--- gforth/look.fs	1994/02/11 16:30:46	1.1
+++ gforth/look.fs	2007/12/31 18:40:24	1.28
@@ -1,5 +1,22 @@
 \ LOOK.FS      xt -> lfa                               22may93jaw
 
+\ Copyright (C) 1995,1996,1997,2000,2003 Free Software Foundation, Inc.
+
+\ This file is part of Gforth.
+
+\ Gforth is free software; you can redistribute it and/or
+\ modify it under the terms of the GNU General Public License
+\ as published by the Free Software Foundation, either version 3
+\ of the License, or (at your option) any later version.
+
+\ This program is distributed in the hope that it will be useful,
+\ but WITHOUT ANY WARRANTY; without even the implied warranty of
+\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+\ GNU General Public License for more details.
+
+\ You should have received a copy of the GNU General Public License
+\ along with this program. If not, see http://www.gnu.org/licenses/.
+
 \ Look checks first if the word is a primitive. If yes then the
 \ vocabulary in the primitive area is beeing searched, meaning
 \ creating for each word a xt and comparing it...
@@ -8,30 +25,99 @@
 \ Problems: A compiled xt via compile, might be created with noname:
 \           a noname: leaves now a empty name field
 
+require stuff.fs
+require environ.fs
+
 decimal
 
-\ >NAME PRIMSTART                                       22may93jaw
+\ look                                                  17may93jaw
 
-\ : >name ( xt -- nfa )
-\         BEGIN   1 chars -
-\                 dup c@ 128 and
-\         UNTIL ;
+\ rename to discover!!!
 
-: PrimStart ['] true >name ;
+: xt>threaded ( xt -- x )
+\G produces the threaded-code cell for the primitive xt
+    threading-method 0= if
+	@
+    then ;
+
+: search-name  ( xt startlfa -- nt|0 )
+    \ look up name of primitive with code at xt
+    swap
+    >r false swap
+    BEGIN
+	@ dup
+    WHILE
+	    dup name>int
+	    r@ = IF
+		nip dup
+	    THEN
+    REPEAT
+    drop rdrop ;
+
+: threaded>xt ( ca -- xt|0 )
+\G For the code address ca of a primitive, find the xt (or 0).
+    [IFDEF] decompile-prim
+	decompile-prim
+    [THEN]
+     \ walk through the array of primitive CAs
+    >r ['] noop begin
+	dup @ while
+	    dup xt>threaded r@ = if
+		rdrop exit
+	    endif
+	    cell+
+    repeat
+    drop rdrop 0 ;
+
+\ !!! nicht optimal!
+[IFUNDEF] look
+has? ec [IF]
+
+has? rom 
+[IF]
+: prim>name ( xt -- nt|0 )
+    forth-wordlist @ search-name ;
+
+: look ( xt -- lfa flag )
+    dup [ unlock rom-dictionary area lock ] 
+    literal literal within
+    IF
+	>head-noprim dup ?? <>
+    ELSE
+	prim>name dup 0<>
+    THEN ;
+[ELSE]
+: look ( cfa -- lfa flag )
+    >head-noprim dup ??? <> ;
+[THEN]
 
-\ look                                                  17may93jaw
+[ELSE]
 
-: (look)  ( xt startlfa -- lfa flag )
-        false swap
-        BEGIN @ dup
-        WHILE dup cell+ name>
-              3 pick = IF nip dup THEN
-        REPEAT
-        drop nip
-        dup 0<> ;
+: PrimStart ['] true >head-noprim ;
 
-: look ( cfa -- lfa flag )
-        dup forthstart u<
-        IF PrimStart (look)
-        ELSE >name true THEN ;
+: prim>name ( xt -- nt|0 )
+    PrimStart search-name ;
+
+: look ( xt -- lfa flag )
+    dup in-dictionary?
+    IF
+	>head-noprim dup ??? <>
+    ELSE
+	prim>name dup 0<>
+    THEN ;
+
+[THEN]
+[THEN]
+
+: threaded>name ( ca -- nt|0 )
+    threaded>xt prim>name ;
+
+: >name ( xt -- nt|0 ) \ gforth to-name
+    \G tries to find the name token @var{nt} of the word represented
+    \G by @var{xt}; returns 0 if it fails.  This word is not
+    \G absolutely reliable, it may give false positives and produce
+    \G wrong nts.
+    look and ;
 
+' >name ALIAS >head \ gforth to-head
+\G another name of @code{>name}