Initial checkin of the previous GETIN based C64EXPECT etc. which does

call PAUSE during EXPECT and thus runs background tasks during
interactive input.
Downside is the known residue of inverse spaces during backspace,
and the use of undocumented - and therefore changeable (between
Kernal versions) - Kernal variables.
This file is as yet not expected to work when INCLUDEd; it'll at least
need the 6502 assembler loaded, and probably a few more tweaks, before
it can be just loaded from a v4th-x16 system, rather than being
included in a target compile that produces v4th-x16.

6502/C64/src/x16input-tsk.fth

@@ -0,0 +1,84 @@
+
+include vf-lbls-cbm.fth
+
+7f fthpage
+
+\ X16 labels
+
+0ffd2 >label ConOut
+0febd >label KbdbufPeek
+0feab >label ExtApi
+09f2c >label BrdCol
+ 0376 >label BkgPenCol  \ aka color
+ 0381 >label CurFlg  \ aka qtsw
+ 0385 >label InsCnt  \ aka insrt
+
+1 >label RomBank
+0 >label RamBank
+
+  037B >label blnsw  \ C64: $cc
+\   037C >label blnct  \ C64: $cd
+\   037D >label gdbln  \ C64: $ce
+\   037E >label blnon  \ C64: $cf
+\   0262 >label pnt    \ C64: $d1
+\   0380 >label pntr   \ C64: $d3
+\   0373 >label gdcol
+
+\ C64 labels that X16 doesn't have:
+
+\ 028a >label KeyRep  \ aka rptflg
+
+
+\ *** Block No. 129, Hexblock 81
+81 fthpage
+
+\ X16 c64key? getkey
+
+Code c64key? ( -- flag)
+ KbdbufPeek jsr
+ txa  pha
+ Push jmp  end-code
+
+Code getkey  ( -- 8b)
+ GETIN jsr
+ Push0A jmp   end-code
+
+
+\ *** Block No. 130, Hexblock 82
+82 fthpage
+
+\ X16 curon curoff
+
+Code curon   ( --)
+  blnsw stx  Next jmp  end-code
+
+Code curoff   ( --)
+  blnsw sty  Next jmp  end-code
+
+
+\ *** Block No. 131, Hexblock 83
+83 fthpage
+
+( #bs #cr ..keyboard         clv12.4.87)
+
+: c64key  ( -- 8b)
+ curon BEGIN pause c64key?  UNTIL
+ curoff getkey ;
+
+14 Constant #bs   0D Constant #cr
+
+: c64decode
+ ( addr cnt1 key -- addr cnt2)
+  #bs case?  IF  dup  IF del 1- THEN
+                            exit  THEN
+  #cr case?  IF  dup span ! exit THEN
+  >r  2dup +  r@ swap c!  r> emit  1+ ;
+
+: c64expect ( addr len1 -- )
+ span !  0
+ BEGIN  dup span @  u<
+ WHILE  key  decode
+ REPEAT 2drop space ;
+
+Input: keyboard-pause   [ here input ! ]
+ c64key c64key? c64decode c64expect ;