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Diff for /gforth/kernel/int.fs between versions 1.181 and 1.182

version 1.181, 2011/11/11 18:29:10 version 1.182, 2011/11/13 20:54:56
Line 448  const Create ???  0 , 3 , char ? c, char Line 448  const Create ???  0 , 3 , char ? c, char
   
 : head? ( addr -- f )  : head? ( addr -- f )
 \G heuristic check whether addr is a name token; may deliver false  \G heuristic check whether addr is a name token; may deliver false
 \G positives; addr must be a valid address; returns 1 for  \G positives; addr must be a valid address
 \G particularly unsafe positives      dup dup aligned <>
     \ we follow the link fields and check for plausibility; two      if
     \ iterations should catch most false addresses: on the first          drop false exit \ heads are aligned
     \ iteration, we may get an xt, on the second a code address (or      then
     \ some code), which is typically not in the dictionary.      name>string dup $1F > if
     \ we added a third iteration for working with code and ;code words.          2drop false exit \ realistically the name is short
     3 0 do      then
         dup dup aligned <> if \ protect @ against unaligned accesses      + cfaligned @ here forthstart within ; \ and the cfa is outside
             drop false unloop exit  
         then  
         dup @ dup  
         if ( addr addr1 )  
             dup rot forthstart within  
             if \ addr1 is outside forthstart..addr, not a head  
                 drop false unloop exit  
             then ( addr1 )  
         else \ 0 in the link field, no further checks  
             2drop 1 unloop exit \ this is very unsure, so return 1  
         then  
     loop  
     \ in dubio pro:  
     drop true ;  
   
 : >head-noprim ( cfa -- nt ) \ gforth  to-head-noprim  : >head-noprim ( cfa -- nt ) \ gforth  to-head-noprim
     \ also heuristic      \ also heuristic
Removed from v.1.181  
changed lines
  Added in v.1.182

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