3 ; \ We can now comment!
5 \ BASIC DEFINITIONS ----------------------------------------------------------------------
17 \ Translate a number of cells into memory units
18 \ (in our case 1 cell = 1 memory unit)
21 \ Since the smallest unit of memory in our system is 64 bits and since strings
22 \ are stored as arrays of 64 bit integers, the character store/fetch words are
23 \ just aliases of the standard store/fetch words.
28 : DEPTH PSP@ PSP0 @ - ;
33 : LITERAL IMMEDIATE ['] LIT , , ;
35 : ' BL WORD FIND >CFA ;
47 BL WORD \ get the next word
48 FIND \ find it in the dictionary
49 >CFA \ get its codeword
54 LATEST @ \ LATEST points to the word being compiled at the moment
55 >CFA \ get the codeword
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 , ['] ! ,
154 ['] DUP , \ Store copy of increment
156 ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] + , ['] 2DUP , ['] - ,
157 ['] SWAP , ['] >R , ['] SWAP , ['] >R , ['] SWAP , ['] >R ,
161 \ Condition differently depending on sign of increment
162 ['] SWAP , ['] 0>= , [COMPILE] IF
170 \ Branch back to begining of loop kernel
171 ['] 0BRANCH , HERE @ - ,
174 ['] RDROP , ['] RDROP , ['] RDROP ,
178 \ Record address of loop end for any LEAVEs to use
182 ['] 2DROP , \ Clean up if loop was entirely skipped (?DO)
192 \ CASE ------------------------------------------------------------------------
195 0 \ push 0 to mark the bottom of the stack
199 ['] OVER , \ compile OVER
201 [COMPILE] IF \ compile IF
202 ['] DROP , \ compile DROP
206 [COMPILE] ELSE \ ENDOF is the same as ELSE
210 ['] DROP , \ compile DROP
212 \ keep compiling THEN until we get to our zero marker
221 \ COMMENTS ----------------------------------------------------------------------
224 1 \ allowed nested parens by keeping track of depth
226 >IN @ #TIB @ >= IF \ End of TIB?
227 QUERY \ Get next line
230 TIB >IN @ + @ 1 >IN +!
231 DUP [CHAR] ( = IF \ open paren?
232 DROP \ drop the open paren
235 [CHAR] ) = IF \ close paren?
239 DUP 0= UNTIL \ continue until we reach matching close paren, depth 0
240 DROP \ drop the depth counter
243 ( Some more complicated stack examples, showing the stack notation. )
244 : NIP ( x y -- y ) SWAP DROP ;
245 : TUCK ( x y -- y x y ) DUP -ROT ;
246 : PICK ( x_u ... x_1 x_0 u -- x_u ... x_1 x_0 x_u )
247 1+ ( add one because of 'u' on the stack )
248 PSP@ SWAP - ( add to the stack pointer )
251 : ROLL ( x_u x_u-1... x_0 u -- x_u-1 ... x_0 x_u )
252 1+ DUP PICK SWAP ( x_u x_u-1 ... x_0 x_u u+1 )
253 PSP@ 1- SWAP - PSP@ 2- SWAP
260 ( With the looping constructs, we can now write SPACES, which writes n spaces to stdout. )
269 ( Standard words for manipulating BASE. )
270 : DECIMAL ( -- ) 10 BASE ! ;
271 : HEX ( -- ) 16 BASE ! ;
273 ( Compute absolute value. )
296 ( PRINTING NUMBERS ---------------------------------------------------------------------- )
298 ( This is the underlying recursive definition of U. )
300 BASE @ /MOD ( width rem quot )
301 ?DUP IF ( if quotient <> 0 then )
302 RECURSE ( print the quotient )
305 ( print the remainder )
307 [CHAR] 0 ( decimal digits 0..9 )
309 10 - ( hex and beyond digits A..Z )
316 ( This word returns the width (in characters) of an unsigned number in the current base )
317 : UWIDTH ( u -- width )
318 BASE @ / ( rem quot )
319 ?DUP IF ( if quotient <> 0 then )
320 RECURSE 1+ ( return 1+recursive call )
329 UWIDTH ( width u uwidth )
330 ROT ( u uwidth width )
331 SWAP - ( u width-uwidth )
332 ( At this point if the requested width is narrower, we'll have a negative number on the stack.
333 Otherwise the number on the stack is the number of spaces to print. But SPACES won't print
334 a negative number of spaces anyway, so it's now safe to call SPACES ... )
336 ( ... and then call the underlying implementation of U. )
344 1 ( save a flag to remember that it was negative | width n 1 )
353 SWAP ( flag width u )
354 DUP ( flag width u u )
355 UWIDTH ( flag width u uwidth )
356 ROT ( flag u uwidth width )
357 SWAP - ( flag u width-uwidth )
362 IF ( was it negative? print the - character )
372 [CHAR] < EMIT DEPTH U. [CHAR] > EMIT SPACE
385 ( ? fetches the integer at an address and prints it. )
386 : ? ( addr -- ) @ . ;
388 ( c a b WITHIN returns true if a <= c and c < b )
405 ( STRINGS ---------------------------------------------------------------------- )
408 ( Block copy, however, is important and novel: )
409 : CMOVE ( src dest length -- )
415 -ROT OVER - ( length src (dest-src) )
416 -ROT DUP ROT + SWAP ( (dest-src) (src+length) src )
419 I @ ( (dest-src) i@ )
420 OVER I + ( (dest-src) i@ (dest-src+i) )
427 ( C, appends a byte to the current compiled word. )
433 : S" IMMEDIATE ( -- addr len )
434 STATE @ IF ( compiling? )
435 ['] LITSTRING , ( compile LITSTRING )
436 HERE @ ( save the address of the length word on the stack )
437 0 , ( dummy length - we don't know what it is yet )
440 KEY ( get next character of the string )
443 C, ( copy character )
445 DROP ( drop the double quote character at the end )
446 DUP ( get the saved address of the length word )
447 HERE @ SWAP - ( calculate the length )
448 1- ( subtract 1 (because we measured from the start of the length word) )
449 SWAP ! ( and back-fill the length location )
450 ELSE ( immediate mode )
451 HERE @ ( get the start address of the temporary space )
457 OVER C! ( save next character )
458 1+ ( increment address )
460 DROP ( drop the final " character )
461 HERE @ - ( calculate the length )
462 HERE @ ( push the start address )
467 : ." IMMEDIATE ( -- )
468 [COMPILE] S" ( read the string, and compile LITSTRING, etc. )
469 ['] TYPE , ( compile the final TYPE )
477 DROP ( drop the double quote character )
478 EXIT ( return from this function )
484 ( Converts address of counted string into address of
485 start of string and length of string. )
486 : COUNT ( addr1 -- addr2 n )
490 ( CONSTANTS AND VARIABLES ------------------------------------------------------ )
493 BL WORD HEADER ( make dictionary entry (the name follows CONSTANT) )
494 DOCOL , ( append DOCOL (the codeword field of this word) )
495 ['] LIT , ( append the codeword LIT )
496 , ( append the value on the top of the stack )
497 ['] EXIT , ( append the codeword EXIT )
501 HERE +! ( adds n to HERE, after this the old value of HERE is still on the stack )
506 1 CELLS ALLOT ( allocate 1 cell of memory, push the pointer to this memory )
511 BL WORD HEADER ( make the dictionary entry (the name follows VALUE) )
512 DOCOL , ( append DOCOL )
513 ['] LIT , ( append the codeword LIT )
514 , ( append the initial value )
515 ['] EXIT , ( append the codeword EXIT )
518 : TO IMMEDIATE ( n -- )
519 BL WORD ( get the name of the value )
520 FIND ( look it up in the dictionary )
521 >PFA ( get a pointer to the first data field (the 'LIT') )
522 1+ ( increment to point at the value )
523 STATE @ IF ( compiling? )
524 ['] LIT , ( compile LIT )
525 , ( compile the address of the value )
526 ['] ! , ( compile ! )
527 ELSE ( immediate mode )
528 ! ( update it straightaway )
532 ( x +TO VAL adds x to VAL )
534 BL WORD ( get the name of the value )
535 FIND ( look it up in the dictionary )
536 >PFA ( get a pointer to the first data field (the 'LIT') )
537 1+ ( increment to point at the value )
538 STATE @ IF ( compiling? )
539 ['] LIT , ( compile LIT )
540 , ( compile the address of the value )
541 ['] +! , ( compile +! )
542 ELSE ( immediate mode )
543 +! ( update it straightaway )
547 ( Fill u ints, starting at a, with the value b )
559 ( PRINTING THE DICTIONARY ------------------------------------------------------ )
562 1+ ( skip over the link pointer )
563 DUP @ ( get the flags/length byte )
564 F_LENMASK AND ( mask out the flags - just want the length )
567 DUP 0> ( length > 0? )
569 SWAP 1+ ( addr len -- len addr+1 )
570 DUP @ ( len addr -- len addr char | get the next character)
571 DUP 32 >= OVER 127 <= AND IF
572 EMIT ( len addr char -- len addr | and print it)
578 SWAP 1- ( len addr -- addr len-1 | subtract one from length )
580 2DROP ( len addr -- )
584 1+ ( skip over the link pointer )
585 @ ( get the flags/length byte )
586 F_HIDDEN AND ( mask the F_HIDDEN flag and return it (as a truth value) )
589 1+ ( skip over the link pointer )
590 @ ( get the flags/length byte )
591 F_IMMED AND ( mask the F_IMMED flag and return it (as a truth value) )
595 LATEST @ ( start at LATEST dictionary entry )
597 ?DUP ( while link pointer is not null )
599 DUP ?HIDDEN NOT IF ( ignore hidden words )
600 DUP ID. ( but if not hidden, print the word )
603 @ ( dereference the link pointer - go to previous word )
609 ( FORGET ---------------------------------------------------------------------- )
612 BL WORD FIND ( find the word, gets the dictionary entry address )
613 DUP @ LATEST ! ( set LATEST to point to the previous word )
614 HERE ! ( and store HERE with the dictionary address )
617 ( DUMP ------------------------------------------------------------------------ )
622 ( DECOMPILER ------------------------------------------------------------------ )
625 LATEST @ ( start at LATEST dictionary entry )
627 ?DUP ( while link pointer is not null )
629 2DUP SWAP ( cfa curr curr cfa )
630 < IF ( current dictionary entry < cfa? )
631 NIP ( leave curr dictionary entry on the stack )
634 @ ( follow link pointer back )
636 DROP ( restore stack )
637 0 ( sorry, nothing found )
641 BL WORD 2DUP FIND ( find the dictionary entry to decompile )
644 ." Word '" TYPE ." ' not found in dictionary."
650 ( Now we search again, looking for the next word in the dictionary. This gives us
651 the length of the word that we will be decompiling. (Well, mostly it does). )
652 HERE @ ( address of the end of the last compiled word )
653 LATEST @ ( word last curr )
655 2 PICK ( word last curr word )
656 OVER ( word last curr word curr )
657 <> ( word last curr word<>curr? )
658 WHILE ( word last curr )
660 DUP @ ( word curr prev (which becomes: word last curr) )
663 DROP ( at this point, the stack is: start-of-word end-of-word )
664 SWAP ( end-of-word start-of-word )
669 [CHAR] : EMIT SPACE DUP ID. SPACE
670 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN CR
673 \ Variable definition
674 ." Variable " DUP ID. CR
678 \ Constant definition
679 ." Constant " DUP ID. CR
684 ." Primitive or word with unrecognized codeword." CR
688 ( begin the definition with : NAME [IMMEDIATE] )
689 ( [CHAR] : EMIT SPACE DUP ID. SPACE
690 DUP ?IMMEDIATE IF ." IMMEDIATE " THEN CR 4 )
694 >PFA ( get the data address, ie. points after DOCOL | end-of-word start-of-data )
696 ( now we start decompiling until we hit the end of the word )
700 DUP @ ( end start codeword )
703 ['] LIT OF ( is it LIT ? )
704 1+ DUP @ ( get next word which is the integer constant )
707 ['] LITSTRING OF ( is it LITSTRING ? )
708 [CHAR] S EMIT [CHAR] " EMIT SPACE ( print S"<space> )
709 1+ DUP @ ( get the length word )
710 SWAP 1+ SWAP ( end start+1 length )
711 2DUP TYPE ( print the string )
712 [CHAR] " EMIT SPACE ( finish the string with a final quote )
713 + ( end start+1+len, aligned )
714 1- ( because we're about to add 4 below )
716 ['] 0BRANCH OF ( is it 0BRANCH ? )
718 1+ DUP @ ( print the offset )
722 ['] BRANCH OF ( is it BRANCH ? )
724 1+ DUP @ ( print the offset )
728 ['] ['] OF ( is it ['] ? )
730 1+ DUP @ ( get the next codeword )
731 CFA> ( and force it to be printed as a dictionary entry )
734 ['] EXIT OF ( is it EXIT? )
735 ( We expect the last word to be EXIT, and if it is then we don't print it
736 because EXIT is normally implied by ;. EXIT can also appear in the middle
737 of words, and then it needs to be printed. )
738 2DUP ( end start end start )
739 1+ ( end start end start+1 )
740 <> IF ( end start | we're not at the end )
745 DUP ( in the default case we always need to DUP before using )
746 CFA> ( look up the codeword to get the dictionary entry )
747 ID. SPACE ( and print it )
755 2DROP ( restore stack )
759 ( MEMORY ------------------------------------------------------------------ )
761 : UNUSED ( -- cells )