\ *****************************************************************************
\ * Copyright (c) 2004, 2008 IBM Corporation
\ * All rights reserved.
\ * This program and the accompanying materials
\ * are made available under the terms of the BSD License
\ * which accompanies this distribution, and is available at
\ * http://www.opensource.org/licenses/bsd-license.php
\ *
\ * Contributors:
\ *     IBM Corporation - initial implementation
\ ****************************************************************************/

: ?offset16 ( -- true|false )
  fcode-offset 16 =
  ;

: ?arch64 ( -- true|false )
  cell 8 =
  ;

: ?bigendian ( -- true|false )
  deadbeef fcode-num !
  fcode-num ?arch64 IF 4 + THEN 
  c@ de =
  ;

: reset-fcode-end ( -- )
  false fcode-end !
  ;

: get-ip ( -- n )
  ip @
  ;

: set-ip ( n -- )
  ip !
  ;

: next-ip ( -- )
  get-ip 1+ set-ip
  ;

: jump-n-ip ( n -- )
  get-ip + set-ip
  ;

: read-byte ( -- n )
  get-ip fcode-rb@
  ;

: ?compile-mode ( -- on|off )
  state @
  ;

: save-evaluator-state
  get-ip               eva-debug? IF ." saved ip "           dup . cr THEN
  fcode-end @          eva-debug? IF ." saved fcode-end "    dup . cr THEN
  fcode-offset         eva-debug? IF ." saved fcode-offset " dup . cr THEN
\ local fcodes are currently NOT saved!
  fcode-spread         eva-debug? IF ." saved fcode-spread " dup . cr THEN  
  ['] fcode@ behavior  eva-debug? IF ." saved fcode@ "       dup . cr THEN
  ;

: restore-evaluator-state
  eva-debug? IF ." restored fcode@ "       dup . cr THEN  to fcode@            
  eva-debug? IF ." restored fcode-spread " dup . cr THEN  to fcode-spread
\ local fcodes are currently NOT restored!
  eva-debug? IF ." restored fcode-offset " dup . cr THEN  to fcode-offset
  eva-debug? IF ." restored fcode-end "    dup . cr THEN  fcode-end !
  eva-debug? IF ." restored ip "           dup . cr THEN  set-ip
  ;

: token-table-index ( fcode# -- addr )
  cells token-table +
  ;

: join-immediate ( xt immediate? addr -- xt+immediate? addr )
  -rot + swap
  ;

: split-immediate ( xt+immediate? -- xt immediate? )
  dup 1 and 2dup - rot drop swap
  ;

: literal, ( n -- )
  postpone literal
  ;

: fc-string,
  postpone sliteral
  dup c, bounds ?do i c@ c, loop
  ;

: set-token ( xt immediate? fcode# -- )
  token-table-index join-immediate !
  ;

: get-token ( fcode# -- xt immediate? )
  token-table-index @ split-immediate
  ;

-1 VALUE break-fcode-addr 
  
: exec ( FCode# -- )
    
   eva-debug? IF
      dup
      get-ip 8 u.r ." : "
      ." [" 3 u.r ." ] "
   THEN
   get-ip break-fcode-addr = IF
	TRUE fcode-end ! drop EXIT
   THEN
   
   get-token 0= IF  \ imm == 0 == false
      ?compile-mode IF
	  compile,
      ELSE
	  eva-debug? IF dup xt>name type space THEN	  
	  execute
      THEN
  ELSE \ immediate
      eva-debug? IF dup xt>name type space THEN
      execute
  THEN
  eva-debug? IF .s cr THEN
  ;

( ---------------------------------------------------- )

0 ?bigendian INCLUDE? big.fs
0 ?bigendian NOT INCLUDE? little.fs

( ---------------------------------------------------- )

: read-fcode# ( -- FCode# )
  read-byte
  dup 01 0F between IF drop read-fcode-num16 THEN
  ;

: read-header ( adr -- )
  next-ip read-byte        drop
  next-ip read-fcode-num16 drop 
  next-ip read-fcode-num32 drop 
  ;

: read-fcode-string ( -- str len )
  read-byte            \ get string length ( -- len )
  next-ip get-ip       \ get string addr   ( -- len str )
  swap                 \ type needs the parameters swapped ( -- str len )
  dup 1- jump-n-ip     \ jump to the end of the string in FCode
  ;

: evaluate-fcode ( -- )
  fcode@ exec              \ read start code
  BEGIN
       next-ip fcode@ exec
       fcode-end @
  UNTIL
  ;

: step-fcode ( -- )
  break-fcode-addr >r -1 to break-fcode-addr      
  fcode@ exec next-ip
  r> to break-fcode-addr   
;    
    
  
( ---------------------------------------------------- )