editor: add edit buffer

Also, add word "C!+" and fix PSP leak in FILL.

blk/050

@@ -7,6 +7,7 @@ Memory
 C@       a -- c          Set c to byte at address a
 C@+      a -- a+1 c      Fetch c from a and inc a.
 C!       c a --          Store byte c in address a
+C!+      c a -- a+1      Store byte c in a and inc a.
 CURRENT  -- a            Set a to wordref of last added entry.
 CURRENT* -- a            A pointer to active CURRENT*. Useful
                          when we have multiple active dicts.

blk/104

@@ -1,5 +1,6 @@
 ( Cursor position in buffer. EDPOS/64 is line number )
 VARIABLE EDPOS
+CREATE EDBUF 64 ALLOT
 : _cpos BLK( + ;
 : _lpos 64 * _cpos ;
 : _pln ( lineno -- )
@@ -7,7 +8,9 @@ VARIABLE EDPOS
         I EDPOS @ _cpos = IF '^' EMIT THEN
         I C@ DUP 0x20 < IF DROP 0x20 THEN
         EMIT
-    LOOP ( lno )
-    1+ . ;
-( user-facing lines are 1-based )
-: T 1- DUP 64 * EDPOS ! _pln ;
+    LOOP ( lno ) 1+ . ;
+: _zbuf EDBUF 64 0 FILL ;
+: _type ( -- )
+    C< DUP 0xd = IF DROP EXIT THEN _zbuf EDBUF BEGIN ( c a )
+        C!+ C< SWAP OVER 0x0d = UNTIL ( c a )
+    2DROP ;

blk/105

@@ -1,16 +1,7 @@
-: P
-    EDPOS @ _cpos C<
-    64 0 DO ( bpos c )
-        DUP 0xd = IF DROP 0 THEN
-        2DUP SWAP I + C!
-        DUP IF DROP C< THEN
-    LOOP
-    2DROP
-    BLK!!
-;
-
+( user-facing lines are 1-based )
+: T 1- DUP 64 * EDPOS ! _pln ;
+: P _type EDBUF EDPOS @ _cpos 64 MOVE BLK!! ;
 : _mvln+ ( ln -- move ln 1 line further )
     DUP 14 > IF DROP EXIT THEN
     _lpos DUP 64 + 64 MOVE
 ;
-

blk/155

@@ -1,6 +1,4 @@
 : FILL ( a n b -- )
     SWAP 2 PICK + ( a b a+n ) ROT ( b a+n a ) DO ( b )
         DUP I C!
-    LOOP
-;
-
+    LOOP DROP ;

blk/436

@@ -10,3 +10,5 @@
 
 ( a -- a+1 c )
 : C@+ DUP C@ SWAP 1+ SWAP ;
+( c a -- a+1 )
+: C!+ SWAP OVER C! 1+ ;