collapseos/forth/core.fs

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: H@ HERE @ ;
: IMMEDIATE
CURRENT @ 1-
DUP C@ 128 OR SWAP C!
;
: [ INTERPRET ; IMMEDIATE
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: ] R> DROP ;
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: LITS 34 , SCPY ;
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: LIT< WORD LITS ; IMMEDIATE
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: LITA 36 , , ;
: '
WORD (find) (?br) [ 4 , ] EXIT
LIT< (wnf) (find) DROP EXECUTE
;
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: ['] ' LITA ; IMMEDIATE
: COMPILE ' LITA ['] , , ; IMMEDIATE
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: [COMPILE] ' , ; IMMEDIATE
: BEGIN H@ ; IMMEDIATE
: AGAIN COMPILE (br) H@ - , ; IMMEDIATE
: UNTIL COMPILE (?br) H@ - , ; IMMEDIATE
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: _ BEGIN LIT< ) WORD S= UNTIL ; IMMEDIATE
40 CURRENT @ 4 - C!
( Hello, hello, krkrkrkr... do you hear me?
Ah, voice at last! Some lines above need comments
BTW: Forth lines limited to 64 cols because of default
input buffer size in Collapse OS
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"_": words starting with "_" are meant to be "private",
that is, only used by their immediate surrondings.
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40 is ASCII for '('. We do this to simplify XPACK's task of
not mistakenly consider '(' definition as a comment.
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LITS: 34 == litWord
LITA: 36 == addrWord
COMPILE: Tough one. Get addr of caller word (example above
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(br)) and then call LITA on it. )
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: +! SWAP OVER @ + SWAP ! ;
: -^ SWAP - ;
: ALLOT HERE +! ;
: IF ( -- a | a: br cell addr )
COMPILE (?br)
H@ ( push a )
2 ALLOT ( br cell allot )
; IMMEDIATE
: THEN ( a -- | a: br cell addr )
DUP H@ -^ SWAP ( a-H a )
!
; IMMEDIATE
: ELSE ( a1 -- a2 | a1: IF cell a2: ELSE cell )
COMPILE (br)
2 ALLOT
DUP H@ -^ SWAP ( a-H a )
!
H@ 2- ( push a. -2 for allot offset )
; IMMEDIATE
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( During a CASE, the stack grows by 1 at each ENDOF so that
we can fill all those ENDOF branching addrs. So that we
know when to stop, we put a 0 on PSP. That's our stopgap. )
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: CASE 0 COMPILE >R ; IMMEDIATE
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: OF
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COMPILE I COMPILE =
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[COMPILE] IF
; IMMEDIATE
: ENDOF [COMPILE] ELSE ; IMMEDIATE
( At this point, we have something like "0 e1 e2 e3 val". We
want top drop val, and then call THEN as long as we don't
hit 0. )
: ENDCASE
BEGIN
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DUP NOT IF
DROP COMPILE R> COMPILE DROP EXIT
THEN
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[COMPILE] THEN
AGAIN
; IMMEDIATE
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: CREATE
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(entry) ( empty header with name )
11 ( 11 == cellWord )
C, ( write it )
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;
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( We run this when we're in an entry creation context. Many
things we need to do.
1. Change the code link to doesWord
2. Leave 2 bytes for regular cell variable.
3. Write down RS' RTOS to entry.
4. exit parent definition
)
: DOES>
( Overwrite cellWord in CURRENT )
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( 43 == doesWord )
43 CURRENT @ C!
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( When we have a DOES>, we forcefully place HERE to 4
bytes after CURRENT. This allows a DOES word to use ","
and "C," without messing everything up. )
CURRENT @ 3 + HERE !
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( HERE points to where we should write R> )
R> ,
( We're done. Because we've popped RS, we'll exit parent
definition )
;
: VARIABLE CREATE 2 ALLOT ;
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: CONSTANT CREATE , DOES> @ ;
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: / /MOD SWAP DROP ;
: MOD /MOD DROP ;
( In addition to pushing H@ this compiles 2 >R so that loop
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variables are sent to PS at runtime )
: DO
COMPILE SWAP COMPILE >R COMPILE >R
H@
; IMMEDIATE
( Increase loop counter and returns whether we should loop. )
: _
R> ( IP, keep for later )
R> 1+ ( ip i+1 )
DUP >R ( ip i )
I' = ( ip f )
SWAP >R ( f )
;
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( One could think that we should have a sub word to avoid all
these COMPILE, but we can't because otherwise it messes with
the RS )
: LOOP
COMPILE _ COMPILE (?br)
H@ - ,
COMPILE R> COMPILE DROP COMPILE R> COMPILE DROP
; IMMEDIATE
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: LEAVE R> R> DROP I 1- >R >R ;
: ROLL
DUP NOT IF EXIT THEN
1+ DUP PICK ( n val )
SWAP 2 * (roll) ( val )
SWAP DROP
;
: 2DUP OVER OVER ;
: 2OVER 3 PICK 3 PICK ;
: 2SWAP 3 ROLL 3 ROLL ;
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( a1 a2 u -- )
: MOVE
( u ) 0 DO
SWAP DUP I + C@ ( a2 a1 x )
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ROT SWAP OVER I + ( a1 a2 x a2 )
C! ( a1 a2 )
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LOOP
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2DROP
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;
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: DELW
1- 0 SWAP C!
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;
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: PREV
3 - DUP @ ( a o )
- ( a-o )
;
: WORD(
DUP 1- C@ ( name len field )
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127 AND ( 0x7f. remove IMMEDIATE flag )
3 + ( fixed header len )
-
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;
: FORGET
' DUP ( w w )
( HERE must be at the end of prev's word, that is, at the
beginning of w. )
WORD( HERE ! ( w )
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PREV CURRENT !
;
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: EMPTY
LIT< _sys (find) NOT IF ABORT THEN
DUP HERE ! CURRENT !
;
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( Drop RSP until I-2 == INTERPRET. )
: EXIT!
['] INTERPRET ( I )
BEGIN ( I )
DUP ( I I )
R> DROP I 2- @ ( I I a )
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= UNTIL
DROP
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;
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( a -- a+1 c )
: C@+ DUP C@ SWAP 1+ SWAP ;