764b2222c7
This will allow us to support backward branching with just one new (bbr) word.
Also, this allow us to have "(" word sooned in core.fth and thus allow for
earlier commenting.
31 lines
1.0 KiB
Forth
31 lines
1.0 KiB
Forth
: H HERE @ ;
|
|
: -^ SWAP - ;
|
|
: +! SWAP OVER @ + SWAP ! ;
|
|
: ALLOT HERE +! ;
|
|
: , H ! 2 ALLOT ;
|
|
: C, H C! 1 ALLOT ;
|
|
: NOT 1 SWAP SKIP? EXIT 0 * ;
|
|
: RECURSE R> R> 2 - >R >R EXIT ;
|
|
: ( LIT@ ) WORD SCMP NOT SKIP? RECURSE ; IMMEDIATE
|
|
( 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 )
|
|
( NOT: a bit convulted because we don't have IF yet )
|
|
( RECURSE: RS TOS is for RECURSE itself, then we have to dig )
|
|
( one more level to get to RECURSE's parent's caller. )
|
|
( IF true, skip following (fbr). Also, push br cell ref H, )
|
|
( to PS )
|
|
: IF ['] SKIP? , ['] (fbr) , H 1 ALLOT ; IMMEDIATE
|
|
( Subtract TOS from H to get offset to write to IF or ELSE's )
|
|
( br cell )
|
|
: THEN DUP H -^ SWAP C! ; IMMEDIATE
|
|
( write (fbr) addr, allot, then same as THEN )
|
|
: ELSE ['] (fbr) , 1 ALLOT DUP H -^ SWAP C! H 1 - ; IMMEDIATE
|
|
: ? @ . ;
|
|
: VARIABLE CREATE 2 ALLOT ;
|
|
: CONSTANT CREATE H ! DOES> @ ;
|
|
: = CMP NOT ;
|
|
: < CMP 0 1 - = ;
|
|
: > CMP 1 = ;
|