--- gforth/look.fs	1997/08/31 19:31:29	1.9
+++ gforth/look.fs	2003/01/04 08:26:57	1.22
@@ -1,6 +1,6 @@
 \ LOOK.FS      xt -> lfa                               22may93jaw
 
-\ Copyright (C) 1995 Free Software Foundation, Inc.
+\ Copyright (C) 1995,1996,1997,2000 Free Software Foundation, Inc.
 
 \ This file is part of Gforth.
 
@@ -16,7 +16,7 @@
 
 \ You should have received a copy of the GNU General Public License
 \ along with this program; if not, write to the Free Software
-\ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+\ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 
 \ Look checks first if the word is a primitive. If yes then the
 \ vocabulary in the primitive area is beeing searched, meaning
@@ -26,52 +26,99 @@
 \ 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
 
 \ look                                                  17may93jaw
 
 \ rename to discover!!!
 
-: (look)  ( xt startlfa -- lfa flag )
-        false swap
-        BEGIN @ dup
-        WHILE dup name>int
-              3 pick = IF nip dup THEN
-        REPEAT
-        drop nip
-        dup 0<> ;
+: xt>threaded ( xt -- x )
+\G produces the threaded-code cell for the primitive xt
+    threading-method 0= if
+	@
+    then ;
 
+: (look)  ( xt startlfa -- lfa flag )
+    \ 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
+    dup 0<> ;
+
+: 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 
+has? rom 
 [IF]
+: prim>name ( xt -- nt flag )
+    forth-wordlist @ (look) ;
+
 : look
     dup [ unlock rom-dictionary area lock ] 
     literal literal within
     IF
-	>name dup ?? <>
+	>head-noprim dup ?? <>
     ELSE
-	forth-wordlist @ (look)
+	xt>threaded threaded>name
     THEN ;
 [ELSE]
 : look ( cfa -- lfa flag )
-    >name dup ??? <> ;
+    >head-noprim dup ??? <> ;
 [THEN]
 
 [ELSE]
 
-: PrimStart ['] true >name ;
+: PrimStart ['] true >head-noprim ;
+
+: prim>name ( xt -- lfa flag )
+    PrimStart (look) ;
 
 : look ( cfa -- lfa flag )
-    dup dictionary-end forthstart within
+    dup in-dictionary?
     IF
-	PrimStart (look)
+	>head-noprim dup ??? <>
     ELSE
-	>name dup ??? <>
+	prim>name
     THEN ;
 
 [THEN]
 [THEN]
+
+: threaded>name ( ca -- lfa flag )
+    threaded>xt prim>name ;
+
+: >head ( cfa -- nt|0 ) \ gforth to-head
+    \G tries to find the name token nt of the word represented by cfa;
+    \G returns 0 if it fails.  This word is not absolutely reliable,
+    \G it may give false positives and produce wrong nts.
+    look and ;
+
+' >head ALIAS >name \ gforth to-name
+\G old name of @code{>head}