rajamesandClaude Opus 5.5
25fc5fd5e3
ENGINE.md 3b, the node's side of ruling A (a word's code is the node's, its
accounts the kernel's).
- dict.v4, system.v4: (WORD-DEFINED) ( xt -- ) is run when an entry is
made, (WORD-FORGOTTEN) ( w -- ) when FORGET or COLD removes entries; with
0 there no one is told, as on the hosted product
- test_host_quit.c: a kernel that keeps the list of words and is checked to
hold exactly the node's dictionary after definitions, a vocabulary, an
abandoned definition, FORGET, a refused FORGET and COLD; KERNEL-WORD
called from the prompt and from a definition
Fixed, found while writing that test: since the capsules moved from build
time to boot time (294e6946), what COLD returns to and FORGET protects was
still the nucleus alone, so COLD lost U*, U/MOD and BYE and FORGET U* was
allowed. The boot now seals the system when it has loaded it
(v4_image_seal), and hosted-check checks COLD, the capsule word after it,
the refused FORGET and BYE.
Verified: make -C v4 test passes at both widths (1283 checks in
test_host_quit.c); hosted-check passes on three ISAs; clean qemu with
STARFORTH_V4=1 on amd64, aarch64 and riscv64 passes POST, and COLD, U*
after it, FORGET U* (refused), an unserved kernel word and BYE typed at
each prompt are answered correctly (logs/20261005-193045, -193307, -193636).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
234 lines
9.5 KiB
Plaintext
234 lines
9.5 KiB
Plaintext
\ dict.v4 -- the dictionary: its space, its entries, and looking a name up.
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\
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\ DECOMPOSITION.md 5.12 and 5.13: HERE ALIGN ALLOT , C, 2, PAD LATEST, FIND ' ,
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\ and the entry-field words >LINK LFA LINK> >NAME NFA NAME> CFA PFA >BODY
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\ TRAVERSE SMUDGE HIDDEN. Part of the compiler capsule: it runs on the host
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\ node. Rests on core.v4 and input.v4.
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\
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\ AN ENTRY. A word's execution address (xt) is the address of its code, and
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\ everything else is found from it:
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\
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\ name the count byte, then the characters, four bytes to a cell,
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\ padded with zeros to a whole cell
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\ xt - 3 flags: 1 immediate, 2 hidden, 4 data
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\ xt - 2 the word address of the name
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\ xt - 1 the link: the xt of the entry before this one, 0 for the first
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\ xt the code
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\
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\ A name holds at most 31 characters; longer ones are cut to 31 both when
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\ defined and when looked up, so 31 characters are significant (FORTH-79).
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\ A "data" word is one whose code is a single call to its run-time routine,
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\ with its parameter field in the cell after it: xt + 1. For any other word
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\ the parameter field is the code itself.
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\
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\ THE SPACE. DP is a byte address, so that C, can pack characters; HERE is
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\ the next whole cell. An address unit is a cell (D-1): ALLOT counts cells.
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\
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\ Constants the loader supplies:
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\ DP word address of the variable: the next free byte
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\ (LATEST) word address of the variable: the xt of the newest entry of the
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\ FORTH vocabulary, or 0
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\ CONTEXT CURRENT word addresses of the variables: each holds the address
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\ of a vocabulary's head cell -- the cell that holds the xt of
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\ that vocabulary's newest entry. FORTH's head cell is (LATEST).
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\
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\ VOCABULARIES (FORTH-79). A name is looked up in the CONTEXT vocabulary and
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\ then, if that is not FORTH, in FORTH. A new entry goes into the CURRENT
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\ vocabulary: it is linked to that vocabulary's newest entry and becomes it.
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\ DBASE DLIMIT byte addresses of the start and end of dictionary space
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\ PAD byte address of the scratch area for strings, 84 bytes or more
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\ (D) word address of five cells of scratch for this file
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\ (WORD-DEFINED) (WORD-FORGOTTEN) word addresses of two variables: see
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\ "telling the kernel" below
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\ PAD is in line.
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macro 4* 2* 2* endmacro
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macro 4/ 2/ 2/ endmacro
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macro OR over inv and xor endmacro
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\ ---- the space (5.12) ------------------------------------------------------
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\ These reach DP through B and leave A alone, so that , and C, can keep what
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\ they are storing in A while the space is taken: nothing of theirs is then
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\ on the data stack under (DP+), which itself needs three cells (D-2).
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: (DERR) ( -- 0 ) NODE-ERROR b! 5 !b 0 ; \ dictionary full
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\ ( n -- flag ) move DP by n bytes if it stays inside the dictionary space
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\ and say -1; otherwise leave it, set NODE-ERROR and say 0. The two
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\ subtractions are x + ~y + 1, which unlike the in-line - needs no return
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\ entry: these words are called at the bottom of long chains of calls.
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: (DP+)
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DP b! @b +
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dup DBASE inv + 1 + -if LOW drop drop jump (DERR) \ new - DBASE
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LOW: drop dup inv DLIMIT + 1 + -if HIGH drop drop jump (DERR) \ DLIMIT - new
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HIGH: drop DP b! !b -1 ;
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header HERE
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: HERE ( -- addr ) DP b! @b 3 + 4/ ;
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header ALIGN
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: ALIGN ( -- ) DP b! @b 3 + -4 and !b ;
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header ALLOT
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: ALLOT ( n -- ) ALIGN 4* (DP+) drop ;
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\ , calls nothing: the code generator calls it from as deep as anything goes.
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header ,
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: , ( x -- )
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a!
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DP b! @b 3 + -4 and \ the next whole cell, as a byte address
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dup inv DLIMIT + -3 + -if ROOM \ DLIMIT - (it + 4)
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drop drop NODE-ERROR b! 5 !b ;
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ROOM: drop dup 4 + !b \ DP is past it
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4/ b! a !b ;
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header C,
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: C, ( c -- )
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a! 1 (DP+) if FULL
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drop a DP b! @b -1 + jump C!
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FULL: drop ;
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header 2,
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: 2, ( lo hi -- ) SWAP , , ; \ the low cell first, as v3
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header LATEST
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: LATEST ( -- xt ) CURRENT a! @ a! @ ; \ the newest entry of the CURRENT vocabulary
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\ ---- the fields of an entry (5.13) -----------------------------------------
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: (FLAGS) ( xt -- addr ) -3 + ;
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header >LINK
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: >LINK ( xt -- addr ) -1 + ;
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header LFA
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: LFA ( xt -- addr ) jump >LINK
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header LINK>
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: LINK> ( addr -- xt ) a! @ ;
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header >NAME
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: >NAME ( xt -- baddr ) -2 + a! @ 4* ;
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header NFA
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: NFA ( xt -- baddr ) jump >NAME
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header NAME>
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: NAME> ( baddr -- xt ) dup C@ 31 and 4 + 4/ push 4/ pop + 3 + ;
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header CFA
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: CFA ( xt -- xt ) ;
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header PFA
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: PFA ( xt -- addr ) dup (FLAGS) a! @ 4 and if CODE drop 1 + ; CODE: drop ;
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header >BODY
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: >BODY ( xt -- addr ) jump PFA
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\ ( baddr n -- baddr' ) as v3: for n > 0, from a name's count byte to the
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\ byte after its last character; otherwise the address unchanged.
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header TRAVERSE
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: TRAVERSE
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-if NN drop ;
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NN: if ZERO drop dup C@ 31 and + 1 + ;
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ZERO: drop ;
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header SMUDGE
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: SMUDGE ( -- ) LATEST if NONE (FLAGS) a! @ 2 xor ! ; NONE: drop ;
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header HIDDEN
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: HIDDEN ( -- ) LATEST if NONE (FLAGS) a! @ 2 OR ! ; NONE: drop ;
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\ ---- telling the kernel (docs/v4.0.0/ENGINE.md 3b) ------------------------------
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\ A word's code is here on the node; its accounts are a record its kernel
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\ keeps. So the kernel has to be told of every entry that is made and of
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\ every entry that goes. An entry is made in one place, (HEADER); entries go
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\ in two, FORGET and COLD (system.v4). Each tells through a variable that
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\ holds the xt of a word to run, or 0 for a node whose host keeps no records:
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\ (WORD-DEFINED) ( xt -- ) an entry has been made; its code will be at xt
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\ (WORD-FORGOTTEN) ( w -- ) every entry at word address w or above is gone
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\ On the bare-metal system the kernel puts words of its own there.
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\ ( -- ) tell of the entry just made, whose code starts at HERE
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: (DEFINED)
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(WORD-DEFINED) b! @b if NONE HERE SWAP push ;
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NONE: drop ;
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\ ( w -- ) tell that the entries from word address w up have gone
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: (FORGOTTEN)
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(WORD-FORGOTTEN) b! @b if NONE push ;
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NONE: drop drop ;
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\ ---- making an entry -------------------------------------------------------
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\ (D)+0 where the name starts (D)+1 the name being looked up
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\ (D)+2 the name being copied, or the entry being looked at
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\ (D)+3 a count (D)+4 whether a lookup has gone on to FORTH
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\ ( -- bytes ) what an entry for a name of (D)+3 characters takes: its name
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\ cells and three more
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: (NEED) (D)+3 a! @ 4 + -4 and 12 + ;
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\ ( baddr -- ) an entry for the counted string at baddr; its code starts at
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\ HERE afterwards. An empty name, or no room, makes nothing and sets
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\ NODE-ERROR.
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: (HEADER)
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dup (D)+2 a! ! \ (CLIP), in line
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C@ -32 + -if LONG drop jump CLIPPED
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LONG: drop 31 (D)+2 a! @ C!
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CLIPPED:
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(D)+2 a! @ C@ if EMPTY \ len
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(D)+3 a! !
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ALIGN
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(NEED) (DP+) if FULL drop \ there is room;
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(NEED) NEGATE (DP+) drop \ DP back where it was
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HERE (D) a! ! \ where the name starts
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(D)+3 a! @ C,
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L: (D)+3 a! @ if DONE -1 + !
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(D)+2 a! @ 1 + dup ! C@ C,
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jump L
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DONE: drop
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P: DP b! @b 3 and if ALIGNED drop 0 C, jump P
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ALIGNED: drop
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0 , (D) a! @ , LATEST ,
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HERE CURRENT a! @ a! !
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jump (DEFINED)
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FULL: drop ; \ (DP+) has set NODE-ERROR
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EMPTY: drop NODE-ERROR b! 6 !b ; \ name missing
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\ ---- looking a name up -----------------------------------------------------
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\ ( baddr -- xt | 0 ) the newest visible entry named by the counted string.
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\ Written out in one piece -- the string cut to 31, each entry's flags and
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\ name fetched, the two names compared byte by byte -- so that the only call
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\ it makes is C@: it is called from the interpreter for every word of every
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\ line, with the user's return stack beneath it.
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: (LOOKUP)
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dup (D)+1 a! ! \ cut the string to 31 characters
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C@ -32 + -if LONG drop jump CUT
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LONG: drop 31 (D)+1 a! @ C!
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CUT:
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0 (D)+4 a! ! \ not yet on to FORTH
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CONTEXT a! @ a! @
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L: if END
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(D)+2 a! !
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(D)+2 a! @ -3 + a! @ 2 and if VISIBLE drop jump OLDER
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VISIBLE: drop
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(D)+2 a! @ -2 + a! @ 4* (D) a! ! \ its name
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(D)+1 a! @ C@ 1 + (D)+3 a! ! \ the count byte and the characters
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C: (D)+3 a! @ if SAME -1 + dup ! \ k
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dup (D) a! @ + C@ \ k c1
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SWAP (D)+1 a! @ + C@ \ c1 c2
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xor if EQ drop jump OLDER
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EQ: drop jump C
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SAME: drop (D)+2 a! @ ;
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OLDER: (D)+2 a! @ -1 + a! @ jump L
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END: (D)+4 a! @ if FIRST drop ; \ FORTH has been searched: not found
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FIRST: drop -1 (D)+4 a! !
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CONTEXT a! @ (LATEST) xor if ISFORTH \ CONTEXT is FORTH: that was it
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drop drop (LATEST) a! @ jump L
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ISFORTH: drop ;
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\ ( -- xt | 0 ) FORTH-79: the compilation address of the next word in the
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\ input stream, or 0 if it is not in the dictionary.
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header FIND
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: FIND 32 WORD jump (LOOKUP)
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\ ( -- addr ) FORTH-79: the parameter field address of the next word in the
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\ input stream. Not found is an error: 0, and NODE-ERROR is set. This is '
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\ when interpreting; compile.v4 adds what ' does when compiling.
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\ ( -- 0 ) say that the word WORD has just left is not known, as v3 does:
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\ UNKNOWN WORD: 'xxx'
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: (UNKNOWN)
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$4E4B4E55 (EMIT4) $204E574F (EMIT4) $44524F57 (EMIT4) $27203A (EMIT4)
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WBUF COUNT TYPE 39 EMIT CR
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NODE-ERROR b! -1 !b 0 ;
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: (') 32 WORD (LOOKUP) if MISSING jump PFA
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MISSING: drop jump (UNKNOWN)
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