4 ; \ We can now comment!
6 \ BASIC DEFINITIONS ----------------------------------------------------------------------
18 \ Translate a number of cells into memory units
19 \ (in our case 1 cell = 1 memory unit)
22 \ Since the smallest unit of memory in our system is 64 bits and since strings
23 \ are stored as arrays of 64 bit integers, the character store/fetch words are
24 \ just aliases of the standard store/fetch words.
29 : DEPTH PSP@ PSP0 @ - ;
34 : LITERAL IMMEDIATE ['] LIT , , ;
50 BL WORD \ get the next word
51 FIND \ find it in the dictionary
52 >CFA \ get its codeword
57 LATEST @ \ LATEST points to the word being compiled at the moment
58 >CFA \ get the codeword
62 : DEBUGON TRUE DEBUG ! ;
63 : DEBUGOFF FALSE DEBUG ! ;
65 \ CONTROL STRUCTURES ----------------------------------------------------------------------
68 ['] 0BRANCH , \ compile 0BRANCH
69 HERE @ \ save location of the offset on the stack
70 0 , \ compile a dummy offset
75 HERE @ SWAP - \ calculate the offset from the address saved on the stack
76 SWAP ! \ store the offset in the back-filled location
80 ['] BRANCH , \ definite branch to just over the false-part
81 HERE @ \ save location of the offset on the stack
82 0 , \ compile a dummy offset
83 SWAP \ now back-fill the original (IF) offset
84 DUP \ same as for THEN word above
90 HERE @ \ save location on the stack
94 ['] 0BRANCH , \ compile 0BRANCH
95 HERE @ - \ calculate the offset from the address saved on the stack
96 , \ compile the offset here
100 ['] BRANCH , \ compile BRANCH
101 HERE @ - \ calculate the offset back
102 , \ compile the offset here
106 ['] 0BRANCH , \ compile 0BRANCH
107 HERE @ \ save location of the offset2 on the stack
108 0 , \ compile a dummy offset2
112 ['] BRANCH , \ compile BRANCH
113 SWAP \ get the original offset (from BEGIN)
114 HERE @ - , \ and compile it after BRANCH
116 HERE @ SWAP - \ calculate the offset2
117 SWAP ! \ and back-fill it in the original location
121 ['] NOT , \ compile NOT (to reverse the test)
122 [COMPILE] IF \ continue by calling the normal IF
126 ['] LIT , -1 , [COMPILE] IF
128 ['] LIT , HERE @ 0 , ['] >R ,
133 ['] 2DUP , ['] - , [COMPILE] IF
135 ['] LIT , HERE @ 0 , ['] >R ,
145 ['] R> , ['] RDROP , ['] RDROP ,
146 ['] LIT , HERE @ 7 + , ['] DUP , ['] -ROT , ['] - , ['] SWAP , ['] ! ,
157 ['] DUP , \ Store copy of increment
159 ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] + , ['] 2DUP , ['] - ,
160 ['] SWAP , ['] >R , ['] SWAP , ['] >R , ['] SWAP , ['] >R ,
162 \ Condition differently depending on sign of increment
163 ['] SWAP , ['] 0>= , [COMPILE] IF
169 \ Branch back to begining of loop kernel
170 ['] 0BRANCH , HERE @ - ,
173 ['] RDROP , ['] RDROP , ['] RDROP ,
175 \ Record address of loop end for any LEAVEs to use
179 ['] 2DROP , \ Clean up if loop was entirely skipped (?DO)
189 \ CASE ------------------------------------------------------------------------
192 0 \ push 0 to mark the bottom of the stack
196 ['] OVER , \ compile OVER
198 [COMPILE] IF \ compile IF
199 ['] DROP , \ compile DROP
203 [COMPILE] ELSE \ ENDOF is the same as ELSE
207 ['] DROP , \ compile DROP
209 \ keep compiling THEN until we get to our zero marker
218 \ COMMENTS ----------------------------------------------------------------------
221 1 \ allowed nested parens by keeping track of depth
223 >IN #TIB >= IF \ End of TIB?
224 QUERY \ Get next line
228 DUP [CHAR] ( = IF \ open paren?
229 DROP \ drop the open paren
232 [CHAR] ) = IF \ close paren?
236 DUP 0= UNTIL \ continue until we reach matching close paren, depth 0
237 DROP \ drop the depth counter
240 ( Some more complicated stack examples, showing the stack notation. )
241 : NIP ( x y -- y ) SWAP DROP ;
242 : TUCK ( x y -- y x y ) DUP -ROT ;
243 : PICK ( x_u ... x_1 x_0 u -- x_u ... x_1 x_0 x_u )
244 1+ ( add one because of 'u' on the stack )
245 PSP@ SWAP - ( add to the stack pointer )
248 : ROLL ( x_u x_u-1... x_0 u -- x_u-1 ... x_0 x_u )
249 1+ DUP PICK SWAP ( x_u x_u-1 ... x_0 x_u u+1 )
250 PSP@ 1- SWAP - PSP@ 2- SWAP
257 ( With the looping constructs, we can now write SPACES, which writes n spaces to stdout. )
266 ( Standard words for manipulating BASE. )
267 : DECIMAL ( -- ) 10 BASE ! ;
268 : HEX ( -- ) 16 BASE ! ;
270 ( Compute absolute value. )
293 ( PRINTING NUMBERS ---------------------------------------------------------------------- )
295 ( This is the underlying recursive definition of U. )
297 BASE @ /MOD ( width rem quot )
298 ?DUP IF ( if quotient <> 0 then )
299 RECURSE ( print the quotient )
302 ( print the remainder )
304 [CHAR] 0 ( decimal digits 0..9 )
306 10 - ( hex and beyond digits A..Z )
313 ( This word returns the width (in characters) of an unsigned number in the current base )
314 : UWIDTH ( u -- width )
315 BASE @ / ( rem quot )
316 ?DUP IF ( if quotient <> 0 then )
317 RECURSE 1+ ( return 1+recursive call )
326 UWIDTH ( width u uwidth )
327 ROT ( u uwidth width )
328 SWAP - ( u width-uwidth )
329 ( At this point if the requested width is narrower, we'll have a negative number on the stack.
330 Otherwise the number on the stack is the number of spaces to print. But SPACES won't print
331 a negative number of spaces anyway, so it's now safe to call SPACES ... )
333 ( ... and then call the underlying implementation of U. )
341 1 ( save a flag to remember that it was negative | width n 1 )
350 SWAP ( flag width u )
351 DUP ( flag width u u )
352 UWIDTH ( flag width u uwidth )
353 ROT ( flag u uwidth width )
354 SWAP - ( flag u width-uwidth )
359 IF ( was it negative? print the - character )
369 [CHAR] < EMIT DEPTH U. [CHAR] > EMIT SPACE
382 ( ? fetches the integer at an address and prints it. )
383 : ? ( addr -- ) @ . ;
385 ( c a b WITHIN returns true if a <= c and c < b )
402 ( STRINGS ---------------------------------------------------------------------- )
405 ( Block copy, however, is important and novel: )
406 : CMOVE ( src dest length -- )
412 -ROT OVER - ( length src (dest-src) )
413 -ROT DUP ROT + SWAP ( (dest-src) (src+length) src )
416 I @ ( (dest-src) i@ )
417 OVER I + ( (dest-src) i@ (dest-src+i) )
424 ( C, appends a byte to the current compiled word. )
430 : S" IMMEDIATE ( -- addr len )
431 STATE @ IF ( compiling? )
432 ['] LITSTRING , ( compile LITSTRING )
433 HERE @ ( save the address of the length word on the stack )
434 0 , ( dummy length - we don't know what it is yet )
437 KEY ( get next character of the string )
440 C, ( copy character )
442 DROP ( drop the double quote character at the end )
443 DUP ( get the saved address of the length word )
444 HERE @ SWAP - ( calculate the length )
445 1- ( subtract 1 (because we measured from the start of the length word) )
446 SWAP ! ( and back-fill the length location )
447 ELSE ( immediate mode )
448 HERE @ ( get the start address of the temporary space )
454 OVER C! ( save next character )
455 1+ ( increment address )
457 DROP ( drop the final " character )
458 HERE @ - ( calculate the length )
459 HERE @ ( push the start address )
464 : ." IMMEDIATE ( -- )
465 [COMPILE] S" ( read the string, and compile LITSTRING, etc. )
466 ['] TYPE , ( compile the final TYPE )
474 DROP ( drop the double quote character )
475 EXIT ( return from this function )
481 ( Converts address of counted string into address of
482 start of string and length of string. )
483 : COUNT ( addr1 -- addr2 n )
487 ( CONSTANTS AND VARIABLES ------------------------------------------------------ )
490 BL WORD HEADER ( make dictionary entry (the name follows CONSTANT) )
491 DOCOL , ( append DOCOL (the codeword field of this word) )
492 ['] LIT , ( append the codeword LIT )
493 , ( append the value on the top of the stack )
494 ['] EXIT , ( append the codeword EXIT )
498 HERE +! ( adds n to HERE, after this the old value of HERE is still on the stack )
503 1 CELLS ALLOT ( allocate 1 cell of memory, push the pointer to this memory )
508 BL WORD HEADER ( make the dictionary entry (the name follows VALUE) )
509 DOCOL , ( append DOCOL )
510 ['] LIT , ( append the codeword LIT )
511 , ( append the initial value )
512 ['] EXIT , ( append the codeword EXIT )
515 : TO IMMEDIATE ( n -- )
516 BL WORD ( get the name of the value )
517 FIND ( look it up in the dictionary )
518 >PFA ( 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 ( x +TO VAL adds x to VAL )
531 BL WORD ( get the name of the value )
532 FIND ( look it up in the dictionary )
533 >PFA ( get a pointer to the first data field (the 'LIT') )
534 1+ ( increment to point at the value )
535 STATE @ IF ( compiling? )
536 ['] LIT , ( compile LIT )
537 , ( compile the address of the value )
538 ['] +! , ( compile +! )
539 ELSE ( immediate mode )
540 +! ( update it straightaway )
544 ( Fill u ints, starting at a, with the value b )
556 ( PRINTING THE DICTIONARY ------------------------------------------------------ )
559 1+ ( skip over the link pointer )
560 DUP @ ( get the flags/length byte )
561 F_LENMASK AND ( mask out the flags - just want the length )
564 DUP 0> ( length > 0? )
566 SWAP 1+ ( addr len -- len addr+1 )
567 DUP @ ( len addr -- len addr char | get the next character)
568 DUP 32 >= OVER 127 <= AND IF
569 EMIT ( len addr char -- len addr | and print it)
575 SWAP 1- ( len addr -- addr len-1 | subtract one from length )
577 2DROP ( len addr -- )
581 1+ ( skip over the link pointer )
582 @ ( get the flags/length byte )
583 F_HIDDEN AND ( mask the F_HIDDEN flag and return it (as a truth value) )
586 1+ ( skip over the link pointer )
587 @ ( get the flags/length byte )
588 F_IMMED AND ( mask the F_IMMED flag and return it (as a truth value) )
592 LATEST @ ( start at LATEST dictionary entry )
594 ?DUP ( while link pointer is not null )
596 DUP ?HIDDEN NOT IF ( ignore hidden words )
597 DUP ID. ( but if not hidden, print the word )
600 @ ( dereference the link pointer - go to previous word )
606 ( FORGET ---------------------------------------------------------------------- )
609 BL WORD FIND ( find the word, gets the dictionary entry address )
610 DUP @ LATEST ! ( set LATEST to point to the previous word )
611 HERE ! ( and store HERE with the dictionary address )
614 ( DUMP ------------------------------------------------------------------------ )
619 ( DECOMPILER ------------------------------------------------------------------ )
622 LATEST @ ( start at LATEST dictionary entry )
624 ?DUP ( while link pointer is not null )
626 2DUP SWAP ( cfa curr curr cfa )
627 < IF ( current dictionary entry < cfa? )
628 NIP ( leave curr dictionary entry on the stack )
631 @ ( follow link pointer back )
633 DROP ( restore stack )
634 0 ( sorry, nothing found )
638 BL WORD 2DUP FIND ( find the dictionary entry to decompile )
641 ." Word '" TYPE ." ' not found in dictionary."
647 ( Now we search again, looking for the next word in the dictionary. This gives us
648 the length of the word that we will be decompiling. (Well, mostly it does). )
649 HERE @ ( address of the end of the last compiled word )
650 LATEST @ ( word last curr )
652 2 PICK ( word last curr word )
653 OVER ( word last curr word curr )
654 <> ( word last curr word<>curr? )
655 WHILE ( word last curr )
657 DUP @ ( word curr prev (which becomes: word last curr) )
660 DROP ( at this point, the stack is: start-of-word end-of-word )
661 SWAP ( end-of-word start-of-word )
666 [CHAR] : EMIT SPACE DUP ID. SPACE
667 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN CR
670 \ Variable definition
671 ." Variable " DUP ID. CR
675 \ Constant definition
676 ." Constant " DUP ID. CR
681 ." Primitive or word with unrecognized codeword." CR
685 ( begin the definition with : NAME [IMMEDIATE] )
686 ( [CHAR] : EMIT SPACE DUP ID. SPACE
687 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN CR 4 )
691 >PFA ( get the data address, ie. points after DOCOL | end-of-word start-of-data )
693 ( now we start decompiling until we hit the end of the word )
697 DUP @ ( end start codeword )
700 ['] LIT OF ( is it LIT ? )
701 1+ DUP @ ( get next word which is the integer constant )
704 ['] LITSTRING OF ( is it LITSTRING ? )
705 [CHAR] S EMIT [CHAR] " EMIT SPACE ( print S"<space> )
706 1+ DUP @ ( get the length word )
707 SWAP 1+ SWAP ( end start+1 length )
708 2DUP TYPE ( print the string )
709 [CHAR] " EMIT SPACE ( finish the string with a final quote )
710 + ( end start+1+len, aligned )
711 1- ( because we're about to add 4 below )
713 ['] 0BRANCH OF ( is it 0BRANCH ? )
715 1+ DUP @ ( print the offset )
719 ['] BRANCH OF ( is it BRANCH ? )
721 1+ DUP @ ( print the offset )
725 ['] ['] OF ( is it ['] ? )
727 1+ DUP @ ( get the next codeword )
728 CFA> ( and force it to be printed as a dictionary entry )
731 ['] EXIT OF ( is it EXIT? )
732 ( We expect the last word to be EXIT, and if it is then we don't print it
733 because EXIT is normally implied by ;. EXIT can also appear in the middle
734 of words, and then it needs to be printed. )
735 2DUP ( end start end start )
736 1+ ( end start end start+1 )
737 <> IF ( end start | we're not at the end )
742 DUP ( in the default case we always need to DUP before using )
743 CFA> ( look up the codeword to get the dictionary entry )
744 ID. SPACE ( and print it )
752 2DROP ( restore stack )
756 ( MEMORY ------------------------------------------------------------------ )
758 : UNUSED ( -- cells )