11 \ Allow for slightly more portable code
14 \ Since the smallest unit of memory in our system is 64 bits and since strings
15 \ are stored as arrays of 64 bit integers, the character store/fetch words are
16 \ just aliases of the standard store/fetch words.
21 : DEPTH PSP@ PSP0 @ - ;
26 : LITERAL IMMEDIATE ['] LIT , , ;
28 : ':' [ CHAR : ] LITERAL ;
29 : ';' [ CHAR ; ] LITERAL ;
30 : '(' [ CHAR ( ] LITERAL ;
31 : ')' [ CHAR ) ] LITERAL ;
32 : '<' [ CHAR < ] LITERAL ;
33 : '>' [ CHAR > ] LITERAL ;
34 : '"' [ CHAR " ] LITERAL ;
35 : 'A' [ CHAR A ] LITERAL ;
36 : '0' [ CHAR 0 ] LITERAL ;
37 : '-' [ CHAR - ] LITERAL ;
38 : '.' [ CHAR . ] LITERAL ;
44 WORD \ get the next word
45 FIND \ find it in the dictionary
46 >CFA \ get its codeword
51 LATEST @ \ LATEST points to the word being compiled at the moment
52 >CFA \ get the codeword
56 : DEBUGON TRUE DEBUG ! ;
57 : DEBUGOFF FALSE DEBUG ! ;
59 \ CONTROL STRUCTURES ----------------------------------------------------------------------
62 ['] 0BRANCH , \ compile 0BRANCH
63 HERE @ \ save location of the offset on the stack
64 0 , \ compile a dummy offset
69 HERE @ SWAP - \ calculate the offset from the address saved on the stack
70 SWAP ! \ store the offset in the back-filled location
74 ['] BRANCH , \ definite branch to just over the false-part
75 HERE @ \ save location of the offset on the stack
76 0 , \ compile a dummy offset
77 SWAP \ now back-fill the original (IF) offset
78 DUP \ same as for THEN word above
84 HERE @ \ save location on the stack
88 ['] 0BRANCH , \ compile 0BRANCH
89 HERE @ - \ calculate the offset from the address saved on the stack
90 , \ compile the offset here
94 ['] BRANCH , \ compile BRANCH
95 HERE @ - \ calculate the offset back
96 , \ compile the offset here
100 ['] 0BRANCH , \ compile 0BRANCH
101 HERE @ \ save location of the offset2 on the stack
102 0 , \ compile a dummy offset2
106 ['] BRANCH , \ compile BRANCH
107 SWAP \ get the original offset (from BEGIN)
108 HERE @ - , \ and compile it after BRANCH
110 HERE @ SWAP - \ calculate the offset2
111 SWAP ! \ and back-fill it in the original location
115 ['] NOT , \ compile NOT (to reverse the test)
116 [COMPILE] IF \ continue by calling the normal IF
120 ['] LIT , -1 , [COMPILE] IF
122 ['] LIT , HERE @ 0 , ['] >R ,
127 ['] 2DUP , ['] - , [COMPILE] IF
129 ['] LIT , HERE @ 0 , ['] >R ,
139 ['] R> , ['] RDROP , ['] RDROP ,
140 ['] LIT , HERE @ 7 + , ['] DUP , ['] -ROT , ['] - , ['] SWAP , ['] ! ,
151 ['] DUP , \ Store copy of increment
153 ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] + , ['] 2DUP , ['] - ,
154 ['] SWAP , ['] >R , ['] SWAP , ['] >R , ['] SWAP , ['] >R ,
156 \ Condition differently depending on sign of increment
157 ['] SWAP , ['] 0>= , [COMPILE] IF
163 \ Branch back to begining of loop kernel
164 ['] 0BRANCH , HERE @ - ,
167 ['] RDROP , ['] RDROP , ['] RDROP ,
169 \ Record address of loop end for any LEAVEs to use
173 ['] 2DROP , \ Clean up if loop was entirely skipped (?DO)
183 \ CASE ------------------------------------------------------------------------
186 0 \ push 0 to mark the bottom of the stack
190 ['] OVER , \ compile OVER
192 [COMPILE] IF \ compile IF
193 ['] DROP , \ compile DROP
197 [COMPILE] ELSE \ ENDOF is the same as ELSE
201 ['] DROP , \ compile DROP
203 \ keep compiling THEN until we get to our zero marker
212 \ COMMENTS ----------------------------------------------------------------------
215 1 \ allowed nested parens by keeping track of depth
217 KEY \ read next character
218 DUP '(' = IF \ open paren?
219 DROP \ drop the open paren
222 ')' = IF \ close paren?
226 DUP 0= UNTIL \ continue until we reach matching close paren, depth 0
227 DROP \ drop the depth counter
230 ( Some more complicated stack examples, showing the stack notation. )
231 : NIP ( x y -- y ) SWAP DROP ;
232 : TUCK ( x y -- y x y ) DUP -ROT ;
233 : PICK ( x_u ... x_1 x_0 u -- x_u ... x_1 x_0 x_u )
234 1+ ( add one because of 'u' on the stack )
235 PSP@ SWAP - ( add to the stack pointer )
238 : ROLL ( x_u x_u-1... x_0 u -- x_u-1 ... x_0 x_u )
239 1+ DUP PICK SWAP ( x_u x_u-1 ... x_0 x_u u+1 )
240 PSP@ 1- SWAP - PSP@ 2- SWAP
247 ( With the looping constructs, we can now write SPACES, which writes n spaces to stdout. )
256 ( Standard words for manipulating BASE. )
257 : DECIMAL ( -- ) 10 BASE ! ;
258 : HEX ( -- ) 16 BASE ! ;
260 ( Compute absolute value. )
283 ( PRINTING NUMBERS ---------------------------------------------------------------------- )
285 ( This is the underlying recursive definition of U. )
287 BASE @ /MOD ( width rem quot )
288 ?DUP IF ( if quotient <> 0 then )
289 RECURSE ( print the quotient )
292 ( print the remainder )
294 '0' ( decimal digits 0..9 )
296 10 - ( hex and beyond digits A..Z )
303 ( This word returns the width (in characters) of an unsigned number in the current base )
304 : UWIDTH ( u -- width )
305 BASE @ / ( rem quot )
306 ?DUP IF ( if quotient <> 0 then )
307 RECURSE 1+ ( return 1+recursive call )
316 UWIDTH ( width u uwidth )
317 ROT ( u uwidth width )
318 SWAP - ( u width-uwidth )
319 ( At this point if the requested width is narrower, we'll have a negative number on the stack.
320 Otherwise the number on the stack is the number of spaces to print. But SPACES won't print
321 a negative number of spaces anyway, so it's now safe to call SPACES ... )
323 ( ... and then call the underlying implementation of U. )
331 1 ( save a flag to remember that it was negative | width n 1 )
340 SWAP ( flag width u )
341 DUP ( flag width u u )
342 UWIDTH ( flag width u uwidth )
343 ROT ( flag u uwidth width )
344 SWAP - ( flag u width-uwidth )
349 IF ( was it negative? print the - character )
359 '<' EMIT DEPTH U. '>' EMIT SPACE
372 ( ? fetches the integer at an address and prints it. )
373 : ? ( addr -- ) @ . ;
375 ( c a b WITHIN returns true if a <= c and c < b )
392 ( STRINGS ---------------------------------------------------------------------- )
395 ( Block copy, however, is important and novel: )
396 : CMOVE ( src dest length -- )
402 -ROT OVER - ( length src (dest-src) )
403 -ROT DUP ROT + SWAP ( (dest-src) (src+length) src )
406 I @ ( (dest-src) i@ )
407 OVER I + ( (dest-src) i@ (dest-src+i) )
414 ( C, appends a byte to the current compiled word. )
420 : S" IMMEDIATE ( -- addr len )
421 STATE @ IF ( compiling? )
422 ['] LITSTRING , ( compile LITSTRING )
423 HERE @ ( save the address of the length word on the stack )
424 0 , ( dummy length - we don't know what it is yet )
427 KEY ( get next character of the string )
430 C, ( copy character )
432 DROP ( drop the double quote character at the end )
433 DUP ( get the saved address of the length word )
434 HERE @ SWAP - ( calculate the length )
435 1- ( subtract 1 (because we measured from the start of the length word) )
436 SWAP ! ( and back-fill the length location )
437 ELSE ( immediate mode )
438 HERE @ ( get the start address of the temporary space )
444 OVER C! ( save next character )
445 1+ ( increment address )
447 DROP ( drop the final " character )
448 HERE @ - ( calculate the length )
449 HERE @ ( push the start address )
454 : ." IMMEDIATE ( -- )
455 [COMPILE] S" ( read the string, and compile LITSTRING, etc. )
456 ['] TELL , ( compile the final TELL )
464 DROP ( drop the double quote character )
465 EXIT ( return from this function )
472 ( CONSTANTS AND VARIABLES ------------------------------------------------------ )
475 WORD HEADER ( make dictionary entry (the name follows CONSTANT) )
476 DOCOL , ( append DOCOL (the codeword field of this word) )
477 ['] LIT , ( append the codeword LIT )
478 , ( append the value on the top of the stack )
479 ['] EXIT , ( append the codeword EXIT )
483 HERE +! ( adds n to HERE, after this the old value of HERE is still on the stack )
488 1 CELLS ALLOT ( allocate 1 cell of memory, push the pointer to this memory )
493 WORD HEADER ( make the dictionary entry (the name follows VALUE) )
494 DOCOL , ( append DOCOL )
495 ['] LIT , ( append the codeword LIT )
496 , ( append the initial value )
497 ['] EXIT , ( append the codeword EXIT )
500 : TO IMMEDIATE ( n -- )
501 WORD ( get the name of the value )
502 FIND ( look it up in the dictionary )
503 >DFA ( get a pointer to the first data field (the 'LIT') )
504 1+ ( increment to point at the value )
505 STATE @ IF ( compiling? )
506 ['] LIT , ( compile LIT )
507 , ( compile the address of the value )
508 ['] ! , ( compile ! )
509 ELSE ( immediate mode )
510 ! ( update it straightaway )
514 ( x +TO VAL adds x to VAL )
516 WORD ( get the name of the value )
517 FIND ( look it up in the dictionary )
518 >DFA ( get a pointer to the first data field (the 'LIT') )
519 1+ ( increment to point at the value )
520 STATE @ IF ( compiling? )
521 ['] LIT , ( compile LIT )
522 , ( compile the address of the value )
523 ['] +! , ( compile +! )
524 ELSE ( immediate mode )
525 +! ( update it straightaway )
529 ( Fill u ints, starting at a, with the value b )
541 ( PRINTING THE DICTIONARY ------------------------------------------------------ )
544 1+ ( skip over the link pointer )
545 DUP @ ( get the flags/length byte )
546 F_LENMASK AND ( mask out the flags - just want the length )
549 DUP 0> ( length > 0? )
551 SWAP 1+ ( addr len -- len addr+1 )
552 DUP @ ( len addr -- len addr char | get the next character)
553 DUP 32 >= OVER 127 <= AND IF
554 EMIT ( len addr char -- len addr | and print it)
560 SWAP 1- ( len addr -- addr len-1 | subtract one from length )
562 2DROP ( len addr -- )
566 1+ ( skip over the link pointer )
567 @ ( get the flags/length byte )
568 F_HIDDEN AND ( mask the F_HIDDEN flag and return it (as a truth value) )
571 1+ ( skip over the link pointer )
572 @ ( get the flags/length byte )
573 F_IMMED AND ( mask the F_IMMED flag and return it (as a truth value) )
577 LATEST @ ( start at LATEST dictionary entry )
579 ?DUP ( while link pointer is not null )
581 DUP ?HIDDEN NOT IF ( ignore hidden words )
582 DUP ID. ( but if not hidden, print the word )
585 @ ( dereference the link pointer - go to previous word )
591 ( FORGET ---------------------------------------------------------------------- )
594 WORD FIND ( find the word, gets the dictionary entry address )
595 DUP @ LATEST ! ( set LATEST to point to the previous word )
596 HERE ! ( and store HERE with the dictionary address )
599 ( DUMP ------------------------------------------------------------------------ )
604 ( DECOMPILER ------------------------------------------------------------------ )
607 LATEST @ ( start at LATEST dictionary entry )
609 ?DUP ( while link pointer is not null )
611 2DUP SWAP ( cfa curr curr cfa )
612 < IF ( current dictionary entry < cfa? )
613 NIP ( leave curr dictionary entry on the stack )
616 @ ( follow link pointer back )
618 DROP ( restore stack )
619 0 ( sorry, nothing found )
623 WORD FIND ( find the dictionary entry to decompile )
625 ( Now we search again, looking for the next word in the dictionary. This gives us
626 the length of the word that we will be decompiling. (Well, mostly it does). )
627 HERE @ ( address of the end of the last compiled word )
628 LATEST @ ( word last curr )
630 2 PICK ( word last curr word )
631 OVER ( word last curr word curr )
632 <> ( word last curr word<>curr? )
633 WHILE ( word last curr )
635 DUP @ ( word curr prev (which becomes: word last curr) )
638 DROP ( at this point, the stack is: start-of-word end-of-word )
639 SWAP ( end-of-word start-of-word )
644 ':' EMIT SPACE DUP ID. SPACE
645 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN CR
648 \ Variable definition
649 ." Variable " DUP ID. CR
653 \ Constant definition
654 ." Constant " DUP ID. CR
659 ." Primitive or word with unrecognized codeword." CR
663 ( begin the definition with : NAME [IMMEDIATE] )
664 ( ':' EMIT SPACE DUP ID. SPACE
665 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN CR 4 )
669 >DFA ( get the data address, ie. points after DOCOL | end-of-word start-of-data )
671 ( now we start decompiling until we hit the end of the word )
675 DUP @ ( end start codeword )
678 ['] LIT OF ( is it LIT ? )
679 1+ DUP @ ( get next word which is the integer constant )
682 ['] LITSTRING OF ( is it LITSTRING ? )
683 [ CHAR S ] LITERAL EMIT '"' EMIT SPACE ( print S"<space> )
684 1+ DUP @ ( get the length word )
685 SWAP 1+ SWAP ( end start+1 length )
686 2DUP TELL ( print the string )
687 '"' EMIT SPACE ( finish the string with a final quote )
688 + ( end start+1+len, aligned )
689 1- ( because we're about to add 4 below )
691 ['] 0BRANCH OF ( is it 0BRANCH ? )
693 1+ DUP @ ( print the offset )
697 ['] BRANCH OF ( is it BRANCH ? )
699 1+ DUP @ ( print the offset )
703 ['] ['] OF ( is it ['] ? )
705 1+ DUP @ ( get the next codeword )
706 CFA> ( and force it to be printed as a dictionary entry )
709 ['] EXIT OF ( is it EXIT? )
710 ( We expect the last word to be EXIT, and if it is then we don't print it
711 because EXIT is normally implied by ;. EXIT can also appear in the middle
712 of words, and then it needs to be printed. )
713 2DUP ( end start end start )
714 1+ ( end start end start+1 )
715 <> IF ( end start | we're not at the end )
720 DUP ( in the default case we always need to DUP before using )
721 CFA> ( look up the codeword to get the dictionary entry )
722 ID. SPACE ( and print it )
730 2DROP ( restore stack )
734 ( MEMORY ------------------------------------------------------------------ )
736 : UNUSED ( -- cells )