xcomp: widen scope

We can now cross-compile core.fs.

emul/forth/xcomp.fs

@@ -1,11 +1,20 @@
+: _
+    ['] EXIT ,
+    R> DROP     ( exit : )
+    XCOFF
+; IMMEDIATE
+';' CURRENT @ 4 - C!
+
+: (find) (xfind) ;
+: ['] X['] ; IMMEDIATE
+: COMPILE XCOMPILE ; IMMEDIATE
 : CODE XCODE ;
 : IMMEDIATE XIMM ;
 : : [ ' X: , ] ;
 
 CURRENT @ XCURRENT !
-H@ ' _bend - 4 + XOFF !
 
 ( dummy entry for dict hook )
 (xentry) _
 H@ 256 /MOD 2 PC! 2 PC!
-
+H@ ' _bend - XOFF !

forth/xcomp.fs

@@ -14,18 +14,29 @@
   "'" and friends will *not* find words you're about to
   define. Only (xfind) will.
 
-  Words ":", "IMMEDIATE" and "CODE" are not automatically
-  shadowed to allow the harmless inclusion of this unit. This
-  shadowing has to take place in your xcomp configuration.
+  Words overrides like ":", "IMMEDIATE" and "CODE" are not
+  automatically shadowed to allow the harmless inclusion of
+  this unit. This shadowing has to take place in your xcomp
+  configuration.
 
   See example in /emul/forth/xcomp.fs
+
+  Note that this cross compilation unit is far from foolproof
+  and cannot cross compile any kind of code. Cross compliation
+  of Forth dicts is *tricky*. This unit is designed to cross
+  compile the core full interpreter, that is, the contents
+  of the "/forth" folder of the project.
+
+  Cross compiling anything else might work, but as soon as
+  you start defining immediates and using them on-the-fly,
+  things get icky.
 )
 
 VARIABLE XCURRENT
 VARIABLE XOFF
 
 : XCON XCURRENT CURRENT* ! ;
-: XCOFF CURRENT CURRENT* ! ;
+: XCOFF 0x02 RAM+ CURRENT* ! ;
 
 : (xentry) XCON (entry) XCOFF ;
 
@@ -33,15 +44,37 @@ VARIABLE XOFF
 
 : XIMM XCON IMMEDIATE XCOFF ;
 
+: XAPPLY
+    DUP XOFF @ > IF XOFF @ - THEN
+;
+
+( Run find in XCURRENT and apply XOFF )
+: (xfind)
+    XCURRENT @ SWAP     ( xcur w )
+    _find               ( a f )
+    IF  ( a )
+        ( apply XOFF )
+        XAPPLY 1
+    ELSE
+        0
+    THEN
+;
+
+: X' XCON ' XCOFF XAPPLY ;
+: X['] X' LITN ;
+( TODO: am I making the word "," stable here? )
+: XCOMPILE X' LITN ['] , , ;
+
 : X:
-    XCON
-    (entry)
+    (xentry)
     ( 0e == compiledWord )
     [ 0x0e LITN ] ,
     BEGIN
     ( DUP is because we need a copy in case it's IMMED )
     WORD DUP
-    (find)      ( w a f )
+    ( cross compile CURRENT )
+    XCURRENT @ SWAP     ( w xcur w )
+    _find               ( w a f )
     IF
         ( is word )
         DUP IMMED?
@@ -49,16 +82,16 @@ VARIABLE XOFF
             ( When encountering IMMEDIATE, we exec the *host*
               word. )
             DROP    ( w )
-            ( hardcoded system CURRENT )
+            ( system CURRENT )
             0x02 RAM+ @ SWAP        ( cur w )
             _find                   ( a f )
             NOT IF ABORT THEN   ( a )
-            EXECUTE
+            XCON EXECUTE XCOFF
         ELSE
             ( not an immed. drop backup w and write, with
               offset. )
             SWAP DROP   ( a )
-            DUP 0x100 > IF XOFF @ - THEN
+            XAPPLY
             ,
         THEN
     ELSE ( w a )
@@ -67,5 +100,4 @@ VARIABLE XOFF
         (parse*) @ EXECUTE LITN
     THEN
     AGAIN
-    XCOFF
 ;