17 : CELLS ; \ Allow for slightly more portable code
19 : DEPTH PSP@ PSP0 @ - ;
21 : LITERAL IMMEDIATE ' LIT , , ;
23 : ':' [ CHAR : ] LITERAL ;
24 : ';' [ CHAR ; ] LITERAL ;
25 : '(' [ CHAR ( ] LITERAL ;
26 : ')' [ CHAR ) ] LITERAL ;
27 : '<' [ CHAR < ] LITERAL ;
28 : '>' [ CHAR > ] LITERAL ;
29 : '"' [ CHAR " ] LITERAL ;
30 : 'A' [ CHAR A ] LITERAL ;
31 : '0' [ CHAR 0 ] LITERAL ;
32 : '-' [ CHAR - ] LITERAL ;
33 : '.' [ 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 \ CONTROL STRUCTURES ----------------------------------------------------------------------
51 ' 0BRANCH , \ compile 0BRANCH
52 HERE @ \ save location of the offset on the stack
53 0 , \ compile a dummy offset
58 HERE @ SWAP - \ calculate the offset from the address saved on the stack
59 SWAP ! \ store the offset in the back-filled location
63 ' BRANCH , \ definite branch to just over the false-part
64 HERE @ \ save location of the offset on the stack
65 0 , \ compile a dummy offset
66 SWAP \ now back-fill the original (IF) offset
67 DUP \ same as for THEN word above
73 HERE @ \ save location on the stack
77 ' 0BRANCH , \ compile 0BRANCH
78 HERE @ - \ calculate the offset from the address saved on the stack
79 , \ compile the offset here
83 ' BRANCH , \ compile BRANCH
84 HERE @ - \ calculate the offset back
85 , \ compile the offset here
89 ' 0BRANCH , \ compile 0BRANCH
90 HERE @ \ save location of the offset2 on the stack
91 0 , \ compile a dummy offset2
95 ' BRANCH , \ compile BRANCH
96 SWAP \ get the original offset (from BEGIN)
97 HERE @ - , \ and compile it after BRANCH
99 HERE @ SWAP - \ calculate the offset2
100 SWAP ! \ and back-fill it in the original location
104 ' NOT , \ compile NOT (to reverse the test)
105 [COMPILE] IF \ continue by calling the normal IF
116 ' R> , ' R> , ' -ROT , ' + , ' 2DUP , ' - ,
117 ' SWAP , ' >R , ' SWAP , ' >R ,
129 \ COMMENTS ----------------------------------------------------------------------
132 1 \ allowed nested parens by keeping track of depth
134 KEY \ read next character
135 DUP '(' = IF \ open paren?
136 DROP \ drop the open paren
139 ')' = IF \ close paren?
143 DUP 0= UNTIL \ continue until we reach matching close paren, depth 0
144 DROP \ drop the depth counter
147 ( Some more complicated stack examples, showing the stack notation. )
148 : NIP ( x y -- y ) SWAP DROP ;
149 : TUCK ( x y -- y x y ) DUP ROT ;
150 : PICK ( x_u ... x_1 x_0 u -- x_u ... x_1 x_0 x_u )
151 1+ ( add one because of 'u' on the stack )
152 PSP@ SWAP - ( add to the stack pointer )
157 ( With the looping constructs, we can now write SPACES, which writes n spaces to stdout. )
160 DUP 0> ( while n > 0 )
162 SPACE ( print a space )
163 1- ( until we count down to 0 )
168 ( Standard words for manipulating BASE. )
169 : DECIMAL ( -- ) 10 BASE ! ;
170 : HEX ( -- ) 16 BASE ! ;
172 ( Compute absolute value. )
179 ( PRINTING NUMBERS ---------------------------------------------------------------------- )
181 ( This is the underlying recursive definition of U. )
183 BASE @ /MOD ( width rem quot )
184 ?DUP IF ( if quotient <> 0 then )
185 RECURSE ( print the quotient )
188 ( print the remainder )
190 '0' ( decimal digits 0..9 )
192 10 - ( hex and beyond digits A..Z )
199 ( This word returns the width (in characters) of an unsigned number in the current base )
200 : UWIDTH ( u -- width )
201 BASE @ / ( rem quot )
202 ?DUP IF ( if quotient <> 0 then )
203 RECURSE 1+ ( return 1+recursive call )
212 UWIDTH ( width u uwidth )
213 -ROT ( u uwidth width )
214 SWAP - ( u width-uwidth )
215 ( At this point if the requested width is narrower, we'll have a negative number on the stack.
216 Otherwise the number on the stack is the number of spaces to print. But SPACES won't print
217 a negative number of spaces anyway, so it's now safe to call SPACES ... )
219 ( ... and then call the underlying implementation of U. )
227 1 ( save a flag to remember that it was negative | width n 1 )
236 SWAP ( flag width u )
237 DUP ( flag width u u )
238 UWIDTH ( flag width u uwidth )
239 -ROT ( flag u uwidth width )
240 SWAP - ( flag u width-uwidth )
245 IF ( was it negative? print the - character )
255 '<' EMIT DEPTH U. '>' EMIT SPACE
268 ( ? fetches the integer at an address and prints it. )
269 : ? ( addr -- ) @ . ;
271 ( c a b WITHIN returns true if a <= c and c < b )