100 REM BRAINF*CK FOR TRS-80 LEVEL II BASIC
103 DB=0:REM SET TO 1 FOR DEBUGGING
105 REM FIRST MAKE SURE WE HAVE ENOUGH STRING HEAP FOR PROGRAM
110 READ C$:C=LEN(C$):IF C>M THEN M=C
120 PS=PS+C
130 IF C THEN 110
135 REM ALLOCATE THE HEAP
140 CLEAR 2*(PS+M)
145 REM RE-READ PROGRAM, REMEMBERING IT THIS TIME
150 RESTORE
160 P$=""
170 READ C$
180 P$=P$+C$
190 IF LEN(C$)<>0 THEN 170
195 REM PAIR UP BRACKETS INTO B%
200 DIM B%(LEN(P$))
205 REM TRACK OPEN BRACKETS IN O%
210 DIM O%(INT(LEN(P$)/2)):O=0
220 FOR I=1 TO LEN(P$)
230 : I$=MID$(P$,I,1)
240 : IF I$="(" OR I$="[" THEN O%(O)=I:O=O+1
250 : IF I$<>")" AND I$<>"]" THEN 290
260 : IF O=0 THEN PRINT "UNMATCHED BRACKET AT"I". ABORTING.":END
270 : O=O-1:M=O%(O)
280 : B%(I)=M:B%(M)=I
290 NEXT I
300 IF O THEN PRINT "UNMATCHED BRACKETS AT EOF. ABORTING.":END
303 REM SET MS TO NUMBER OF MEMORY CELLS NEEDED
305 REM THE BF SPEC REQUIRES 30000, WHICH DOES WORK ON A SYSTEM WITH 48K RAM.
307 REM THE DEMO HELLO-WORLD PROGRAM ONLY REQUIRES 4 CELLS.
310 MS=4:DIM M%(MS/2-1):MP=0
313 REM FUNCTION TO READ BYTE AT CELL N
315 DEF FNMP(N)=INT(M%(INT(N/2)) / (1+255*(N AND 1))) AND 255
320 FOR I=1 TO LEN(P$)
323 : IF MP<0 OR MP>=MS THEN PRINT "ERROR: MP OUT OF RANGE AT"I:END
327 : IF DB THEN PRINT "IP:"I"("I$") MP:"MP"("FNMP(MP)")"
330 : I$=MID$(P$,I,1)
340 : IF I$<>"(" AND I$<>"[" THEN 370
350 : IF FNMP(MP)=0 THEN I=B%(I)
360 : GOTO 480
370 : IF I$<>")" AND I$<>"]" THEN 400
380 : IF FNMP(MP) THEN I=B%(I)
390 : GOTO 480
400 : IF I$="<" THEN MP=MP-1:GOTO 480
410 : IF I$=">" THEN MP=MP+1:GOTO 480
420 : IF I$="-" THEN V=FNMP(MP)-1:GOTO 500
430 : IF I$="+" THEN V=FNMP(MP)+1:GOTO 500
440 : IF I$="." THEN ?CHR$(FNMP(MP));:GOTO 480
450 : IF I$<>"," THEN 480
460 : K$=INKEY$:IF K$="" THEN 460
470 : V=ASC(K$):GOTO 500
480 NEXT I
490 END
495 REM UPDATE CELL AT MP WITH VALUE IN V
500 M=INT(MP/2):O=M%(M):V=V AND 255
510 N0=(O AND -256)+V
520 N1=(V*256+(O AND 255))
530 M%(M) = (MP AND 1)*N1 - ((MP AND 1)=0)*N0
540 GOTO 480
545 REM HELLO, WORLD PROGRAM
570 DATA "+++++++++[>++++++++<-]>."
580 DATA "<+++++[>+++++<-]>++++."
590 DATA "+++++++..+++."
600 DATA ">>++++[<+++++++++++>-]<."
610 DATA ">++++[<--->-]<."
620 DATA "<++++++++."
630 DATA "--------."
640 DATA "+++."
650 DATA "------."
660 DATA "--------."
670 DATA ">>[++][<+++++++>-]<+."
680 DATA ">++++++++++."
690 DATA ""