--- gforth/kernel/cond.fs	1998/10/10 10:28:36	1.2
+++ gforth/kernel/cond.fs	2012/08/21 19:36:55	1.27
@@ -1,12 +1,12 @@
 \ Structural Conditionals                              12dec92py
 
-\ Copyright (C) 1995-1997 Free Software Foundation, Inc.
+\ Copyright (C) 1995,1996,1997,2000,2003,2004,2007,2010,2011 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 2
+\ 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,
@@ -15,8 +15,7 @@
 \ 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, write to the Free Software
-\ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+\ along with this program. If not, see http://www.gnu.org/licenses/.
 
 here 0 , \ just a dummy, the real value of locals-list is patched into it in glocals.fs
 AConstant locals-list \ acts like a variable that contains
@@ -48,7 +47,9 @@ variable backedge-locals
 \ locals-list (valid at address) (third)
 
 \ types
-0 constant defstart
+[IFUNDEF] defstart 
+0 constant defstart	\ usally defined in comp.fs
+[THEN]
 1 constant live-orig
 2 constant dead-orig
 3 constant dest \ the loopback branch is always assumed live
@@ -78,20 +79,23 @@ variable backedge-locals
 
 3 constant cs-item-size
 
-: CS-PICK ( ... u -- ... destu ) \ tools-ext
+: CS-PICK ( ... u -- ... destu ) \ tools-ext c-s-pick
  1+ cs-item-size * 1- >r
  r@ pick  r@ pick  r@ pick
  rdrop
  dup non-orig? ;
 
-: CS-ROLL ( destu/origu .. dest0/orig0 u -- .. dest0/orig0 destu/origu ) \ tools-ext
+: CS-ROLL ( destu/origu .. dest0/orig0 u -- .. dest0/orig0 destu/origu ) \ tools-ext c-s-roll
  1+ cs-item-size * 1- >r
  r@ roll r@ roll r@ roll
  rdrop
  dup cs-item? ; 
 
+: CS-DROP ( dest -- ) \ gforth
+    dest? 2drop ;
+
 : cs-push-part ( -- list addr )
- locals-list wordlist-id @ here ;
+ locals-list @ here ;
 
 : cs-push-orig ( -- orig )
  cs-push-part dead-code @
@@ -103,12 +107,17 @@ variable backedge-locals
 
 \ Structural Conditionals                              12dec92py
 
+defer other-control-flow ( -- )
+\ hook for control-flow stuff that's not handled by begin-like etc.
+
 : ?struc      ( flag -- )       abort" unstructured " ;
 : sys?        ( sys -- )        dup 0= ?struc ;
 : >mark ( -- orig )
- cs-push-orig 0 , ;
-: >resolve    ( addr -- )        here over - swap ! ;
-: <resolve    ( addr -- )        here - , ;
+ cs-push-orig 0 , other-control-flow ;
+: >resolve    ( addr -- )
+    here swap !
+    basic-block-end ;
+: <resolve    ( addr -- )        , ;
 
 : BUT
     1 cs-roll ;                      immediate restrict
@@ -124,7 +133,7 @@ variable backedge-locals
  POSTPONE ?branch >mark ; immediate restrict
 
 : ?DUP-IF ( compilation -- orig ; run-time n -- n| ) \ gforth	question-dupe-if
-\G This is the preferred alternative to the idiom "?DUP IF", since it can be
+\G This is the preferred alternative to the idiom "@code{?DUP IF}", since it can be
 \G better handled by tools like stack checkers. Besides, it's faster.
     POSTPONE ?dup-?branch >mark ;       immediate restrict
 
@@ -144,7 +153,7 @@ immediate restrict
 \ people who have not been brought up with Forth (or who have been
 \ brought up with fig-Forth).
 
-: ELSE ( compilation orig1 -- orig2 ; run-time f -- ) \ core
+: ELSE ( compilation orig1 -- orig2 ; run-time -- ) \ core
     POSTPONE ahead
     1 cs-roll
     POSTPONE then ; immediate restrict
@@ -153,7 +162,8 @@ Defer begin-like ( -- )
 ' noop IS begin-like
 
 : BEGIN ( compilation -- dest ; run-time -- ) \ core
-    begin-like cs-push-part dest ; immediate restrict
+    begin-like cs-push-part dest
+    basic-block-end ; immediate restrict
 
 Defer again-like ( dest -- addr )
 ' nip IS again-like
@@ -161,9 +171,10 @@ Defer again-like ( dest -- addr )
 : AGAIN ( compilation dest -- ; run-time -- ) \ core-ext
     dest? again-like  POSTPONE branch  <resolve ; immediate restrict
 
-Defer until-like
-: until, ( list addr xt1 xt2 -- )  drop compile, <resolve drop ;
-' until, IS until-like
+Defer until-like ( list addr xt1 xt2 -- )
+:noname ( list addr xt1 xt2 -- )
+    drop compile, <resolve drop ;
+IS until-like
 
 : UNTIL ( compilation dest -- ; run-time f -- ) \ core
     dest? ['] ?branch ['] ?branch-lp+!# until-like ; immediate restrict
@@ -176,6 +187,16 @@ Defer until-like
     POSTPONE again
     POSTPONE then ; immediate restrict
 
+\ not clear if this should really go into Gforth's kernel...
+
+: CONTINUE ( dest-sys j*sys -- dest-sys j*sys ) \ gforth
+    \g jump to the next outer BEGIN
+    depth 0 ?DO  I pick dest = IF
+	    I cs-item-size / cs-pick postpone AGAIN
+	    LEAVE  THEN
+    cs-item-size +LOOP
+    true abort" no BEGIN found" ; immediate compile-only
+
 \ counted loops
 
 \ leave poses a little problem here
@@ -216,7 +237,7 @@ Avariable leave-sp  leave-stack 3 cells
     leave-sp ! ;
 
 : DONE ( compilation orig -- ; run-time -- ) \ gforth
-    \ !! the original done had ( addr -- )
+    \g resolves all LEAVEs up to the compilaton orig (from a BEGIN)
     drop >r drop
     begin
 	leave>
@@ -296,8 +317,13 @@ Defer exit-like ( -- )
 ' noop IS exit-like
 
 : EXIT ( compilation -- ; run-time nest-sys -- ) \ core
+\G Return to the calling definition; usually used as a way of
+\G forcing an early return from a definition. Before
+\G @code{EXIT}ing you must clean up the return stack and
+\G @code{UNLOOP} any outstanding @code{?DO}...@code{LOOP}s.
     exit-like
     POSTPONE ;s
+    basic-block-end
     POSTPONE unreachable ; immediate restrict
 
 : ?EXIT ( -- ) ( compilation -- ; run-time nest-sys f -- | nest-sys ) \ gforth