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 )