File:  [gforth] / gforth / look.fs
Revision 1.22: download - view: text, annotated - select for diffs
Sat Jan 4 08:26:57 2003 UTC (18 years, 8 months ago) by anton
Branches: MAIN
CVS tags: HEAD
bugfix: LOOK works again for xts of primitives
new words: threaded>xt, prim>name, threaded>name (stack effect not final)

    1: \ LOOK.FS      xt -> lfa                               22may93jaw
    2: 
    3: \ Copyright (C) 1995,1996,1997,2000 Free Software Foundation, Inc.
    4: 
    5: \ This file is part of Gforth.
    6: 
    7: \ Gforth is free software; you can redistribute it and/or
    8: \ modify it under the terms of the GNU General Public License
    9: \ as published by the Free Software Foundation; either version 2
   10: \ of the License, or (at your option) any later version.
   11: 
   12: \ This program is distributed in the hope that it will be useful,
   13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
   14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15: \ GNU General Public License for more details.
   16: 
   17: \ You should have received a copy of the GNU General Public License
   18: \ along with this program; if not, write to the Free Software
   19: \ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
   20: 
   21: \ Look checks first if the word is a primitive. If yes then the
   22: \ vocabulary in the primitive area is beeing searched, meaning
   23: \ creating for each word a xt and comparing it...
   24: 
   25: \ If a word is no primitive look searches backwards to find the nfa.
   26: \ Problems: A compiled xt via compile, might be created with noname:
   27: \           a noname: leaves now a empty name field
   28: 
   29: require stuff.fs
   30: require environ.fs
   31: 
   32: decimal
   33: 
   34: \ look                                                  17may93jaw
   35: 
   36: \ rename to discover!!!
   37: 
   38: : xt>threaded ( xt -- x )
   39: \G produces the threaded-code cell for the primitive xt
   40:     threading-method 0= if
   41: 	@
   42:     then ;
   43: 
   44: : (look)  ( xt startlfa -- lfa flag )
   45:     \ look up name of primitive with code at xt
   46:     swap
   47:     >r false swap
   48:     BEGIN
   49: 	@ dup
   50:     WHILE
   51: 	    dup name>int
   52: 	    r@ = IF
   53: 		nip dup
   54: 	    THEN
   55:     REPEAT
   56:     drop rdrop
   57:     dup 0<> ;
   58: 
   59: : threaded>xt ( ca -- xt|0 )
   60: \G For the code address ca of a primitive, find the xt (or 0).
   61:     [IFDEF] decompile-prim
   62: 	decompile-prim
   63:     [THEN]
   64:      \ walk through the array of primitive CAs
   65:     >r ['] noop begin
   66: 	dup @ while
   67: 	    dup xt>threaded r@ = if
   68: 		rdrop exit
   69: 	    endif
   70: 	    cell+
   71:     repeat
   72:     drop rdrop 0 ;
   73: 
   74: \ !!! nicht optimal!
   75: [IFUNDEF] look
   76: has? ec [IF]
   77: 
   78: has? rom 
   79: [IF]
   80: : prim>name ( xt -- nt flag )
   81:     forth-wordlist @ (look) ;
   82: 
   83: : look
   84:     dup [ unlock rom-dictionary area lock ] 
   85:     literal literal within
   86:     IF
   87: 	>head-noprim dup ?? <>
   88:     ELSE
   89: 	xt>threaded threaded>name
   90:     THEN ;
   91: [ELSE]
   92: : look ( cfa -- lfa flag )
   93:     >head-noprim dup ??? <> ;
   94: [THEN]
   95: 
   96: [ELSE]
   97: 
   98: : PrimStart ['] true >head-noprim ;
   99: 
  100: : prim>name ( xt -- lfa flag )
  101:     PrimStart (look) ;
  102: 
  103: : look ( cfa -- lfa flag )
  104:     dup in-dictionary?
  105:     IF
  106: 	>head-noprim dup ??? <>
  107:     ELSE
  108: 	prim>name
  109:     THEN ;
  110: 
  111: [THEN]
  112: [THEN]
  113: 
  114: : threaded>name ( ca -- lfa flag )
  115:     threaded>xt prim>name ;
  116: 
  117: : >head ( cfa -- nt|0 ) \ gforth to-head
  118:     \G tries to find the name token nt of the word represented by cfa;
  119:     \G returns 0 if it fails.  This word is not absolutely reliable,
  120:     \G it may give false positives and produce wrong nts.
  121:     look and ;
  122: 
  123: ' >head ALIAS >name \ gforth to-name
  124: \G old name of @code{>head}

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