11 : CELLS ; \ Allow for slightly more portable code
13 : DEPTH PSP@ PSP0 @ - ;
18 : LITERAL IMMEDIATE ['] LIT , , ;
20 : ':' [ CHAR : ] LITERAL ;
21 : ';' [ CHAR ; ] LITERAL ;
22 : '(' [ CHAR ( ] LITERAL ;
23 : ')' [ CHAR ) ] LITERAL ;
24 : '<' [ CHAR < ] LITERAL ;
25 : '>' [ CHAR > ] LITERAL ;
26 : '"' [ CHAR " ] LITERAL ;
27 : 'A' [ CHAR A ] LITERAL ;
28 : '0' [ CHAR 0 ] LITERAL ;
29 : '-' [ CHAR - ] LITERAL ;
30 : '.' [ CHAR . ] LITERAL ;
36 WORD \ get the next word
37 FIND \ find it in the dictionary
38 >CFA \ get its codeword
43 LATEST @ \ LATEST points to the word being compiled at the moment
44 >CFA \ get the codeword
48 : DEBUGON TRUE DEBUG ! ;
49 : DEBUGOFF FALSE DEBUG ! ;
51 \ CONTROL STRUCTURES ----------------------------------------------------------------------
54 ['] 0BRANCH , \ compile 0BRANCH
55 HERE @ \ save location of the offset on the stack
56 0 , \ compile a dummy offset
61 HERE @ SWAP - \ calculate the offset from the address saved on the stack
62 SWAP ! \ store the offset in the back-filled location
66 ['] BRANCH , \ definite branch to just over the false-part
67 HERE @ \ save location of the offset on the stack
68 0 , \ compile a dummy offset
69 SWAP \ now back-fill the original (IF) offset
70 DUP \ same as for THEN word above
76 HERE @ \ save location on the stack
80 ['] 0BRANCH , \ compile 0BRANCH
81 HERE @ - \ calculate the offset from the address saved on the stack
82 , \ compile the offset here
86 ['] BRANCH , \ compile BRANCH
87 HERE @ - \ calculate the offset back
88 , \ compile the offset here
92 ['] 0BRANCH , \ compile 0BRANCH
93 HERE @ \ save location of the offset2 on the stack
94 0 , \ compile a dummy offset2
98 ['] BRANCH , \ compile BRANCH
99 SWAP \ get the original offset (from BEGIN)
100 HERE @ - , \ and compile it after BRANCH
102 HERE @ SWAP - \ calculate the offset2
103 SWAP ! \ and back-fill it in the original location
107 ['] NOT , \ compile NOT (to reverse the test)
108 [COMPILE] IF \ continue by calling the normal IF
112 ['] LIT , -1 , [COMPILE] IF
114 ['] LIT , HERE @ 0 , ['] >R ,
119 ['] 2DUP , ['] - , [COMPILE] IF
121 ['] LIT , HERE @ 0 , ['] >R ,
131 ['] R> , ['] RDROP , ['] RDROP ,
132 ['] LIT , HERE @ 7 + , ['] DUP , ['] -ROT , ['] - , ['] SWAP , ['] ! ,
143 ['] DUP , \ Store copy of increment
145 ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] + , ['] 2DUP , ['] - ,
146 ['] SWAP , ['] >R , ['] SWAP , ['] >R , ['] SWAP , ['] >R ,
148 \ Condition differently depending on sign of increment
149 ['] SWAP , ['] 0>= , [COMPILE] IF
155 \ Branch back to begining of loop kernel
156 ['] 0BRANCH , HERE @ - ,
159 ['] RDROP , ['] RDROP , ['] RDROP ,
161 \ Record address of loop end for any LEAVEs to use
165 ['] 2DROP , \ Clean up if loop was entirely skipped (?DO)
174 \ COMMENTS ----------------------------------------------------------------------
177 1 \ allowed nested parens by keeping track of depth
179 KEY \ read next character
180 DUP '(' = IF \ open paren?
181 DROP \ drop the open paren
184 ')' = IF \ close paren?
188 DUP 0= UNTIL \ continue until we reach matching close paren, depth 0
189 DROP \ drop the depth counter
192 ( Some more complicated stack examples, showing the stack notation. )
193 : NIP ( x y -- y ) SWAP DROP ;
194 : TUCK ( x y -- y x y ) DUP -ROT ;
195 : PICK ( x_u ... x_1 x_0 u -- x_u ... x_1 x_0 x_u )
196 1+ ( add one because of 'u' on the stack )
197 PSP@ SWAP - ( add to the stack pointer )
200 : ROLL ( x_u x_u-1... x_0 u -- x_u-1 ... x_0 x_u )
201 1+ DUP PICK SWAP ( x_u x_u-1 ... x_0 x_u u+1 )
202 PSP@ 1- SWAP - PSP@ 2- SWAP
209 ( With the looping constructs, we can now write SPACES, which writes n spaces to stdout. )
218 ( Standard words for manipulating BASE. )
219 : DECIMAL ( -- ) 10 BASE ! ;
220 : HEX ( -- ) 16 BASE ! ;
222 ( Compute absolute value. )
245 ( PRINTING NUMBERS ---------------------------------------------------------------------- )
247 ( This is the underlying recursive definition of U. )
249 BASE @ /MOD ( width rem quot )
250 ?DUP IF ( if quotient <> 0 then )
251 RECURSE ( print the quotient )
254 ( print the remainder )
256 '0' ( decimal digits 0..9 )
258 10 - ( hex and beyond digits A..Z )
265 ( This word returns the width (in characters) of an unsigned number in the current base )
266 : UWIDTH ( u -- width )
267 BASE @ / ( rem quot )
268 ?DUP IF ( if quotient <> 0 then )
269 RECURSE 1+ ( return 1+recursive call )
278 UWIDTH ( width u uwidth )
279 ROT ( u uwidth width )
280 SWAP - ( u width-uwidth )
281 ( At this point if the requested width is narrower, we'll have a negative number on the stack.
282 Otherwise the number on the stack is the number of spaces to print. But SPACES won't print
283 a negative number of spaces anyway, so it's now safe to call SPACES ... )
285 ( ... and then call the underlying implementation of U. )
293 1 ( save a flag to remember that it was negative | width n 1 )
302 SWAP ( flag width u )
303 DUP ( flag width u u )
304 UWIDTH ( flag width u uwidth )
305 ROT ( flag u uwidth width )
306 SWAP - ( flag u width-uwidth )
311 IF ( was it negative? print the - character )
321 '<' EMIT DEPTH U. '>' EMIT SPACE
334 ( ? fetches the integer at an address and prints it. )
335 : ? ( addr -- ) @ . ;
337 ( c a b WITHIN returns true if a <= c and c < b )
354 ( STRINGS ---------------------------------------------------------------------- )
356 ( Since the smallest unit of memory in our system is 64 bits and since strings
357 are stored as arrays of 64 bit integers, the character store/fetch words are
358 just aliases of the standard store/fetch words. )
362 ( Block copy, however, is important and novel: )
363 : CMOVE ( src dest length -- )
369 -ROT OVER - ( length src (dest-src) )
370 -ROT DUP ROT + SWAP ( (dest-src) (src+length) src )
373 I @ ( (dest-src) i@ )
374 OVER I + ( (dest-src) i@ (dest-src+i) )
381 ( C, appends a byte to the current compiled word. )
387 : S" IMMEDIATE ( -- addr len )
388 STATE @ IF ( compiling? )
389 ['] LITSTRING , ( compile LITSTRING )
390 HERE @ ( save the address of the length word on the stack )
391 0 , ( dummy length - we don't know what it is yet )
394 KEY ( get next character of the string )
397 C, ( copy character )
399 DROP ( drop the double quote character at the end )
400 DUP ( get the saved address of the length word )
401 HERE @ SWAP - ( calculate the length )
402 1- ( subtract 1 (because we measured from the start of the length word) )
403 SWAP ! ( and back-fill the length location )
404 ELSE ( immediate mode )
405 HERE @ ( get the start address of the temporary space )
411 OVER C! ( save next character )
412 1+ ( increment address )
414 DROP ( drop the final " character )
415 HERE @ - ( calculate the length )
416 HERE @ ( push the start address )
421 : ." IMMEDIATE ( -- )
422 STATE @ IF ( compiling? )
423 [COMPILE] S" ( read the string, and compile LITSTRING, etc. )
424 ['] TELL , ( compile the final TELL )
426 ( In immediate mode, just read characters and print them until we get
427 to the ending double quote. )
432 DROP ( drop the double quote character )
433 EXIT ( return from this function )
440 ( CONSTANTS AND VARIABLES ------------------------------------------------------ )
443 WORD ( get the name (the name follows CONSTANT) )
444 CREATE ( make the dictionary entry )
445 DOCOL , ( append DOCOL (the codeword field of this word) )
446 ['] LIT , ( append the codeword LIT )
447 , ( append the value on the top of the stack )
448 ['] EXIT , ( append the codeword EXIT )
451 : ALLOT ( n -- addr )
452 HERE @ SWAP ( here n )
453 HERE +! ( adds n to HERE, after this the old value of HERE is still on the stack )
457 1 CELLS ALLOT ( allocate 1 cell of memory, push the pointer to this memory )
458 WORD CREATE ( make the dictionary entry (the name follows VARIABLE) )
459 DOCOL , ( append DOCOL (the codeword field of this word) )
460 ['] LIT , ( append the codeword LIT )
461 , ( append the pointer to the new memory )
462 ['] EXIT , ( append the codeword EXIT )
467 WORD CREATE ( make the dictionary entry (the name follows VALUE) )
468 DOCOL , ( append DOCOL )
469 ['] LIT , ( append the codeword LIT )
470 , ( append the initial value )
471 ['] EXIT , ( append the codeword EXIT )
474 : TO IMMEDIATE ( n -- )
475 WORD ( get the name of the value )
476 FIND ( look it up in the dictionary )
477 >DFA ( get a pointer to the first data field (the 'LIT') )
478 1+ ( increment to point at the value )
479 STATE @ IF ( compiling? )
480 ['] LIT , ( compile LIT )
481 , ( compile the address of the value )
482 ['] ! , ( compile ! )
483 ELSE ( immediate mode )
484 ! ( update it straightaway )
488 ( x +TO VAL adds x to VAL )
490 WORD ( get the name of the value )
491 FIND ( look it up in the dictionary )
492 >DFA ( get a pointer to the first data field (the 'LIT') )
493 1+ ( increment to point at the value )
494 STATE @ IF ( compiling? )
495 ['] LIT , ( compile LIT )
496 , ( compile the address of the value )
497 ['] +! , ( compile +! )
498 ELSE ( immediate mode )
499 +! ( update it straightaway )
504 ( PRINTING THE DICTIONARY ------------------------------------------------------ )
507 1+ ( skip over the link pointer )
508 DUP @ ( get the flags/length byte )
509 F_LENMASK AND ( mask out the flags - just want the length )
512 DUP 0> ( length > 0? )
514 SWAP 1+ ( addr len -- len addr+1 )
515 DUP @ ( len addr -- len addr char | get the next character)
516 EMIT ( len addr char -- len addr | and print it)
517 SWAP 1- ( len addr -- addr len-1 | subtract one from length )
519 2DROP ( len addr -- )
523 1+ ( skip over the link pointer )
524 @ ( get the flags/length byte )
525 F_HIDDEN AND ( mask the F_HIDDEN flag and return it (as a truth value) )
528 1+ ( skip over the link pointer )
529 @ ( get the flags/length byte )
530 F_IMMED AND ( mask the F_IMMED flag and return it (as a truth value) )
534 LATEST @ ( start at LATEST dictionary entry )
536 ?DUP ( while link pointer is not null )
538 DUP ?HIDDEN NOT IF ( ignore hidden words )
539 DUP ID. ( but if not hidden, print the word )
542 @ ( dereference the link pointer - go to previous word )
547 ( FORGET ---------------------------------------------------------------------- )
550 WORD FIND ( find the word, gets the dictionary entry address )
551 DUP @ LATEST ! ( set LATEST to point to the previous word )
552 HERE ! ( and store HERE with the dictionary address )
555 ( DUMP ------------------------------------------------------------------------ )
559 ( CASE ------------------------------------------------------------------------ )
562 0 ( push 0 to mark the bottom of the stack )
566 ['] OVER , ( compile OVER )
567 ['] = , ( compile = )
568 [COMPILE] IF ( compile IF )
569 ['] DROP , ( compile DROP )
573 [COMPILE] ELSE ( ENDOF is the same as ELSE )
577 ['] DROP , ( compile DROP )
579 ( keep compiling THEN until we get to our zero marker )
588 ( DECOMPILER ------------------------------------------------------------------ )
591 LATEST @ ( start at LATEST dictionary entry )
593 ?DUP ( while link pointer is not null )
595 2DUP SWAP ( cfa curr curr cfa )
596 < IF ( current dictionary entry < cfa? )
597 NIP ( leave curr dictionary entry on the stack )
600 @ ( follow link pointer back )
602 DROP ( restore stack )
603 0 ( sorry, nothing found )
607 WORD FIND ( find the dictionary entry to decompile )
609 ( Now we search again, looking for the next word in the dictionary. This gives us
610 the length of the word that we will be decompiling. (Well, mostly it does). )
611 HERE @ ( address of the end of the last compiled word )
612 LATEST @ ( word last curr )
614 2 PICK ( word last curr word )
615 OVER ( word last curr word curr )
616 <> ( word last curr word<>curr? )
617 WHILE ( word last curr )
619 DUP @ ( word curr prev (which becomes: word last curr) )
622 DROP ( at this point, the stack is: start-of-word end-of-word )
623 SWAP ( end-of-word start-of-word )
625 ( begin the definition with : NAME [IMMEDIATE] )
626 ':' EMIT SPACE DUP ID. SPACE
627 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN
629 >DFA ( get the data address, ie. points after DOCOL | end-of-word start-of-data )
631 ( now we start decompiling until we hit the end of the word )
635 DUP @ ( end start codeword )
638 ['] LIT OF ( is it LIT ? )
639 1+ DUP @ ( get next word which is the integer constant )
642 ['] LITSTRING OF ( is it LITSTRING ? )
643 [ CHAR S ] LITERAL EMIT '"' EMIT SPACE ( print S"<space> )
644 1+ DUP @ ( get the length word )
645 SWAP 1+ SWAP ( end start+1 length )
646 2DUP TELL ( print the string )
647 '"' EMIT SPACE ( finish the string with a final quote )
648 + ( end start+1+len, aligned )
649 1- ( because we're about to add 4 below )
651 ['] 0BRANCH OF ( is it 0BRANCH ? )
653 1+ DUP @ ( print the offset )
657 ['] BRANCH OF ( is it BRANCH ? )
659 1+ DUP @ ( print the offset )
663 ['] ['] OF ( is it ['] ? )
664 [ CHAR ' ] LITERAL EMIT SPACE
665 1+ DUP @ ( get the next codeword )
666 CFA> ( and force it to be printed as a dictionary entry )
669 ['] EXIT OF ( is it EXIT? )
670 ( We expect the last word to be EXIT, and if it is then we don't print it
671 because EXIT is normally implied by ;. EXIT can also appear in the middle
672 of words, and then it needs to be printed. )
673 2DUP ( end start end start )
674 1+ ( end start end start+1 )
675 <> IF ( end start | we're not at the end )
680 DUP ( in the default case we always need to DUP before using )
681 CFA> ( look up the codeword to get the dictionary entry )
682 ID. SPACE ( and print it )
690 2DROP ( restore stack )
694 ( WELCOME MESSAGE ------------------------------------------------------------- )
696 CR CR ." --- TimForth initialized --- "