: / /MOD SWAP DROP ; : MOD /MOD DROP ; : */ -ROT * SWAP / ; : NEGATE 0 SWAP - ; : TRUE -1 ; : FALSE 0 ; : NOT 0= ; : CELLS ; \ Allow for slightly more portable code : DEPTH PSP@ PSP0 @ - ; : '\n' 10 ; : BL 32 ; : LITERAL IMMEDIATE ['] LIT , , ; : ':' [ CHAR : ] LITERAL ; : ';' [ CHAR ; ] LITERAL ; : '(' [ CHAR ( ] LITERAL ; : ')' [ CHAR ) ] LITERAL ; : '<' [ CHAR < ] LITERAL ; : '>' [ CHAR > ] LITERAL ; : '"' [ CHAR " ] LITERAL ; : 'A' [ CHAR A ] LITERAL ; : '0' [ CHAR 0 ] LITERAL ; : '-' [ CHAR - ] LITERAL ; : '.' [ CHAR . ] LITERAL ; : CR '\n' emit ; : SPACE BL emit ; : [COMPILE] IMMEDIATE WORD \ get the next word FIND \ find it in the dictionary >CFA \ get its codeword , \ and compile that ; : RECURSE IMMEDIATE LATEST @ \ LATEST points to the word being compiled at the moment >CFA \ get the codeword , \ compile it ; : DEBUGON TRUE DEBUG ! ; : DEBUGOFF FALSE DEBUG ! ; \ CONTROL STRUCTURES ---------------------------------------------------------------------- : IF IMMEDIATE ['] 0BRANCH , \ compile 0BRANCH HERE @ \ save location of the offset on the stack 0 , \ compile a dummy offset ; : THEN IMMEDIATE DUP HERE @ SWAP - \ calculate the offset from the address saved on the stack SWAP ! \ store the offset in the back-filled location ; : ELSE IMMEDIATE ['] BRANCH , \ definite branch to just over the false-part HERE @ \ save location of the offset on the stack 0 , \ compile a dummy offset SWAP \ now back-fill the original (IF) offset DUP \ same as for THEN word above HERE @ SWAP - SWAP ! ; : BEGIN IMMEDIATE HERE @ \ save location on the stack ; : UNTIL IMMEDIATE ['] 0BRANCH , \ compile 0BRANCH HERE @ - \ calculate the offset from the address saved on the stack , \ compile the offset here ; : AGAIN IMMEDIATE ['] BRANCH , \ compile BRANCH HERE @ - \ calculate the offset back , \ compile the offset here ; : WHILE IMMEDIATE ['] 0BRANCH , \ compile 0BRANCH HERE @ \ save location of the offset2 on the stack 0 , \ compile a dummy offset2 ; : REPEAT IMMEDIATE ['] BRANCH , \ compile BRANCH SWAP \ get the original offset (from BEGIN) HERE @ - , \ and compile it after BRANCH DUP HERE @ SWAP - \ calculate the offset2 SWAP ! \ and back-fill it in the original location ; : UNLESS IMMEDIATE ['] NOT , \ compile NOT (to reverse the test) [COMPILE] IF \ continue by calling the normal IF ; : DO IMMEDIATE ['] LIT , -1 , [COMPILE] IF ['] >R , ['] >R , ['] LIT , HERE @ 0 , ['] >R , HERE @ ; : ?DO IMMEDIATE ['] 2DUP , ['] - , [COMPILE] IF ['] >R , ['] >R , ['] LIT , HERE @ 0 , ['] >R , HERE @ ; : I RSP@ 3 - @ ; : J RSP@ 6 - @ ; : ?LEAVE IMMEDIATE ['] 0BRANCH , 13 , ['] R> , ['] RDROP , ['] RDROP , ['] LIT , HERE @ 7 + , ['] DUP , ['] -ROT , ['] - , ['] SWAP , ['] ! , ['] BRANCH , 0 , ; : LEAVE IMMEDIATE ['] LIT , -1 , [COMPILE] ?LEAVE ; : +LOOP IMMEDIATE ['] DUP , \ Store copy of increment ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] R> , ['] SWAP , ['] + , ['] 2DUP , ['] - , ['] SWAP , ['] >R , ['] SWAP , ['] >R , ['] SWAP , ['] >R , \ Condition differently depending on sign of increment ['] SWAP , ['] 0>= , [COMPILE] IF ['] 0<= , [COMPILE] ELSE ['] 0> , [COMPILE] THEN \ Branch back to begining of loop kernel ['] 0BRANCH , HERE @ - , \ Clean up ['] RDROP , ['] RDROP , ['] RDROP , \ Record address of loop end for any LEAVEs to use HERE @ SWAP ! [COMPILE] ELSE ['] 2DROP , \ Clean up if loop was entirely skipped (?DO) [COMPILE] THEN ; : LOOP IMMEDIATE ['] LIT , 1 , [COMPILE] +LOOP ; \ COMMENTS ---------------------------------------------------------------------- : ( IMMEDIATE 1 \ allowed nested parens by keeping track of depth BEGIN KEY \ read next character DUP '(' = IF \ open paren? DROP \ drop the open paren 1+ \ depth increases ELSE ')' = IF \ close paren? 1- \ depth decreases THEN THEN DUP 0= UNTIL \ continue until we reach matching close paren, depth 0 DROP \ drop the depth counter ; ( Some more complicated stack examples, showing the stack notation. ) : NIP ( x y -- y ) SWAP DROP ; : TUCK ( x y -- y x y ) DUP -ROT ; : PICK ( x_u ... x_1 x_0 u -- x_u ... x_1 x_0 x_u ) 1+ ( add one because of 'u' on the stack ) PSP@ SWAP - ( add to the stack pointer ) @ ( and fetch ) ; : ROLL ( x_u x_u-1... x_0 u -- x_u-1 ... x_0 x_u ) 1+ DUP PICK SWAP ( x_u x_u-1 ... x_0 x_u u+1 ) PSP@ 1- SWAP - PSP@ 2- SWAP DO i 1+ @ i ! LOOP SWAP DROP ; ( With the looping constructs, we can now write SPACES, which writes n spaces to stdout. ) : SPACES ( n -- ) DUP 0> IF 0 DO SPACE LOOP ELSE DROP THEN ; ( Standard words for manipulating BASE. ) : DECIMAL ( -- ) 10 BASE ! ; : HEX ( -- ) 16 BASE ! ; ( Compute absolute value. ) : ABS ( n -- |n| ) dup 0< if negate then ; : MAX ( n m -- max ) 2dup - 0< if swap drop else drop then ; : MIN ( n m -- max ) 2dup - 0> if swap drop else drop then ; ( PRINTING NUMBERS ---------------------------------------------------------------------- ) ( This is the underlying recursive definition of U. ) : U. ( u -- ) BASE @ /MOD ( width rem quot ) ?DUP IF ( if quotient <> 0 then ) RECURSE ( print the quotient ) THEN ( print the remainder ) DUP 10 < IF '0' ( decimal digits 0..9 ) ELSE 10 - ( hex and beyond digits A..Z ) 'A' THEN + EMIT ; ( This word returns the width (in characters) of an unsigned number in the current base ) : UWIDTH ( u -- width ) BASE @ / ( rem quot ) ?DUP IF ( if quotient <> 0 then ) RECURSE 1+ ( return 1+recursive call ) ELSE 1 ( return 1 ) THEN ; : U.R ( u width -- ) SWAP ( width u ) DUP ( width u u ) UWIDTH ( width u uwidth ) ROT ( u uwidth width ) SWAP - ( u width-uwidth ) ( At this point if the requested width is narrower, we'll have a negative number on the stack. Otherwise the number on the stack is the number of spaces to print. But SPACES won't print a negative number of spaces anyway, so it's now safe to call SPACES ... ) SPACES ( ... and then call the underlying implementation of U. ) U. ; : .R ( n width -- ) SWAP ( width n ) DUP 0< IF NEGATE ( width u ) 1 ( save a flag to remember that it was negative | width n 1 ) -ROT ( 1 width u ) SWAP ( 1 u width ) 1- ( 1 u width-1 ) ELSE 0 ( width u 0 ) -ROT ( 0 width u ) SWAP ( 0 u width ) THEN SWAP ( flag width u ) DUP ( flag width u u ) UWIDTH ( flag width u uwidth ) ROT ( flag u uwidth width ) SWAP - ( flag u width-uwidth ) SPACES ( flag u ) SWAP ( u flag ) IF ( was it negative? print the - character ) '-' EMIT THEN U. ; : . 0 .R SPACE ; : .S ( -- ) '<' EMIT DEPTH U. '>' EMIT SPACE PSP0 @ 1+ BEGIN DUP PSP@ 2 - <= WHILE DUP @ . 1+ REPEAT DROP ; : U. U. SPACE ; ( ? fetches the integer at an address and prints it. ) : ? ( addr -- ) @ . ; ( c a b WITHIN returns true if a <= c and c < b ) : WITHIN -ROT ( b c a ) OVER ( b c a c ) <= IF > IF ( b c -- ) TRUE ELSE FALSE THEN ELSE 2DROP ( b c -- ) FALSE THEN ; ( STRINGS ---------------------------------------------------------------------- ) ( Since the smallest unit of memory in our system is 64 bits and since strings are stored as arrays of 64 bit integers, the character store/fetch words are just aliases of the standard store/fetch words. ) : C! ! ; : C@ @ ; ( Block copy, however, is important and novel: ) : CMOVE ( src dest length -- ) DUP 0<= IF EXIT THEN -ROT OVER - ( length src (dest-src) ) -ROT DUP ROT + SWAP ( (dest-src) (src+length) src ) DO I @ ( (dest-src) i@ ) OVER I + ( (dest-src) i@ (dest-src+i) ) ! ( (dest-src) ) LOOP DROP ; ( C, appends a byte to the current compiled word. ) : C, HERE @ C! 1 HERE +! ; : S" IMMEDIATE ( -- addr len ) STATE @ IF ( compiling? ) ['] LITSTRING , ( compile LITSTRING ) HERE @ ( save the address of the length word on the stack ) 0 , ( dummy length - we don't know what it is yet ) KEY DROP BEGIN KEY ( get next character of the string ) DUP '"' <> WHILE C, ( copy character ) REPEAT DROP ( drop the double quote character at the end ) DUP ( get the saved address of the length word ) HERE @ SWAP - ( calculate the length ) 1- ( subtract 1 (because we measured from the start of the length word) ) SWAP ! ( and back-fill the length location ) ELSE ( immediate mode ) HERE @ ( get the start address of the temporary space ) KEY DROP BEGIN KEY DUP '"' <> WHILE OVER C! ( save next character ) 1+ ( increment address ) REPEAT DROP ( drop the final " character ) HERE @ - ( calculate the length ) HERE @ ( push the start address ) SWAP ( addr len ) THEN ; : ." IMMEDIATE ( -- ) STATE @ IF ( compiling? ) [COMPILE] S" ( read the string, and compile LITSTRING, etc. ) ['] TELL , ( compile the final TELL ) ELSE ( In immediate mode, just read characters and print them until we get to the ending double quote. ) KEY DROP BEGIN KEY DUP '"' = IF DROP ( drop the double quote character ) EXIT ( return from this function ) THEN EMIT AGAIN THEN ; ( CONSTANTS AND VARIABLES ------------------------------------------------------ ) : CONSTANT WORD ( get the name (the name follows CONSTANT) ) CREATE ( make the dictionary entry ) DOCOL , ( append DOCOL (the codeword field of this word) ) ['] LIT , ( append the codeword LIT ) , ( append the value on the top of the stack ) ['] EXIT , ( append the codeword EXIT ) ; : ALLOT ( n -- addr ) HERE @ SWAP ( here n ) HERE +! ( adds n to HERE, after this the old value of HERE is still on the stack ) ; : VARIABLE 1 CELLS ALLOT ( allocate 1 cell of memory, push the pointer to this memory ) WORD CREATE ( make the dictionary entry (the name follows VARIABLE) ) DOCOL , ( append DOCOL (the codeword field of this word) ) ['] LIT , ( append the codeword LIT ) , ( append the pointer to the new memory ) ['] EXIT , ( append the codeword EXIT ) ; : VALUE ( n -- ) WORD CREATE ( make the dictionary entry (the name follows VALUE) ) DOCOL , ( append DOCOL ) ['] LIT , ( append the codeword LIT ) , ( append the initial value ) ['] EXIT , ( append the codeword EXIT ) ; : TO IMMEDIATE ( n -- ) WORD ( get the name of the value ) FIND ( look it up in the dictionary ) >DFA ( get a pointer to the first data field (the 'LIT') ) 1+ ( increment to point at the value ) STATE @ IF ( compiling? ) ['] LIT , ( compile LIT ) , ( compile the address of the value ) ['] ! , ( compile ! ) ELSE ( immediate mode ) ! ( update it straightaway ) THEN ; ( x +TO VAL adds x to VAL ) : +TO IMMEDIATE WORD ( get the name of the value ) FIND ( look it up in the dictionary ) >DFA ( get a pointer to the first data field (the 'LIT') ) 1+ ( increment to point at the value ) STATE @ IF ( compiling? ) ['] LIT , ( compile LIT ) , ( compile the address of the value ) ['] +! , ( compile +! ) ELSE ( immediate mode ) +! ( update it straightaway ) THEN ; ( PRINTING THE DICTIONARY ------------------------------------------------------ ) : ID. 1+ ( skip over the link pointer ) DUP @ ( get the flags/length byte ) F_LENMASK AND ( mask out the flags - just want the length ) BEGIN DUP 0> ( length > 0? ) WHILE SWAP 1+ ( addr len -- len addr+1 ) DUP @ ( len addr -- len addr char | get the next character) EMIT ( len addr char -- len addr | and print it) SWAP 1- ( len addr -- addr len-1 | subtract one from length ) REPEAT 2DROP ( len addr -- ) ; : ?HIDDEN 1+ ( skip over the link pointer ) @ ( get the flags/length byte ) F_HIDDEN AND ( mask the F_HIDDEN flag and return it (as a truth value) ) ; : ?IMMEDIATE 1+ ( skip over the link pointer ) @ ( get the flags/length byte ) F_IMMED AND ( mask the F_IMMED flag and return it (as a truth value) ) ; : WORDS LATEST @ ( start at LATEST dictionary entry ) BEGIN ?DUP ( while link pointer is not null ) WHILE DUP ?HIDDEN NOT IF ( ignore hidden words ) DUP ID. ( but if not hidden, print the word ) SPACE THEN @ ( dereference the link pointer - go to previous word ) REPEAT CR ; ( FORGET ---------------------------------------------------------------------- ) : FORGET WORD FIND ( find the word, gets the dictionary entry address ) DUP @ LATEST ! ( set LATEST to point to the previous word ) HERE ! ( and store HERE with the dictionary address ) ; ( DUMP ------------------------------------------------------------------------ ) \ TODO! ( CASE ------------------------------------------------------------------------ ) : CASE IMMEDIATE 0 ( push 0 to mark the bottom of the stack ) ; : OF IMMEDIATE ['] OVER , ( compile OVER ) ['] = , ( compile = ) [COMPILE] IF ( compile IF ) ['] DROP , ( compile DROP ) ; : ENDOF IMMEDIATE [COMPILE] ELSE ( ENDOF is the same as ELSE ) ; : ENDCASE IMMEDIATE ['] DROP , ( compile DROP ) ( keep compiling THEN until we get to our zero marker ) BEGIN ?DUP WHILE [COMPILE] THEN REPEAT ; ( DECOMPILER ------------------------------------------------------------------ ) : CFA> LATEST @ ( start at LATEST dictionary entry ) BEGIN ?DUP ( while link pointer is not null ) WHILE 2DUP SWAP ( cfa curr curr cfa ) < IF ( current dictionary entry < cfa? ) NIP ( leave curr dictionary entry on the stack ) EXIT THEN @ ( follow link pointer back ) REPEAT DROP ( restore stack ) 0 ( sorry, nothing found ) ; : SEE WORD FIND ( find the dictionary entry to decompile ) ( Now we search again, looking for the next word in the dictionary. This gives us the length of the word that we will be decompiling. (Well, mostly it does). ) HERE @ ( address of the end of the last compiled word ) LATEST @ ( word last curr ) BEGIN 2 PICK ( word last curr word ) OVER ( word last curr word curr ) <> ( word last curr word<>curr? ) WHILE ( word last curr ) NIP ( word curr ) DUP @ ( word curr prev (which becomes: word last curr) ) REPEAT DROP ( at this point, the stack is: start-of-word end-of-word ) SWAP ( end-of-word start-of-word ) ( begin the definition with : NAME [IMMEDIATE] ) ':' EMIT SPACE DUP ID. SPACE DUP ?IMMEDIATE IF ." IMMEDIATE " THEN >DFA ( get the data address, ie. points after DOCOL | end-of-word start-of-data ) ( now we start decompiling until we hit the end of the word ) BEGIN ( end start ) 2DUP > WHILE DUP @ ( end start codeword ) CASE ['] LIT OF ( is it LIT ? ) 1+ DUP @ ( get next word which is the integer constant ) . ( and print it ) ENDOF ['] LITSTRING OF ( is it LITSTRING ? ) [ CHAR S ] LITERAL EMIT '"' EMIT SPACE ( print S" ) 1+ DUP @ ( get the length word ) SWAP 1+ SWAP ( end start+1 length ) 2DUP TELL ( print the string ) '"' EMIT SPACE ( finish the string with a final quote ) + ( end start+1+len, aligned ) 1- ( because we're about to add 4 below ) ENDOF ['] 0BRANCH OF ( is it 0BRANCH ? ) ." 0BRANCH ( " 1+ DUP @ ( print the offset ) . ." ) " ENDOF ['] BRANCH OF ( is it BRANCH ? ) ." BRANCH ( " 1+ DUP @ ( print the offset ) . ." ) " ENDOF ['] ['] OF ( is it ['] ? ) [ CHAR ' ] LITERAL EMIT SPACE 1+ DUP @ ( get the next codeword ) CFA> ( and force it to be printed as a dictionary entry ) ID. SPACE ENDOF ['] EXIT OF ( is it EXIT? ) ( We expect the last word to be EXIT, and if it is then we don't print it because EXIT is normally implied by ;. EXIT can also appear in the middle of words, and then it needs to be printed. ) 2DUP ( end start end start ) 1+ ( end start end start+1 ) <> IF ( end start | we're not at the end ) ." EXIT " THEN ENDOF ( default case: ) DUP ( in the default case we always need to DUP before using ) CFA> ( look up the codeword to get the dictionary entry ) ID. SPACE ( and print it ) ENDCASE 1+ ( end start+1 ) REPEAT ';' EMIT CR 2DROP ( restore stack ) ; ( WELCOME MESSAGE ------------------------------------------------------------- ) CR CR ." --- TimForth initialized --- "