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forth: Add "DO" and "LOOP"

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Also, un-IMMEDIATE "LITN" it didn't make any sense.
This commit is contained in:
Virgil Dupras 2020-03-18 20:04:44 -04:00
parent 587d1d0d69
commit d874f20278
3 changed files with 21 additions and 6 deletions
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23
apps/forth/core.fs
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@ -3,7 +3,7 @@
: +! SWAP OVER @ + SWAP ! ; : +! SWAP OVER @ + SWAP ! ;
: ALLOT HERE +! ; : ALLOT HERE +! ;
: C, H C! 1 ALLOT ; : C, H C! 1 ALLOT ;
: COMPILE ' ['] LITN EXECUTE ['] , , ; IMMEDIATE : COMPILE ' LITN ['] , , ; IMMEDIATE
: BEGIN H ; IMMEDIATE : BEGIN H ; IMMEDIATE
: AGAIN COMPILE (bbr) H -^ C, ; IMMEDIATE : AGAIN COMPILE (bbr) H -^ C, ; IMMEDIATE
: UNTIL COMPILE SKIP? COMPILE (bbr) H -^ C, ; IMMEDIATE : UNTIL COMPILE SKIP? COMPILE (bbr) H -^ C, ; IMMEDIATE
@ -15,9 +15,7 @@
input buffer size in Collapse OS input buffer size in Collapse OS
COMPILE; Tough one. Get addr of caller word (example above COMPILE; Tough one. Get addr of caller word (example above
(bbr)) and then call LITN on it. However, LITN is an (bbr)) and then call LITN on it.
immediate and has to be indirectly executed. Then, write
a reference to "," so that this word is written to HERE.
NOT: a bit convulted because we don't have IF yet ) NOT: a bit convulted because we don't have IF yet )
@ -49,3 +47,20 @@
: > CMP 1 = ; : > CMP 1 = ;
: / /MOD SWAP DROP ; : / /MOD SWAP DROP ;
: MOD /MOD DROP ; : MOD /MOD DROP ;
( In addition to pushing H this compiles 2 >R so that loop variables are sent
to PS at runtime )
: DO
COMPILE SWAP COMPILE >R COMPILE >R
H
; IMMEDIATE
( 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 R> 1 LITN COMPILE + COMPILE DUP COMPILE >R
COMPILE I' COMPILE = COMPILE SKIP? COMPILE (bbr)
H -^ C,
COMPILE R> COMPILE DROP COMPILE R> COMPILE DROP
; IMMEDIATE

2
apps/forth/dict.asm
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@ -444,7 +444,7 @@ ISIMMED:
.db "LITN" .db "LITN"
.fill 3 .fill 3
.dw ISIMMED .dw ISIMMED
.db 1 ; IMMEDIATE .db 0
LITN: LITN:
.dw nativeWord .dw nativeWord
ld hl, (HERE) ld hl, (HERE)

2
apps/forth/dictionary.txt
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@ -50,7 +50,7 @@ CONSTANT x n -- Creates cell x that when called pushes its value
DOES> -- See description at top of file DOES> -- See description at top of file
IMMED? a -- f Checks whether wordref at a is immediate. IMMED? a -- f Checks whether wordref at a is immediate.
IMMEDIATE -- Flag the latest defined word as immediate. IMMEDIATE -- Flag the latest defined word as immediate.
LITN n -- *I* Inserts number from TOS as a literal LITN n -- Write number n as a literal.
VARIABLE c -- Creates cell x with 2 bytes allocation. VARIABLE c -- Creates cell x with 2 bytes allocation.
Compilation vs meta-compilation. When you compile a word with "[COMPILE] foo", Compilation vs meta-compilation. When you compile a word with "[COMPILE] foo",