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48078d9c9c
There is an alternate git history where I continued the Forth-ification of words, including "SKIP?", but that was a bad idea: because that word was written by flow control immediates, I stepped into quicksands where stability became necessary in z80c.fs and I couldn't gracefully get out of it. I'm stepping back and take this opportunity to replace the shoddy SKIP? algo with a more straightforward (?br) implementation. (br) and (?br) will always stay in boot code where it's easier manage a stable ABI.
106 lines
2.7 KiB
Forth
106 lines
2.7 KiB
Forth
: H@ HERE @ ;
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: -^ SWAP - ;
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: [ INTERPRET 1 FLAGS ! ; IMMEDIATE
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: ] R> DROP ;
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: LIT JTBL 26 + , ;
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: LITS LIT SCPY ;
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: LIT< WORD LITS ; IMMEDIATE
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: _err LIT< word-not-found (print) ABORT ;
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: ' WORD (find) NOT (?br) [ 4 , ] _err ;
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: ['] ' LITN ; IMMEDIATE
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: COMPILE ' LITN ['] , , ; IMMEDIATE
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: [COMPILE] ' , ; IMMEDIATE
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: BEGIN H@ ; IMMEDIATE
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: AGAIN COMPILE (br) H@ - , ; IMMEDIATE
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: UNTIL COMPILE (?br) H@ - , ; IMMEDIATE
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: ( BEGIN LIT< ) WORD SCMP NOT UNTIL ; IMMEDIATE
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( Hello, hello, krkrkrkr... do you hear me?
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Ah, voice at last! Some lines above need comments
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BTW: Forth lines limited to 64 cols because of default
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input buffer size in Collapse OS
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"_": words starting with "_" are meant to be "private",
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that is, only used by their immediate surrondings.
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COMPILE: Tough one. Get addr of caller word (example above
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(br)) and then call LITN on it. )
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: +! SWAP OVER @ + SWAP ! ;
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: ALLOT HERE +! ;
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: IF ( -- a | a: br cell addr )
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COMPILE (?br)
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H@ ( push a )
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2 ALLOT ( br cell allot )
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; IMMEDIATE
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: THEN ( a -- | a: br cell addr )
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DUP H@ -^ SWAP ( a-H a )
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!
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; IMMEDIATE
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: ELSE ( a1 -- a2 | a1: IF cell a2: ELSE cell )
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COMPILE (br)
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2 ALLOT
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DUP H@ -^ SWAP ( a-H a )
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!
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H@ 2 - ( push a. -2 for allot offset )
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; IMMEDIATE
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: CREATE
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(entry) ( empty header with name )
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[ JTBL 3 + LITN ] ( push cellWord addr )
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, ( write it )
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;
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: VARIABLE CREATE 2 ALLOT ;
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: CONSTANT CREATE H@ ! DOES> @ ;
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: = CMP NOT ;
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: < CMP 0 1 - = ;
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: > CMP 1 = ;
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: / /MOD SWAP DROP ;
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: MOD /MOD DROP ;
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( In addition to pushing H@ this compiles 2 >R so that loop
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variables are sent to PS at runtime )
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: DO
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COMPILE SWAP COMPILE >R COMPILE >R
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H@
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; IMMEDIATE
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( One could think that we should have a sub word to avoid all
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these COMPILE, but we can't because otherwise it messes with
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the RS )
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: LOOP
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COMPILE R> 1 LITN COMPILE + COMPILE DUP COMPILE >R
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COMPILE I' COMPILE = COMPILE (?br)
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H@ - ,
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COMPILE R> COMPILE DROP COMPILE R> COMPILE DROP
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; IMMEDIATE
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( WARNING: there are no limit checks. We must be cautious, in
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core code, not to create more than SYSV_BUFSIZE/2 sys vars.
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Also: SYSV shouldn't be used during runtime: SYSVNXT won't
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point at the right place. It should only be used during
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stage1 compilation. This is why this word is not documented
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in dictionary.txt )
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: (sysv)
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(entry)
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[ JTBL LITN ] ,
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SYSVNXT @ ,
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2 SYSVNXT +!
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;
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: ."
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LIT
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BEGIN
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C< DUP ( c c )
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( 34 is ASCII for " )
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DUP 34 = IF DROP DROP 0 0 THEN
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C,
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0 = UNTIL
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COMPILE (print)
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; IMMEDIATE
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: ABORT" [COMPILE] ." COMPILE ABORT ; IMMEDIATE
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