
: DO 0x33 ( 2>R ) , H@ ; IMMEDIATE
: LOOP 0x43 ( loop ) , H@ - _bchk C, ; IMMEDIATE
( LEAVE is implemented in low xcomp )
: LITN 0x23 ( n ) , , ;
( gets its name at the very end. can't comment afterwards )
: _ BEGIN LIT< ) WORD S= UNTIL ; IMMEDIATE
: _ ( : will get its name almost at the very end )
    (entry) 1 ( compiled ) C,
    BEGIN
        WORD FIND
        IF ( is word ) DUP IMMED? IF EXECUTE ELSE , THEN
        ELSE ( maybe number ) (parse) LITN THEN
    AGAIN ;
Extract (n) code from stable ABI 2020-07-05 14:13:01 -04:00			`( Now we have "as late as possible" stuff. See B70 and B260. )`
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 10:01:46 -04:00			`: _bchk DUP 0x7f + 0xff > IF LIT< br-ovfl (print) ABORT THEN ;`
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			`: DO 0x33 ( 2>R ) , H@ ; IMMEDIATE`
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			`: LOOP 0x43 ( loop ) , H@ - _bchk C, ; IMMEDIATE`
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			`( LEAVE is implemented in low xcomp )`
Extract (n) code from stable ABI 2020-07-05 14:13:01 -04:00			`: LITN 0x23 ( n ) , , ;`
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			`( gets its name at the very end. can't comment afterwards )`
			`: _ BEGIN LIT< ) WORD S= UNTIL ; IMMEDIATE`
			`: _ ( : will get its name almost at the very end )`
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			`(entry) 1 ( compiled ) C,`
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			`BEGIN`
			`WORD FIND`
			`IF ( is word ) DUP IMMED? IF EXECUTE ELSE , THEN`
			`ELSE ( maybe number ) (parse) LITN THEN`
			`AGAIN ;`