在未经微软或比尔盖茨同意的情况下某人公开了1978年的Microsoft BASIC for 6502源代码，以及原始评论、文档和彩蛋，这是目前公开的比尔盖茨写的最古老程序。Michael Steil分析了源代码和文件后认为它可能是源自苹果的一位名叫David Craig的开发者。
TITLE BASIC M6502 8K VER 1.1 BY MICRO-SOFT
SEARCH M6502
SALL
RADIX 10 ;THROUGHOUT ALL BUT MATH-PAK.
$Z:: ;STARTING POINT FOR M6502 SIMULATOR
ORG 0 ;START OFF AT LOCATION ZERO.
SUBTTL SWITCHES,MACROS.
REALIO=4 ;5=STM
;4=APPLE.
;3=COMMODORE.
;2=OSI
;1=MOS TECH,KIM
;0=PDP-10 SIMULATING 6502
INTPRC==1 ;INTEGER ARRAYS.
ADDPRC==1 ;FOR ADDITIONAL PRECISION.
LNGERR==0 ;LONG ERROR MESSAGES.
TIME== 0 ;CAPABILITY TO SET AND READ A CLK.
EXTIO== 0 ;EXTERNAL I/O.
DISKO== 0 ;SAVE AND LOAD COMMANDS
NULCMD==1 ;FOR THE "NULL" COMMAND
GETCMD==1
RORSW==1
ROMSW==1 ;TELLS IF THIS IS ON ROM.
CLMWID==14
LONGI==1 ;LONG INITIALIZATION SWITCH.
STKEND=511
BUFPAG==0
LINLEN==72 ;TERMINAL LINE LENGTH.
BUFLEN==72 ;INPUT BUFFER SIZE.
ROMLOC= ^O20000 ;ADDRESS OF START OF PURE SEGMENT.
KIMROM=1
IFE ROMSW,<KIMROM==0>
IFN REALIO-1,<KIMROM==0>
IFN ROMSW,<
RAMLOC= ^O40000 ;USED ONLY IF ROMSW=1
IFE REALIO,<ROMLOC= ^O20000 ;START AT 8K.
RAMLOC=^O1400>>
IFE REALIO-3,<
DISKO==1
RAMLOC==^O2000
ROMLOC=^O140000
NULCMD==0
GETCMD==1
linlen==40
BUFLEN==81
CQOPEN=^O177700
CQCLOS=^O177703
CQOIN= ^O177706 ;OPEN CHANNEL FOR INPUT
CQOOUT=^O177711 ;FILL FOR COMMO.
CQCCHN=^O177714
CQINCH=^O177717 ;INCHR'S CALL TO GET A CHARACTER
OUTCH= ^O177722
CQLOAD=^O177725
CQSAVE=^O177730
CQVERF=^O177733
CQSYS= ^O177736
ISCNTC=^O177741
CZGETL=^O177744 ;CALL POINT FOR "GET"
CQCALL=^O177747 ;CLOSE ALL CHANNELS
CQTIMR=^O215
BUFPAG==2
BUF==256BUFPAG
STKEND==507
CQSTAT=^O226
CQHTIM=^O164104
EXTIO==1
TIME==1
GETCMD==1
CLMWID==10
PI=255 ;VALUE OF PI CHARACTER FOR COMMODORE.
ROMSW==1
RORSW==1
TRMPOS=^O306>
IFE REALIO-1,<GETCMD==1
DISKO==1
OUTCH=^O17240 ;1EA0
ROMLOC==^O20000
RORSW==0
CZGETL=^O17132>
IFE REALIO-2,<
RORSW==0
RAMLOC==^O1000
IFN ROMSW,<
RORSW==0
RAMLOC==^O100000>
OUTCH==^O177013>
IFE REALIO-4,<
RORSW==1
NULCMD==0
GETCMD==1
CQINLN==^O176547
CQPRMP==^O63
CQINCH==^O176414
CQCOUT==^O177315
CQCSIN==^O177375
BUFPAG==2
BUF=BUFPAG256
ROMLOC=^O4000
RAMLOC=^O25000 ;PAGE 2A
OUTCH=^O176755
CZGETL=^O176414
LINLEN==40
BUFLEN==240
RORSW==1
STKEND=507>
IFE RORSW,<
DEFINE ROR (WD),<
LDAI 0
BCC .+4
LDAI ^O200
LSR WD
ORA WD
STA WD>>
DEFINE ACRLF,<
13
10>
DEFINE SYNCHK (Q),<
LDAI <Q>
JSR SYNCHR>
DEFINE DT(Q),<
IRPC Q,<IFDIF <Q><">,<EXP "Q">>>
DEFINE LDWD (WD),<
LDA WD
LDY <WD>+1>
DEFINE LDWDI (WD),<
LDAI <<WD>&^O377>
LDYI <<WD>/^O400>>
DEFINE LDWX (WD),<
LDA WD
LDX <WD>+1>
DEFINE LDWXI (WD),<
LDAI <<WD>&^O377>
LDXI <<WD>/^O400>>
DEFINE LDXY (WD),<
LDX WD
LDY <WD>+1>
DEFINE LDXYI (WD),<
LDXI <<WD>&^O377>
LDYI <<WD>/^O400>>
DEFINE STWD (WD),<
STA WD
STY <WD>+1>
DEFINE STWX (WD),<
STA WD
STX <WD>+1>
DEFINE STXY (WD),<
STX WD
STY <WD>+1>
DEFINE CLR (WD),<
LDAI 0
STA WD>
DEFINE COM (WD),<
LDA WD
EORI ^O377
STA WD>
DEFINE PULWD (WD),<
PLA
STA WD
PLA
STA <WD>+1>
DEFINE PSHWD (WD),<
LDA <WD>+1
PHA
LDA WD
PHA>
DEFINE JEQ (WD),<
BNE .+5
JMP WD>
DEFINE JNE (WD),<
BEQ .+5
JMP WD>
DEFINE BCCA(Q),< BCC Q> ;BRANCHES THAT ALWAYS BRANCH
DEFINE BCSA(Q),< BCS Q> ;THESE ARE USED ON THE 6502 BECAUSE
DEFINE BEQA(Q),< BEQ Q> ;THERE IS NO UNCONDITIONAL BRANCH
DEFINE BNEA(Q),< BNE Q>
DEFINE BMIA(Q),< BMI Q>
DEFINE BPLA(Q),< BPL Q>
DEFINE BVCA(Q),< BVC Q>
DEFINE BVSA(Q),< BVS Q>
DEFINE INCW(R),<
INC R
BNE %Q
INC R+1
%Q:>
DEFINE SKIP1, <XWD ^O1000,^O044> ;BIT ZERO PAGE TRICK.
DEFINE SKIP2, <XWD ^O1000,^O054> ;BIT ABS TRICK.
IF1,<
IFE REALIO,<PRINTX/SIMULATE/>
IFE REALIO-1,<PRINTX KIM>
IFE REALIO-2,<PRINTX OSI>
IFE REALIO-3,<PRINTX COMMODORE>
IFE REALIO-4,<PRINTX APPLE>
IFE REALIO-5,<PRINTX STM>
IFN ADDPRC,<PRINTX ADDITIONAL PRECISION>
IFN INTPRC,<PRINTX INTEGER ARRAYS>
IFN LNGERR,<PRINTX LONG ERRORS>
IFN DISKO,<PRINTX SAVE AND LOAD>
IFE ROMSW,<PRINTX RAM>
IFN ROMSW,<PRINTX ROM>
IFE RORSW,<PRINTX NO ROR>
IFN RORSW,<PRINTX ROR ASSUMED>>
PAGE
SUBTTL INTRODUCTION AND COMPILATION PARAMETERS.
COMMENT
--------- ---- -- ---------
COPYRIGHT 1976 BY MICROSOFT
--------- ---- -- ---------
7/27/78 FIXED BUG WHERE FOR VARIABLE AT BYTE FF MATCHED RETURN SEARCHING
FOR GOSUB ENTRY ON STACK IN FNDFOR CALL BY CHANGING STA FORPNT
TO STA FORPNT+1. THIS IS A SERIOUS BUG IN ALL VERSIONS.
7/27/78 FIXED BUG AT NEWSTT UNDER IFN BUFPAG WHEN CHECK OF CURLIN
WAS DONE BEFORE CURLIN SET UP SO INPUT RETRIES OF FIRST STATEMENT
WAS GIVING SYNTAX ERROR INSTEAD OF REDO FROM START (CODE WAS 12/1/77 FIX)
7/1/78 SAVED A FEW BYTES IN INIT FOR COMMODORE (14)
7/1/78 FIXED BUG WHERE REPLACING A LINE OVERFLOWING MEMORY LEFT LINKS
IN A BAD STATE. (CODE AT NODEL AND FINI) BUG#4
7/1/78 FIXED BUG WHERE GARBAGE COLLECTION NEVER(!) COLLECTS TEMPS
(STY GRBPNT AT FNDVAR, LDA GRBPNT ORA GRBPNT+1 AT GRBPAS)
THIS WAS COMMODORE BUG #2
7/1/78 FIXED BUG WHERE DELETE/INSERT OF LINE COULD CAUSE A GARBAGE COLLECTION WITH BAD VARTAB IF OUT OF MEMORY
(LDWD MEMSIZ STWD FRETOP=JSR RUNC CLC ALSO AT NODEL)
3/9/78 EDIT TO FIX COMMO TRMPOS AND CHANGE LEFT$ AND RIGHT$ TO ALLOW A SECOND ARGUMENT OF 0 AND RETURN A NULL STRING
2/25/78 FIXED BUG THAT INPFLG WAS SET WRONG WHEN BUFPAG.NE.0
INCREASED NUMLEV FROM 19 TO 23
2/11/78 DISALLOWED SPACES IN RESERVED WORDS. PUT IN SPECIAL CHECK FOR "GO TO"
2/11/78 FIXED BUG WHERE ROUNDING OF THE FAC BEFORE PUSHING COULD CAUSE A STRING POINTER
IN THE FAC TO BE INCREMENTED
1/24/78 fixed problem where user defined function undefined check fix was smashing error number in [x]
12/1/77 FIXED PROBLEM WHERE PEEK WAS SMASHING (POKER) CAUSING POKE OF PEEK TO FAIL
12/1/77 FIXED PROBLEM WHERE PROBLEM WITH VARTXT=LINNUM=BUF-2 CAUSING BUF-1 COMMA TO DISAPPEAR
12/1/77 FIXED BUFPAG.NE.0 PROBLEM AT NEWSTT AND STOP : CODE WAS STILL
ASSUMING TXTPTR+1.EQ.0 IFF STATEMENT WAS DIRECT
NUMLEV==23 ;NUMBER OF STACK LEVELS RESERVED
;BY AN EXPLICIT CALL TO "GETSTK".
STRSIZ==3 ;# OF LOCS PER STRING DESCRIPTOR.
NUMTMP==3 ;NUMBER OF STRING TEMPORARIES.
CONTW==15 ;CHARACTER TO SUPPRESS OUTPUT.
PAGE
SUBTTL SOME EXPLANATION.
COMMENT
M6502 BASIC CONFIGURES BASIC AS FOLLOWS
LOW LOCATIONS
PAGE ZERO
STARTUP:
INITIALLY A JMP TO INITIALIZATION CODE BUT
CHANGED TO A JMP TO "READY".
RESTARTING THE MACHINE AT LOC 0 DURING PROGRAM
EXECUTION CAN LEAVE THINGS MESSED UP.
LOC OF FAC TO INTEGER AND INTEGER TO FAC
ROUTINES.
"DIRECT" MEMORY:
THESE ARE THE MOST COMMONLY USED LOCATIONS.
THEY HOLD BOOKKEEPING INFO AND ALL OTHER
FREQUENTLY USED INFORMATION.
ALL TEMPORARIES, FLAGS, POINTERS, THE BUFFER AREA,
THE FLOATING ACCUMULATOR, AND ANYTHING ELSE THAT
IS USED TO STORE A CHANGING VALUE SHOULD BE LOCATED
IN THIS AREA. CARE MUST BE MADE IN MOVING LOCATIONS
IN THIS AREA SINCE THE JUXTAPOSITION OF TWO LOCATIONS
IS OFTEN DEPENDED UPON.
STILL IN RAM WE HAVE THE BEGINNING OF THE "CHRGET"
SUBROUTINE. IT IS HERE SO [TXTPTR] CAN BE THE
EXTENDED ADDRESS OF A LOAD INSTRUCTION.
THIS SAVES HAVING TO BOTHER ANY REGISTERS.
PAGE ONE
THE STACK.
STORAGE PAGE TWO AND ON
IN RAM VERSIONS THESE DATA STRUCTURES COME AT THE
END OF BASIC. IN ROM VERSON THEY ARE AT RAMLOC WHICH
CAN EITHER BE ABOVE OR BELOW ROMLOC, WHICH IS WHERE
BASIC ITSELF RESIDES.
A ZERO.
[TXTTAB] POINTER TO NEXT LINE'S POINTER.
LINE # OF THIS LINE (2 BYTES).
CHARACTERS ON THIS LINE.
ZERO.
POINTER AT NEXT LINE'S POINTER
(POINTED TO BY THE ABOVE POINTER).
... REPEATS ...
LAST LINE: POINTER AT ZERO POINTER.
LINE # OF THIS LINE.
CHARACTERS ON THIS LINE.
ZERO.
DOUBLE ZERO (POINTED TO BY THE ABOVE POINTER).
[VARTAB] SIMPLE VARIABLES. 6 BYTES PER VALUE.
2 BYTES GIVE THE NAME, 4 BYTES THE VALUE.
... REPEATS ...
[ARYTAB] ARRAY VARIABLES. 2 BYTES NAME, 2 BYTE
LENGTH, NUMBER OF DIMENSIONS , EXTENT OF
EACH DIMENSION (2BYTES/), VALUES
... REPEATS ...
[STREND] FREE SPACE.
... REPEATS ...
[FRETOP] STRING SPACE IN USE.
... REPEATS ...
[MEMSIZ] HIGHEST MACHINE LOCATION.
UNUSED EXCEPT BY THE VAL FUNCTION.
ROM -- CONSTANTS AND CODE.
FUNCTION DISPATCH ADDRESSES (AT ROMLOC)
"FUNDSP" CONTAINS THE ADDRESSES OF THE
FUNCTION ROUTINES IN THE ORDER OF THE
FUNCTION NAMES IN THE CRUNCH LIST.
THE FUNCTIONS THAT TAKE MORE THAN ONE ARGUMENT
ARE AT THE END. SEE THE EXPLANATION AT "ISFUN".
THE OPERATOR LIST
THE "OPTAB" LIST CONTAINS AN OPERATOR'S PRECEDENCE
FOLLOWED BY THE ADDRESS OF THE ROUTINE TO PERFORM
THE OPERATION. THE INDEX INTO THE
OPERATOR LIST IS MADE BY SUBTRACTING OFF THE CRUNCH VALUE
OF THE LOWEST NUMBERED OPERATOR. THE ORDER
OF OPERATORS IN THE CRUNCH LIST AND IN "OPTAB" IS IDENTICAL.
THE PRECEDENCES ARE ARBITRARY EXCEPT FOR THEIR
COMPARATIVE SIZES. NOTE THAT THE PRECEDENCE FOR
UNARY OPERATORS SUCH AS "NOT" AND NEGATION ARE
SETUP SPECIALLY WITHOUT USING THE LIST.
THE RESERVED WORD OR CRUNCH LIST
WHEN A COMMAND OR PROGRAM LINE IS TYPED IN
IT IS STORED IN "BUF". AS SOON AS THE WHOLE LINE
HAS BEEN TYPED IN ("INLIN" RETURNS) "CRUNCH" IS
CALLED TO CONVERT ALL RESERVED WORDS TO THEIR
CRUNCHED VALUES. THIS REDUCES THE SIZE OF THE
PROGRAM AND SPEEDS UP EXECUTION BY ALLOWING
LIST DISPATCHES TO PERFORM FUNCTIONS, STATEMENTS,
AND OPERATIONS. THIS IS BECAUSE ALL THE STATEMENT
NAMES ARE STORED CONSECUTIVELY IN THE CRUNCH LIST.
WHEN A MATCH IS FOUND BETWEEN A STRING
OF CHARACTERS AND A WORD IN THE CRUNCH LIST
THE ENTIRE TEXT OF THE MATCHED WORD IS TAKEN OUT OF
THE INPUT LINE AND A RESERVED WORD TOKEN IS PUT
IN ITS PLACE. A RESERVED WORD TOKEN IS ALWAYS EQUAL
TO OCTAL 200 PLUS THE POSITION OF THE MATCHED WORD
IN THE CRUNCH LIST.
STATEMENT DISPATCH ADDRESSES
WHEN A STATEMENT IS TO BE EXECUTED, THE FIRST
CHARACTER OF THE STATEMENT IS EXAMINED
TO SEE IF IT IS LESS THAN THE RESERVED
WORD TOKEN FOR THE LOWEST NUMBERED STATEMENT NAME.
IF SO, THE "LET" CODE IS CALLED TO
TREAT THE STATEMENT AS AN ASSIGNMENT STATEMENT.
OTHERWISE A CHECK IS MADE TO MAKE SURE THE
RESERVED WORD NUMBER IS NOT TOO LARGE TO BE A
STATEMENT TYPE NUMBER. IF NOT THE ADDRESS
TO DISPATCH TO IS FETCHED FROM "STMDSP" (THE STATEMENT
DISPATCH LIST) USING THE RESERVED WORD
NUMBER FOR THE STATEMENT TO CALCULATE AN INDEX INTO
THE LIST.
ERROR MESSAGES
WHEN AN ERROR CONDITION IS DETECTED,
[ACCX] MUST BE SET UP TO INDICATE WHICH ERROR
MESSAGE IS APPROPRIATE AND A BRANCH MUST BE MADE
TO "ERROR". THE STACK WILL BE RESET AND ALL
PROGRAM CONTEXT WILL BE LOST. VARIABLES
VALUES AND THE ACTUAL PROGRAM REMAIN INTACT.
ONLY THE VALUE OF [ACCX] IS IMPORTANT WHEN
THE BRANCH IS MADE TO ERROR. [ACCX] IS USED AS AN
INDEX INTO "ERRTAB" WHICH GIVES THE TWO
CHARACTER ERROR MESSAGE THAT WILL BE PRINTED ON THE
USER'S TERMINAL.
TEXTUAL MESSAGES
CONSTANT MESSAGES ARE STORED HERE. UNLESS
THE CODE TO CHECK IF A STRING MUST BE COPIED
IS CHANGED THESE STRINGS MUST BE STORED ABOVE
PAGE ZERO, OR ELSE THEY WILL BE COPIED BEFORE
THEY ARE PRINTED.
FNDFOR
MOST SMALL ROUTINES ARE FAIRLY SIMPLE
AND ARE DOCUMENTED IN PLACE. "FNDFOR" IS
USED FOR FINDING "FOR" ENTRIES ON
THE STACK. WHENEVER A "FOR" IS EXECUTED, A
16-BYTE ENTRY IS PUSHED ONTO THE STACK.
BEFORE THIS IS DONE, HOWEVER, A CHECK
MUST BE MADE TO SEE IF THERE
ARE ANY "FOR" ENTRIES ALREADY ON THE STACK
FOR THE SAME LOOP VARIABLE. IF SO, THAT "FOR" ENTRY
AND ALL OTHER "FOR" ENTRIES THAT WERE MADE AFTER IT
ARE ELIMINATED FROM THE STACK. THIS IS SO A
PROGRAM THAT JUMPS OUT OF THE MIDDLE
OF A "FOR" LOOP AND THEN RESTARTS THE LOOP AGAIN
AND AGAIN WON'T USE UP 18 BYTES OF STACK
SPACE EVERY TIME. THE "NEXT" CODE ALSO
CALLS "FNDFOR" TO SEARCH FOR A "FOR" ENTRY WITH
THE LOOP VARIABLE IN
THE "NEXT". AT WHATEVER POINT A MATCH IS FOUND
THE STACK IS RESET. IF NO MATCH IS FOUND A
"NEXT WITHOUT FOR" ERROR OCCURS. GOSUB EXECUTION
ALSO PUTS A 5-BYTE ENTRY ON STACK.
WHEN A RETURN IS EXECUTED "FNDFOR" IS
CALLED WITH A VARIABLE POINTER THAT CAN'T
BE MATCHED. WHEN "FNDFOR" HAS RUN
THROUGH ALL THE "FOR" ENTRIES ON THE STACK
IT RETURNS AND THE RETURN CODE MAKES
SURE THE ENTRY THAT WAS STOPPED
ON IS A GOSUB ENTRY. THIS ASSURES THAT
IF YOU GOSUB TO A SECTION OF CODE
IN WHICH A FOR LOOP IS ENTERED BUT NEVER
EXITED THE RETURN WILL STILL BE
ABLE TO FIND THE MOST RECENT
GOSUB ENTRY. THE "RETURN" CODE ELIMINATES THE
"GOSUB" ENTRY AND ALL "FOR" ENTRIES MADE AFTER
THE GOSUB ENTRY.
NON-RUNTIME STUFF
THE CODE TO INPUT A LINE, CRUNCH IT, GIVE ERRORS,
FIND A SPECIFIC LINE IN THE PROGRAM,
PERFORM A "NEW", "CLEAR", AND "LIST" ARE
ALL IN THIS AREA. GIVEN THE EXPLANATION OF
PROGRAM STORAGE SET FORTH ABOVE, THESE ARE
ALL STRAIGHTFORWARD.
NEWSTT
WHENEVER A STATEMENT FINISHES EXECUTION IT
DOES A "RTS" WHICH TAKES
EXECUTION BACK TO "NEWSTT". STATEMENTS THAT
CREATE OR LOOK AT SEMI-PERMANENT STACK ENTRIES
MUST GET RID OF THE RETURN ADDRESS OF "NEWSTT" AND
JMP TO "NEWSTT" WHEN DONE. "NEWSTT" ALWAYS
CHRGETS THE FIRST CHARACTER AFTER THE STATEMENT
NAME BEFORE DISPATCHING. WHEN RETURNING
BACK TO "NEWSTT" THE ONLY THING THAT
MUST BE SET UP IS THE TEXT POINTER IN
"TXTPTR". "NEWSTT" WILL CHECK TO MAKE SURE
"TXTPTR" IS POINTING TO A STATEMENT TERMINATOR.
IF A STATEMENT SHOULDN'T BE PERFORMED UNLESS
IT IS PROPERLY FORMATTED (I.E. "NEW") IT CAN
SIMPLY DO A RETURN AFTER READING ALL OF
ITS ARGUMENTS. SINCE THE ZERO FLAG
BEING OFF INDICATES THERE IS NOT
A STATEMENT TERMINATOR "NEWSTT" WILL
DO THE JMP TO THE "SYNTAX ERROR"
ROUTINE. IF A STATEMENT SHOULD BE STARTED
OVER IT CAN DO LDWD OLDTXT, STWD TXTPTR RTS SINCE THE TEXT PNTR
AT "NEWSTT" IS ALWAYS STORED IN "OLDTXT".
THE ^C CODE STORES [CURLIN] (THE
CURRENT LINE NUMBER) IN "OLDLIN" SINCE THE ^C CHECK
IS MADE BEFORE THE STATEMENT POINTED TO IS
EXECUTED. "STOP" AND "END" STORE THE TEXT POINTER
FROM "TXTPTR", WHICH POINTS AT THEIR TERMINATING
CHARACTER, IN "OLDTXT".
STATEMENT CODE
THE INDIVIDUAL STATEMENT CODE COMES
NEXT. THE APPROACH USED IN EXECUTING EACH
STATEMENT IS DOCUMENTED IN THE STATEMENT CODE
ITSELF.
FRMEVL, THE FORMULA EVALUATOR
GIVEN A TEXT POINTER POINTING TO THE STARTING
CHARACTER OF A FORMULA, "FRMEVL"
EVALUATES THE FORMULA AND LEAVES
THE VALUE IN THE FLOATING ACCUMULATOR (FAC).
"TXTPTR" IS RETURNED POINTING TO THE FIRST CHARACTER
THAT COULD NOT BE INTERPRETED AS PART OF THE
FORMULA. THE ALGORITHM USES THE STACK
TO STORE TEMPORARY RESULTS:
0. PUT A DUMMY PRECEDENCE OF ZERO ON
THE STACK.
1. READ LEXEME (CONSTANT,FUNCTION,
VARIABLE,FORMULA IN PARENS)
AND TAKE THE LAST PRECEDENCE VALUE
OFF THE STACK.
2. SEE IF THE NEXT CHARACTER IS AN OPERATOR.
IF NOT, CHECK PREVIOUS ONE. THIS MAY CAUSE
OPERATOR APPLICATION OR AN ACTUAL
RETURN FROM "FRMEVL".
3. IF IT IS, SEE WHAT PRECEDENCE IT HAS
AND COMPARE IT TO THE PRECEDENCE
OF THE LAST OPERATOR ON THE STACK.
4. IF = OR LESS REMEMBER THE OPERATOR
POINTER OF THIS OPERATOR
AND BRANCH TO "QCHNUM" TO CAUSE
APPLICATION OF THE LAST OPERATOR.
EVENTUALLY RETURN TO STEP 2
BY RETURNING TO JUST AFTER "DOPREC".
5. IF GREATER PUT THE LAST PRECEDENCE
BACK ON, SAVE THE OPERATOR ADDRESS,
CURRENT TEMPORARY RESULT,
AND PRECEDENCE AND RETURN TO STEP 1.
RELATIONAL OPERATORS ARE ALL HANDLED THROUGH
A COMMON ROUTINE. SPECIAL
CARE IS TAKEN TO DETECT TYPE MISMATCHES SUCH AS 3+"F".
EVAL -- THE ROUTINE TO READ A LEXEME
"EVAL" CHECKS FOR THE DIFFERENT TYPES OF
ENTITIES IT IS SUPPOSED TO DETECT.
LEADING PLUSES ARE IGNORED,
DIGITS AND "." CAUSE "FIN" (FLOATING INPUT)
TO BE CALLED. FUNCTION NAMES CAUSE THE
FORMULA INSIDE THE PARENTHESES TO BE EVALUATED
AND THE FUNCTION ROUTINE TO BE CALLED. VARIABLE
NAMES CAUSE "PTRGET" TO BE CALLED TO GET A POINTER
TO THE VALUE, AND THEN THE VALUE IS PUT INTO
THE FAC. AN OPEN PARENTHESIS CAUSES "FRMEVL"
TO BE CALLED (RECURSIVELY), AND THE ")" TO
BE CHECKED FOR. UNARY OPERATORS (NOT AND
NEGATION) PUT THEIR PRECEDENCE ON THE STACK
AND ENTER FORMULA EVALUATION AT STEP 1, SO
THAT EVERYTHING UP TO AN OPERATOR GREATER THAN
THEIR PRECEDENCE OR THE END OF THE FORMULA
WILL BE EVALUATED.
DIMENSION AND VARIABLE SEARCHING
SPACE IS ALLOCATED FOR VARIABLES AS THEY ARE
ENCOUNTERED. THUS "DIM" STATEMENTS MUST BE
EXECUTED TO HAVE EFFECT. 6 BYTES ARE ALLOCATED
FOR EACH SIMPLE VARIABLE, WHETHER IT IS A STRING,
NUMBER OR USER DEFINED FUNCTION. THE FIRST TWO
BYTES GIVE THE NAME OF THE VARIABLE AND THE LAST FOUR
GIVE ITS VALUE. [VARTAB] GIVES THE FIRST LOCATION
WHERE A SIMPLE VARIABLE NAME IS FOUND AND [ARYTAB]
GIVES THE LOCATION TO STOP SEARCHING FOR SIMPLE
VARIABLES. A "FOR" ENTRY HAS A TEXT POINTER
AND A POINTER TO A VARIABLE VALUE SO NEITHER
THE PROGRAM OR THE SIMPLE VARIABLES CAN BE
MOVED WHILE THERE ARE ACTIVE "FOR" ENTRIES ON THE STACK.
USER DEFINED FUNCTION VALUES ALSO CONTAIN
POINTERS INTO SIMPLE VARIABLE SPACE SO NO USER-DEFINED
FUNCTION VALUES CAN BE RETAINED IF SIMPLE VARIABLES
ARE MOVED. ADDING A SIMPLE VARIABLE IS JUST
ADDING SIX TO [ARYTAB] AND [STREND], BLOCK TRANSFERING
THE ARRAY VARIABLES UP BY SIX AND MAKING SURE THE
NEW [STREND] IS NOT TOO CLOSE TO THE STRINGS.
THIS MOVEMENT OF ARRAY VARIABLES MEANS
THAT NO POINTER TO AN ARRAY WILL STAY VALID WHEN
NEW SIMPLE VARIABLES CAN BE ENCOUNTERED. THIS IS
WHY ARRAY VARIABLES ARE NOT ALLOWED FOR "FOR"
LOOP VARIABLES. SETTING UP A NEW ARRAY VARIABLE
MERELY INVOLVES BUILDING THE DESCRIPTOR,
UPDATING [STREND], AND MAKING SURE THERE IS
STILL ENOUGH ROOM BETWEEN [STREND] AND STRING SPACE.
"PTRGET", THE ROUTINE WHICH RETURNS A POINTER
TO A VARIABLE VALUE, HAS TWO IMPORTANT FLAGS. ONE IS
"DIMFLG" WHICH INDICATES WHETHER "DIM" CALLED "PTRGET"
OR NOT. IF SO, NO PRIOR ENTRY FOR THE VARIABLE IN
QUESTION SHOULD BE FOUND, AND THE INDEX INDICATES
HOW MUCH SPACE TO SET ASIDE. SIMPLE VARIABLES CAN
BE "DIMENSIONED", BUT THE ONLY EFFECT WILL BE TO
SET ASIDE SPACE FOR THE VARIABLE IF IT HASN'T BEEN
ENCOUNTERED YET. THE OTHER IMPORTANT FLAG IS "SUBFLG"
WHICH INDICATES WHETHER A SUBSCRIPTED VARIABLE SHOULD BE
ALLOWED IN THE CURRENT CONTEXT. IF [SUBFLG] IS NON-ZERO
THE OPEN PARENTHESIS FOR A SUBSCRIPTED VARIABLE
WILL NOT BE SCANNED BY "PTRGET", AND "PTRGET" WILL RETURN
WITH A TEXT POINTER POINTING TO THE "(", IF
THERE WAS ONE.
STRINGS
IN THE VARIABLE TABLES STRINGS ARE STORED JUST LIKE
NUMERIC VARIABLES. SIMPLE STRINGS HAVE THREE VALUE
BYTES WHICH ARE INITIALIZED TO ALL ZEROS (WHICH
REPRESENTS THE NULL STRING). THE ONLY DIFFERENCE
IN HANDLING IS THAT WHEN "PTRGET" SEES A "$" AFTER THE
NAME OF A VARIABLE, "PTRGET" SETS [VALTYP]
TO NEGATIVE ONE AND TURNS
ON THE MSB (MOST-SIGNIFIGANT-BIT) OF THE VALUE OF
THE FIRST CHARACTER OF THE VARIABLE NAME.
HAVING THIS BIT ON IN THE NAME OF THE VARIABLE ENSURES
THAT THE SEARCH ROUTINE WILL NOT MATCH
'A' WITH 'A$' OR 'A$' WITH 'A'. THE MEANING OF
THE THREE VALUE BYTES ARE:
LOW
LENGTH OF THE STRING
LOW 8 BITS
HIGH 8 BITS OF THE ADDRESS
OF THE CHARACTERS IN THE
STRING IF LENGTH.NE.0.
MEANINGLESS OTHERWISE.
HIGH
THE VALUE OF A STRING VARIABLE (THESE 3 BYTES)
IS CALLED THE STRING DESCRIPTOR TO DISTINGUISH
IT FROM THE ACTUAL STRING DATA. WHENEVER A
STRING CONSTANT IS ENCOUNTERED IN A FORMULA OR AS
PART OF AN INPUT STRING, OR AS PART OF DATA, "STRLIT"
IS CALLED, CAUSING A DESCRIPTOR TO BE BUILT FOR
THE STRING. WHEN ASSIGNMENT IS MADE TO A STRING POINTING INTO
"BUF" THE VALUE IS COPIED INTO STRING SPACE SINCE [BUF]
IS ALWAYS CHANGING.
STRING FUNCTIONS AND THE ONE STRING OPERATOR "+"
ALWAYS RETURN THEIR VALUES IN STRING SPACE.
ASSIGNING A STRING A CONSTANT VALUE IN A PROGRAM
THROUGH A "READ" OR ASSIGNMENT STATEMENT
WILL NOT USE ANY STRING SPACE SINCE
THE STRING DESCRIPTOR WILL POINT INTO THE
PROGRAM ITSELF. IN GENERAL, COPYING IS DONE
WHEN A STRING VALUE IS IN "BUF", OR IT IS IN STRING
SPACE AND THERE IS AN ACTIVE POINTER TO IT.
THUS F$=G$ WILL CAUSE COPYING IF G$ HAS ITS
STRING DATA IN STRING SPACE. F$=CHR$(7)
WILL USE ONE BYTE OF STRING SPACE TO STORE THE
NEW ONE CHARACTER STRING CREATED BY "CHR$", BUT
THE ASSIGNMENT ITSELF WILL CAUSE NO COPYING SINCE
THE ONLY POINTER AT THE NEW STRING IS A
TEMPORARY DESCRIPTOR CREATED BY "FRMEVL" WHICH WILL
GO AWAY AS SOON AS THE ASSIGNMENT IS DONE.
IT IS THE NATURE OF GARBAGE COLLECTION THAT
DISALLOWS HAVING TWO STRING DESCRIPTORS POINT TO THE SAME
AREA IN STRING SPACE. STRING FUNCTIONS AND OPERATORS
MUST PROCEED AS FOLLOWS:
1) FIGURE OUT THE LENGTH OF THEIR RESULT.
2) CALL "GETSPA" TO FIND SPACE FOR THEIR
RESULT. THE ARGUMENTS TO THE FUNCTION
OR OPERATOR MAY CHANGE SINCE GARBAGE COLLECTION
MAY BE INVOKED. THE ONLY THING THAT CAN
BE SAVED DURING THE CALL TO "GETSPA" IS A POINTER
TO THE DESCRIPTORS OF THE ARGUMENTS.
3) CONSTRUCT THE RESULT DESCRIPTOR IN "DSCTMP".
"GETSPA" RETURNS THE LOCATION OF THE AVAILABLE
SPACE.
4) CREATE THE NEW VALUE BY COPYING PARTS
OF THE ARGUMENTS OR WHATEVER.
5) FREE UP THE ARGUMENTS BY CALLING "FRETMP".
6) JUMP TO "PUTNEW" TO GET THE DESCRIPTOR IN
"DSCTMP" TRANSFERRED INTO A NEW STRING TEMPORARY.
THE REASON FOR STRING TEMPORARIES IS THAT GARBAGE
COLLECTION HAS TO KNOW ABOUT ALL ACTIVE STRING DESCRIPTORS
SO IT KNOWS WHAT IS AND ISN'T IN USE. STRING TEMPORARIES ARE
USED TO STORE THE DESCRIPTORS OF STRING EXPRESSIONS.
INSTEAD OF HAVING AN ACTUAL VALUE STORED IN THE
FAC, AND HAVING THE VALUE OF A TEMPORARY RESULT
BEING SAVED ON THE STACK, AS HAPPENS WITH NUMERIC
VARIABLES, STRINGS HAVE THE POINTER TO A STRING DESCRIPTOR
STORED IN THE FAC, AND IT IS THIS POINTER
THAT GETS SAVED ON THE STACK BY FORMULA EVALUATION.
STRING FUNCTIONS CANNOT FREE THEIR ARGUMENTS UP RIGHT
AWAY SINCE "GETSPA" MAY FORCE
GARBAGE COLLECTION AND THE ARGUMENT STRINGS
MAY BE OVER-WRITTEN SINCE GARBAGE COLLECTION
WILL NOT BE ABLE TO FIND AN ACTIVE POINTER TO
THEM. FUNCTION AND OPERATOR RESULTS ARE BUILT IN
"DSCTMP" SINCE STRING TEMPORARIES ARE ALLOCATED
(PUTNEW) AND DEALLOCATED (FRETMP) IN A FIFO ORDERING
(I.E. A STACK) SO THE NEW TEMPORARY CANNOT
BE SET UP UNTIL THE OLD ONE(S) ARE FREED. TRYING
TO BUILD A RESULT IN A TEMPORARY AFTER
FREEING UP THE ARGUMENT TEMPORARIES COULD RESULT
IN ONE OF THE ARGUMENT TEMPORARIES BEING OVERWRITTEN
TOO SOON BY THE NEW RESULT.
STRING SPACE IS ALLOCATED AT THE VERY TOP
OF MEMORY. "MEMSIZ" POINTS BEYOND THE LAST LOCATION OF
STRING SPACE. STRINGS ARE STORED IN HIGH LOCATIONS
FIRST. WHENEVER STRING SPACE IS ALLOCATED (GETSPA).
[FRETOP], WHICH IS INITIALIZED TO [MEMSIZ], IS UPDATED
TO GIVE THE HIGHEST LOCATION IN STRING SPACE
THAT IS NOT IN USE. THE RESULT IS THAT
[FRETOP] GETS SMALLER AND SMALLER, UNTIL SOME
ALLOCATION WOULD MAKE [FRETOP] LESS THAN OR EQUAL TO
[STREND]. THIS MEANS STRING SPACE HAS RUN INTO THE
THE ARRAYS AND THAT GARBAGE COLLECTION MUST BE CALLED.
GARBAGE COLLECTION:
0. [MINPTR]=[STREND] [FRETOP]=[MEMSIZ]
1. [REMMIN]=0
2. FOR EACH STRING DESCRIPTOR
(TEMPORARIES, SIMPLE STRINGS, STRING ARRAYS)
IF THE STRING IS NOT NULL AND ITS POINTER IS
.GT.MINPTR AND .LT.FRETOP,
[MINPTR]=THIS STRING DESCRIPTOR'S POINTER,
[REMMIN]=POINTER AT THIS STRING DESCRIPTOR.
END.
3. IF REMMIN.NE.0 (WE FOUND AN UNCOLLECTED STRING),
BLOCK TRANSFER THE STRING DATA POINTED
TO IN THE STRING DESCRIPTOR POINTED TO BY "REMMIN"
SO THAT THE LAST BYTE OF STRING DATA IS AT
[FRETOP]. UPDATE [FRETOP] SO THAT IT
POINTS TO THE LOCATION JUST BELOW THE ONE
THE STRING DATA WAS MOVED INTO. UPDATE
THE POINTER IN THE DESCRIPTOR SO IT POINTS
TO THE NEW LOCATION OF THE STRING DATA.
GO TO STEP 1.
AFTER CALLING GARBAGE COLLECTION "GETSPA" AGAIN CHECKS
TO SEE IF [ACCA] CHARACTERS ARE AVAILABLE BETWEEN
[STREND] AND [FRETOP]; IF NOT, AN "OUT OF STRING"
ERROR IS INVOKED.
MATH PACKAGE
THE MATH PACKAGE CONTAINS FLOATING INPUT (FIN),
FLOATING OUTPUT (FOUT), FLOATING COMPARE (FCOMP)
... AND ALL THE NUMERIC OPERATORS AND FUNCTIONS.
THE FORMATS, CONVENTIONS AND ENTRY POINTS ARE ALL
DESCRIBED IN THE MATH PACKAGE ITSELF.
INIT -- THE INITIALIZATION ROUTINE
THE AMOUNT OF MEMORY,
TERMINAL WIDTH, AND WHICH FUNCTIONS TO BE RETAINED
ARE ASCERTAINED FROM THE USER. A ZERO IS PUT DOWN
AT THE FIRST LOCATION NOT USED BY THE MATH-PACKAGE
AND [TXTTAB] IS SET UP TO POINT AT THE NEXT LOCATION.
THIS DETERMINES WHERE PROGRAM STORAGE WILL START.
SPECIAL CHECKS ARE MADE TO MAKE SURE
ALL QUESTIONS IN "INIT" ARE ANSWERED REASONABLY, SINCE
ONCE "INIT" FINISHES, THE LOCATIONS IT USES ARE
USED FOR PROGRAM STORAGE. THE LAST THING "INIT" DOES IS
CHANGE LOCATION ZERO TO BE A JUMP TO "READY" INSTEAD
OF "INIT". ONCE THIS IS DONE THERE IS NO WAY TO RESTART
"INIT".
HIGH LOCATIONS
PAGE
SUBTTL PAGE ZERO.
IFN REALIO-3,<
START: JMP INIT ;INITIALIZE - SETUP CERTAIN LOCATIONS
;AND DELETE FUNCTIONS IF NOT NEEDED,
;AND CHANGE THIS TO "JMP READY"
;IN CASE USER RESTARTS AT LOC ZERO.
RDYJSR: JMP INIT ;CHANGED TO "JMP STROUT" BY "INIT"
;TO HANDLE ERRORS.
ADRAYI: ADR(AYINT) ;STORE HERE THE ADDR OF THE
;ROUTINE TO TURN THE FAC INTO A
;TWO BYTE SIGNED INTEGER IN [Y,A]
ADRGAY: ADR(GIVAYF)> ;STORE HERE THE ADDR OF THE
;ROUTINE TO CONVERT [Y,A] TO A FLOATING
;POINT NUMBER IN THE FAC.
IFN ROMSW,<
USRPOK: JMP FCERR> ;SET UP ORIG BY INIT.
;
; THIS IS THE "VOLATILE" STORAGE AREA AND NONE OF IT
; CAN BE KEPT IN ROM. ANY CONSTANTS IN THIS AREA CANNOT
; BE KEPT IN A ROM, BUT MUST BE LOADED IN BY THE
; PROGRAM INSTRUCTIONS IN ROM.
;
; --- GENERAL RAM ---:
CHARAC: BLOCK 1 ;A DELIMITING CHARACTER.
INTEGR= CHARAC ;A ONE-BYTE INTEGER FROM "QINT".
ENDCHR: BLOCK 1 ;THE OTHER DELIMITING CHARACTER.
COUNT: BLOCK 1 ;A GENERAL COUNTER.
; --- FLAGS ---:
DIMFLG: BLOCK 1 ;IN GETTING A POINTER TO A VARIABLE
;IT IS IMPORTANT TO REMEMBER WHETHER IT
;IS BEING DONE FOR "DIM" OR NOT.
;DIMFLG AND VALTYP MUST BE
;CONSECUTIVE LOCATIONS.
KIMY= DIMFLG ;PLACE TO PRESERVE Y DURING OUT.
VALTYP: BLOCK 1 ;THE TYPE INDICATOR.
;0=NUMERIC 1=STRING.
IFN INTPRC,<
INTFLG: BLOCK 1> ;TELLS IF INTEGER.
DORES: BLOCK 1 ;WHETHER CAN OR CAN'T CRUNCH RES'D WORDS.
;TURNED ON WHEN "DATA"
;BEING SCANNED BY CRUNCH SO UNQUOTED
;STRINGS WON'T BE CRUNCHED.
GARBFL= DORES ;WHETHER TO DO GARBAGE COLLECTION.
SUBFLG: BLOCK 1 ;FLAG WHETHER SUB'D VARIABLE ALLOWED.
;"FOR" AND USER-DEFINED FUNCTION
;POINTER FETCHING TURN
;THIS ON BEFORE CALLING "PTRGET"
;SO ARRAYS WON'T BE DETECTED.
;"STKINI" AND "PTRGET" CLEAR IT.
;ALSO DISALLOWS INTEGERS THERE.
INPFLG: BLOCK 1 ;FLAGS WHETHER WE ARE DOING "INPUT"
;OR "READ".
TANSGN: BLOCK 1 ;USED IN DETERMINING SIGN OF TANGENT.
IFN REALIO,<
CNTWFL: BLOCK 1> ;SUPPRESS OUTPUT FLAG.
;NON-ZERO MEANS SUPPRESS.
;RESET BY "INPUT", READY AND ERRORS.
;COMPLEMENTED BY INPUT OF ^O.
IFE REALIO-4,<ORG 80> ;ROOM FOR APPLE PAGE 0 STUFF.
; --- RAM DEALING WITH TERMINAL HANDLING ---:
IFN EXTIO,<
CHANNL: BLOCK 1> ;HOLDS CHANNEL NUMBER.
IFN NULCMD,<
NULCNT: 0> ;NUMBER OF NULLS TO PRINT.
IFN REALIO-3,<
TRMPOS: BLOCK 1> ;POSITION OF TERMINAL CARRIAGE.
LINWID: LINLEN ;LENGTH OF LINE (WIDTH).
NCMWID: NCMPOS ;POSITION BEYOND WHICH THERE ARE
;NO MORE FIELDS.
LINNUM: 0 ;LOCATION TO STORE LINE NUMBER BEFORE BUF
;SO THAT "BLTUC" CAN STORE IT ALL AWAY AT ONCE.
44 ;A COMMA (PRELOAD OR FROM ROM)
;USED BY INPUT STATEMENT SINCE THE
;DATA POINTER ALWAYS STARTS ON A
;COMMA OR TERMINATOR.
IFE BUFPAG,<
BUF: BLOCK BUFLEN> ;TYPE IN STORED HERE.
;DIRECT STATEMENTS EXECUTE OUT OF
;HERE. REMEMBER "INPUT" SMASHES BUF.
;MUST BE ON PAGE ZERO
;OR ASSIGNMENT OF STRING
;VALUES IN DIRECT STATEMENTS WON'T COPY
;INTO STRING SPACE -- WHICH IT MUST.
;N.B. TWO NONZERO BYTES MUST PRECEDE "BUFLNM".
; --- STORAGE FOR TEMPORARY THINGS ---:
TEMPPT: BLOCK 1 ;POINTER AT FIRST FREE TEMP DESCRIPTOR.
;INITIALIZED TO POINT TO TEMPST.
LASTPT: BLOCK 2 ;POINTER TO LAST-USED STRING TEMPORARY.
TEMPST: BLOCK STRSIZNUMTMP ;STORAGE FOR NUMTMP TEMP DESCRIPTORS.
INDEX1: BLOCK 2 ;INDEXES.
INDEX= INDEX1
INDEX2: BLOCK 2
RESHO: BLOCK 1 ;RESULT OF MULTIPLIER AND DIVIDER.
IFN ADDPRC,<
RESMOH: BLOCK 1> ;ONE MORE BYTE.
RESMO: BLOCK 1
RESLO: BLOCK 1
ADDEND= RESMO ;TEMPORARY USED BY "UMULT".
0 ;OVERFLOW FOR RES.
; --- POINTERS INTO DYNAMIC DATA STRUCTURES ---;
TXTTAB: BLOCK 2 ;POINTER TO BEGINNING OF TEXT.
;DOESN'T CHANGE AFTER BEING
;SETUP BY "INIT".
VARTAB: BLOCK 2 ;POINTER TO START OF SIMPLE
;VARIABLE SPACE.
;UPDATED WHENEVER THE SIZE OF THE
;PROGRAM CHANGES, SET TO [TXTTAB]
;BY "SCRATCH" ("NEW").
ARYTAB: BLOCK 2 ;POINTER TO BEGINNING OF ARRAY
;TABLE.
;INCREMENTED BY 6 WHENEVER
;A NEW SIMPLE VARIABLE IS FOUND, AND
;SET TO [VARTAB] BY "CLEARC".
STREND: BLOCK 2 ;END OF STORAGE IN USE.
;INCREASED WHENEVER A NEW ARRAY
;OR SIMPLE VARIABLE IS ENCOUNTERED.
;SET TO [VARTAB] BY "CLEARC".
FRETOP: BLOCK 2 ;TOP OF STRING FREE SPACE.
FRESPC: BLOCK 2 ;POINTER TO NEW STRING.
MEMSIZ: BLOCK 2 ;HIGHEST LOCATION IN MEMORY.
; --- LINE NUMBERS AND TEXTUAL POINTERS ---:
CURLIN: BLOCK 2 ;CURRENT LINE #.
;SET TO 0,255 FOR DIRECT STATEMENTS.
OLDLIN: BLOCK 2 ;OLD LINE NUMBER (SETUP BY ^C,"STOP"
;OR "END" IN A PROGRAM).
POKER= LINNUM ;SET UP LOCATION USED BY POKE.
;TEMPORARY FOR INPUT AND READ CODE
OLDTXT: BLOCK 2 ;OLD TEXT POINTER.
;POINTS AT STATEMENT TO BE EXEC'D NEXT.
DATLIN: BLOCK 2 ;DATA LINE # -- REMEMBER FOR ERRORS.
DATPTR: BLOCK 2 ;POINTER TO DATA. INITIALIZED TO POINT
;AT THE ZERO IN FRONT OF [TXTTAB]
;BY "RESTORE" WHICH IS CALLED BY "CLEARC".
;UPDATED BY EXECUTION OF A "READ".
INPPTR: BLOCK 2 ;THIS REMEMBERS WHERE INPUT IS COMING FROM.
; --- STUFF USED IN EVALUATIONS ---:
VARNAM: BLOCK 2 ;VARIABLE'S NAME IS STORED HERE.
VARPNT: BLOCK 2 ;POINTER TO VARIABLE IN MEMORY.
FDECPT= VARPNT ;POINTER INTO POWER OF TENS OF "FOUT".
FORPNT: BLOCK 2 ;A VARIABLE'S POINTER FOR "FOR" LOOPS
;AND "LET" STATEMENTS.
LSTPNT= FORPNT ;PNTR TO LIST STRING.
ANDMSK= FORPNT ;THE MASK USED BY WAIT FOR ANDING.
EORMSK= FORPNT+1 ;THE MASK FOR EORING IN WAIT.
OPPTR: BLOCK 2 ;POINTER TO CURRENT OP'S ENTRY IN "OPTAB".
VARTXT= OPPTR ;POINTER INTO LIST OF VARIABLES.
OPMASK: BLOCK 1 ;MASK CREATED BY CURRENT OPERATOR.
DOMASK=TANSGN ;MASK IN USE BY RELATION OPERATIONS.
DEFPNT: BLOCK 2 ;POINTER USED IN FUNCTION DEFINITION.
GRBPNT= DEFPNT ;ANOTHER USED IN GARBAGE COLLECTION.
DSCPNT: BLOCK 2 ;POINTER TO A STRING DESCRIPTOR.
IFN ADDPRC,<BLOCK 1> ;FOR TEMPF3.
FOUR6: EXP STRSIZ ;VARIABLE CONSTANT USED BY GARB COLLECT.
; --- ET CETERA ---:
JMPER: JMP 60000
SIZE= JMPER+1
OLDOV= JMPER+2 ;THE OLD OVERFLOW.
TEMPF3= DEFPNT ;A THIRD FAC TEMPORARY (4 BYTES).
TEMPF1:
IFN ADDPRC,<0> ;FOR TEMPF1S EXTRA BYTE.
HIGHDS: BLOCK 2 ;DESINATION OF HIGHEST ELEMENT IN BLT.
HIGHTR: BLOCK 2 ;SOURCE OF HIGHEST ELEMENT TO MOVE.
TEMPF2:
IFN ADDPRC,<0> ;FOR TEMPF2S EXTRA BYTE.
LOWDS: BLOCK 2 ;LOCATION OF LAST BYTE TRANSFERRED INTO.
LOWTR: BLOCK 2 ;LAST THING TO MOVE IN BLT.
ARYPNT= HIGHDS ;A POINTER USED IN ARRAY BUILDING.
GRBTOP= LOWTR ;A POINTER USED IN GARBAGE COLLECTION.
DECCNT= LOWDS ;NUMBER OF PLACES BEFORE DECIMAL POINT.
TENEXP= LOWDS+1 ;HAS A DPT BEEN INPUT?
DPTFLG= LOWTR ;BASE TEN EXPONENT.
EXPSGN= LOWTR+1 ;SIGN OF BASE TEN EXPONENT.
; --- THE FLOATING ACCUMULATOR ---:
FAC:
FACEXP: 0
FACHO: 0 ;MOST SIGNIFICANT BYTE OF MANTISSA.
IFN ADDPRC,<
FACMOH: 0> ;ONE MORE.
FACMO: 0 ;MIDDLE ORDER OF MANTISSA.
FACLO: 0 ;LEAST SIG BYTE OF MANTISSA.
FACSGN: 0 ;SIGN OF FAC (0 OR -1) WHEN UNPACKED.
SGNFLG: 0 ;SIGN OF FAC IS PRESERVED BERE BY "FIN".
DEGREE= SGNFLG ;A COUNT USED BY POLYNOMIALS.
DSCTMP= FAC ;THIS IS WHERE TEMP DESCS ARE BUILT.
INDICE= FACMO ;INDICE IS SET UP HERE BY "QINT".
BITS: 0 ;SOMETHING FOR "SHIFTR" TO USE.
; --- THE FLOATING ARGUMENT (UNPACKED) ---:
ARGEXP: 0
ARGHO: 0
IFN ADDPRC,<ARGMOH: 0>
ARGMO: 0
ARGLO: 0
ARGSGN: 0
ARISGN: 0 ;A SIGN REFLECTING THE RESULT.
FACOV: 0 ;OVERFLOW BYTE OF THE FAC.
STRNG1= ARISGN ;POINTER TO A STRING OR DESCRIPTOR.
FBUFPT: BLOCK 2 ;POINTER INTO FBUFFR USED BY FOUT.
BUFPTR= FBUFPT ;POINTER TO BUF USED BY "CRUNCH".
STRNG2= FBUFPT ;POINTER TO STRING OR DESC.
POLYPT= FBUFPT ;POINTER INTO POLYNOMIAL COEFFICIENTS.
CURTOL= FBUFPT ;ABSOLUTE LINEAR INDEX IS FORMED HERE.
PAGE
SUBTTL RAM CODE.
; THIS CODE GETS CHANGED THROUGHOUT EXECUTION.
; IT IS MADE TO BE FAST THIS WAY.
; ALSO, [X] AND [Y] ARE NOT DISTURBED
;
; "CHRGET" USING [TXTPTR] AS THE CURRENT TEXT PNTR
; FETCHES A NEW CHARACTER INTO ACCA AFTER INCREMENTING [TXTPTR]
; AND SETS CONDITION CODES ACCORDING TO WHAT'S IN ACCA.
; NOT C= NUMERIC ("0" THRU "9")
; Z= ":" OR END-OF-LINE (A NULL)
;
; [ACCA] = NEW CHAR.
; [TXTPTR]=[TXTPTR]+1
;
; THE FOLLOWING EXISTS IN ROM IF ROM EXISTS AND IS LOADED
; DOWN HERE BY INIT. OTHERWISE IT IS JUST LOADED INTO THIS
; RAM LIKE ALL THE REST OF RAM IS LOADED.
;
CHRGET: INC CHRGET+7 ;INCREMENT THE WHOLE TXTPTR.
BNE CHRGOT
INC CHRGET+8
CHRGOT: LDA 60000 ;A LOAD WITH AN EXT ADDR.
TXTPTR= CHRGOT+1
CMPI " " ;SKIP SPACES.
BEQ CHRGET
QNUM: CMPI ":" ;IS IT A ":"?
BCS CHRRTS ;IT IS .GE. ":"
SEC
SBCI "0" ;ALL CHARS .GT. "9" HAVE RET'D SO
SEC
SBCI 256-"0" ;SEE IF NUMERIC.
;TURN CARRY ON IF NUMERIC.
;ALSO, SETZ IF NULL.
CHRRTS: RTS ;RETURN TO CALLER.
RNDX: 128 ;LOADED OR FROM ROM.
79 ;THE INITIAL RANDOM NUMBER.
199
82
IFN ADDPRC,<89> ;ONE MORE BYTE.
ORG 255 ;PAGE 1 STUFF COMING UP.
LOFBUF: BLOCK 1 ;THE LOW FAC BUFFER. COPYABLE.
;--- PAGE ZERO/ONE BOUNDARY ---.
;MUST HAVE 13 CONTIGUOUS BYTES.
FBUFFR: BLOCK 3ADDPRC+13 ;BUFFER FOR "FOUT".
;ON PAGE 1 SO THAT STRING IS NOT COPIED.
;STACK IS LOCATED HERE. IE FROM THE END OF FBUFFR TO STKEND.
PAGE
SUBTTL DISPATCH TABLES, RESERVED WORDS, AND ERROR TEXTS.
ORG ROMLOC
STMDSP: ADR(END-1)
ADR(FOR-1)
ADR(NEXT-1)
ADR(DATA-1)
IFN EXTIO,<
ADR(INPUTN-1)>
ADR(INPUT-1)
ADR(DIM-1)
ADR(READ-1)
ADR(LET-1)
ADR(GOTO-1)
ADR(RUN-1)
ADR(IF-1)
ADR(RESTORE-1)
ADR(GOSUB-1)
ADR(RETURN-1)
ADR(REM-1)
ADR(STOP-1)
ADR(ONGOTO-1)
IFN NULCMD,<
ADR(NULL-1)>
ADR(FNWAIT-1)
IFN DISKO,<
IFE REALIO-3,<
ADR(CQLOAD-1)
ADR(CQSAVE-1)
ADR(CQVERF-1)>
IFN REALIO,<
IFN REALIO-2,<
IFN REALIO-3,<
IFN REALIO-5,<
ADR(LOAD-1)
ADR(SAVE-1)>>>>
IFN REALIO-1,<
IFN REALIO-3,<
IFN REALIO-4,<
ADR(511) ;ADDRESS OF LOAD
ADR(511)>>>> ;ADDRESS OF SAVE
ADR(DEF-1)
ADR(POKE-1)
IFN EXTIO,<
ADR(PRINTN-1)>
ADR(PRINT-1)
ADR(CONT-1)
IFE REALIO,<
ADR(DDT-1)>
ADR(LIST-1)
ADR(CLEAR-1)
IFN EXTIO,<
ADR(CMD-1)
ADR(CQSYS-1)
ADR(CQOPEN-1)
ADR(CQCLOS-1)>
IFN GETCMD,<
ADR(GET-1)> ;FILL W/ GET ADDR.
ADR(SCRATH-1)
FUNDSP: ADR(SGN)
ADR(INT)
ADR(ABS)
IFE ROMSW,<
USRLOC: ADR(FCERR)> ;INITIALLY NO USER ROUTINE.
IFN ROMSW,<
USRLOC: ADR(USRPOK)>
ADR(FRE)
ADR(POS)
ADR(SQR)
ADR(RND)
ADR(LOG)
ADR(EXP)
IFN KIMROM,<
REPEAT 4,<
ADR(FCERR)>>
IFE KIMROM,<
COSFIX: ADR(COS)
SINFIX: ADR(SIN)
TANFIX: ADR(TAN)
ATNFIX: ADR(ATN)>
ADR(PEEK)
ADR(LEN)
ADR(STR)
ADR(VAL)
ADR(ASC)
ADR(CHR)
ADR(LEFT)
ADR(RIGHT)
ADR(MID)
OPTAB: 121
ADR(FADDT-1)
121
ADR(FSUBT-1)
123
ADR(FMULTT-1)
123
ADR(FDIVT-1)
127
ADR(FPWRT-1)
80
ADR(ANDOP-1)
70
ADR(OROP-1)
NEGTAB: 125
ADR(NEGOP-1)
NOTTAB: 90
ADR(NOTOP-1)
PTDORL: 100 ;PRECEDENCE.
ADR (DOREL-1) ;OPERATOR ADDRESS.
;
; TOKENS FOR RESERVED WORDS ALWAYS HAVE THE MOST
; SIGNIFICANT BIT ON.
; THE LIST OF RESERVED WORDS:
;
Q=128-1
DEFINE DCI(A),<Q=Q+1
DC(A)>
RESLST: DCI"END"
ENDTK==Q
DCI"FOR"
FORTK==Q
DCI"NEXT"
DCI"DATA"
DATATK==Q
IFN EXTIO,<
DCI"INPUT#">
DCI"INPUT"
DCI"DIM"
DCI"READ"
DCI"LET"
DCI"GOTO"
GOTOTK==Q
DCI"RUN"
DCI"IF"
DCI"RESTORE"
DCI"GOSUB"
GOSUTK=Q
DCI"RETURN"
DCI"REM"
REMTK=Q
DCI"STOP"
DCI"ON"
IFN NULCMD,<
DCI"NULL">
DCI"WAIT"
IFN DISKO,<
DCI"LOAD"
DCI"SAVE"
IFE REALIO-3,<
DCI"VERIFY">>
DCI"DEF"
DCI"POKE"
IFN EXTIO,<
DCI"PRINT#">
DCI"PRINT"
PRINTK==Q
DCI"CONT"
IFE REALIO,<
DCI"DDT">
DCI"LIST"
IFN REALIO-3,<
DCI"CLEAR">
IFE REALIO-3,<
DCI"CLR">
IFN EXTIO,<
DCI"CMD"
DCI"SYS"
DCI"OPEN"
DCI"CLOSE">
IFN GETCMD,<
DCI"GET">
DCI"NEW"
SCRATK=Q
; END OF COMMAND LIST.
"T"
"A"
"B"
"("+128
Q=Q+1
TABTK=Q
DCI"TO"
TOTK==Q
DCI"FN"
FNTK==Q
"S"
"P"
"C"
"("+128 ;MACRO DOESNT LIKE ('S IN ARGUMENTS.
Q=Q+1
SPCTK==Q
DCI"THEN"
THENTK=Q
DCI"NOT"
NOTTK==Q
DCI"STEP"
STEPTK=Q
DCI"+"
PLUSTK=Q
DCI"-"
MINUTK=Q
DCI""
DCI"/"
DCI"^"
DCI"AND"
DCI"OR"
190 ;A GREATER THAN SIGN
Q=Q+1
GREATK=Q
DCI"="
EQULTK=Q
188
Q=Q+1 ;A LESS THAN SIGN
LESSTK=Q
;
; NOTE DANGER OF ONE RESERVED WORD BEING A PART
; OF ANOTHER:
; IE . . IF 2 GREATER THAN F OR T=5 THEN...
; WILL NOT WORK!!! SINCE "FOR" WILL BE CRUNCHED!!
; IN ANY CASE MAKE SURE THE SMALLER WORD APPEARS
; SECOND IN THE RESERVED WORD TABLE ("INP" AND "INPUT")
; ANOTHER EXAMPLE: IF T OR Q THEN ... "TO" IS CRUNCHED
;
DCI"SGN"
ONEFUN=Q
DCI"INT"
DCI"ABS"
DCI"USR"
DCI"FRE"
DCI"POS"
DCI"SQR"
DCI"RND"
DCI"LOG"
DCI"EXP"
DCI"COS"
DCI"SIN"
DCI"TAN"
DCI"ATN"
DCI"PEEK"
DCI"LEN"
DCI"STR$"
DCI"VAL"
DCI"ASC"
DCI"CHR$"
LASNUM==Q ;NUMBER OF LAST FUNCTION
;THAT TAKES ONE ARG
DCI"LEFT$"
DCI"RIGHT$"
DCI"MID$"
DCI"GO"
GOTK==Q
0 ;MARKS END OF RESERVED WORD LIST
IFE LNGERR,<
Q=0-2
DEFINE DCE(X),<Q=Q+2
DC(X)>
ERRTAB: DCE"NF"
ERRNF==Q ;NEXT WITHOUT FOR.
DCE"SN"
ERRSN==Q ;SYNTAX
DCE"RG"
ERRRG==Q ;RETURN WITHOUT GOSUB.
DCE"OD"
ERROD==Q ;OUT OF DATA.
DCE"FC"
ERRFC==Q ;ILLEGAL QUANTITY.
DCE"OV"
ERROV==Q ;OVERFLOW.
DCE"OM"
ERROM==Q ;OUT OF MEMORY.
DCE"US"
ERRUS==Q ;UNDEFINED STATEMENT.
DCE"BS"
ERRBS==Q ;BAD SUBSCRIPT.
DCE"DD"
ERRDD==Q ;REDIMENSIONED ARRAY.
DCE"/0"
ERRDV0==Q ;DIVISION BY ZERO.
DCE"ID"
ERRID==Q ;ILLEGAL DIRECT.
DCE"TM"
ERRTM==Q ;TYPE MISMATCH.
DCE"LS"
ERRLS==Q ;STRING TOO LONG.
IFN EXTIO,<
DCE"FD" ;FILE DATA.
ERRBD==Q>
DCE"ST"
ERRST==Q ;STRING FORMULA TOO COMPLEX.
DCE"CN"
ERRCN==Q ;CAN'T CONTINUE.
DCE"UF"
ERRUF==Q> ;UNDEFINED FUNCTION.
IFN LNGERR,<
Q=0
; NOTE: THIS ERROR COUNT TECHNIQUE WILL NOT WORK IF THERE ARE MORE
; THAN 256 CHARACTERS OF ERROR MESSAGES
ERRTAB: DC"NEXT WITHOUT FOR"
ERRNF==Q
Q=Q+16
DC"SYNTAX"
ERRSN==Q
Q=Q+6
DC"RETURN WITHOUT GOSUB"
ERRRG==Q
Q=Q+20
DC"OUT OF DATA"
ERROD==Q
Q=Q+11
DC"ILLEGAL QUANTITY"
ERRFC==Q
Q=Q+16
DC"OVERFLOW"
ERROV==Q
Q=Q+8
DC"OUT OF MEMORY"
ERROM==Q
Q=Q+13
DC"UNDEF'D STATEMENT"
ERRUS==Q
Q=Q+17
DC"BAD SUBSCRIPT"
ERRBS==Q
Q=Q+13
DC"REDIM'D ARRAY"
ERRDD==Q
Q=Q+13
DC"DIVISION BY ZERO"
ERRDV0==Q
Q=Q+16
DC"ILLEGAL DIRECT"
ERRID==Q
Q=Q+14
DC"TYPE MISMATCH"
ERRTM==Q
Q=Q+13
DC"STRING TOO LONG"
ERRLS==Q
Q=Q+15
IFN EXTIO,<
DC"FILE DATA"
ERRBD==Q
Q=Q+9>
DC"FORMULA TOO COMPLEX"
ERRST==Q
Q=Q+19
DC"CAN'T CONTINUE"
ERRCN==Q
Q=Q+14
DC"UNDEF'D FUNCTION"
ERRUF==Q>
;
; NEEDED FOR MESSAGES IN ALL VERSIONS.
;
ERR: DT" ERROR"
0
INTXT: DT" IN "
0
REDDY: ACRLF
IFE REALIO-3,<
DT"READY.">
IFN REALIO-3,<
DT"OK">
ACRLF
0
BRKTXT: ACRLF
DT"BREAK"
0
PAGE
SUBTTL GENERAL STORAGE MANAGEMENT ROUTINES.
;
; FIND A "FOR" ENTRY ON THE STACK VIA "VARPNT".
;
FORSIZ==2ADDPRC+16
FNDFOR: TSX ;LOAD XREG WITH STK PNTR.
REPEAT 4,<INX> ;IGNORE ADR(NEWSTT) AND RTS ADDR.
FFLOOP: LDA 257,X ;GET STACK ENTRY.
CMPI FORTK ;IS IT A "FOR" TOKEN?
BNE FFRTS ;NO, NO "FOR" LOOPS WITH THIS PNTR.
LDA FORPNT+1 ;GET HIGH.
BNE CMPFOR
LDA 258,X ;PNTR IS ZERO, SO ASSUME THIS ONE.
STA FORPNT
LDA 259,X
STA FORPNT+1
CMPFOR: CMP 259,X
BNE ADDFRS ;NOT THIS ONE.
LDA FORPNT ;GET DOWN.
CMP 258,X
BEQ FFRTS ;WE GOT IT! WE GOT IT!
ADDFRS: TXA
CLC ;ADD 16 TO X.
ADCI FORSIZ
TAX ;RESULT BACK INTO X.
BNE FFLOOP
FFRTS: RTS ;RETURN TO CALLER.
;
; THIS IS THE BLOCK TRANSFER ROUTINE.
; IT MAKES SPACE BY SHOVING EVERYTHING FORWARD.
;
; ON ENTRY:
; [Y,A]=[HIGHDS] (FOR REASON).
; [HIGHDS]= DESTINATION OF [HIGH ADDRESS].
; [LOWTR]= LOWEST ADDR TO BE TRANSFERRED.
; [HIGHTR]= HIGHEST ADDR TO BE TRANSFERRED.
;
; A CHECK IS MADE TO ASCERTAIN THAT A REASONABLE
; AMOUNT OF SPACE REMAINS BETWEEN THE BOTTOM
; OF THE STRINGS AND THE HIGHEST LOCATION TRANSFERRED INTO.
;
; ON EXIT:
; [LOWTR] ARE UNCHANGED.
; [HIGHTR]=[LOWTR]-200 OCTAL.
; [HIGHDS]=LOWEST ADDR TRANSFERRED INTO MINUS 200 OCTAL.
;
BLTU: JSR REASON ;ASCERTAIN THAT STRING SPACE WON'T
;BE OVERRUN.
STWD STREND
BLTUC: SEC ;PREPARE TO SUBTRACT.
LDA HIGHTR
SBC LOWTR ;COMPUTE NUMBER OF THINGS TO MOVE.
STA INDEX ;SAVE FOR LATER.
TAY
LDA HIGHTR+1
SBC LOWTR+1
TAX ;PUT IT IN A COUNTER REGISTER.
INX ;SO THAT COUNTER ALGORITHM WORKS.
TYA ;SEE IF LOW PART OF COUNT IS ZERO.
BEQ DECBLT ;YES, GO START MOVING BLOCKS.
LDA HIGHTR ;NO, MUST MODIFY BASE ADDR.
SEC
SBC INDEX ;BORROW IS OFF SINCE [HIGHTR].GT.[LOWTR].
STA HIGHTR ;SAVE MODIFIED BASE ADDR.
BCS BLT1 ;IF NO BORROW, GO SHOVE IT.
DEC HIGHTR+1 ;BORROW IMPLIES SUB 1 FROM HIGH ORDER.
SEC
BLT1: LDA HIGHDS ;MOD BASE OF DEST ADDR.
SBC INDEX
STA HIGHDS
BCS MOREN1 ;NO BORROW.
DEC HIGHDS+1 ;DECREMENT HIGH ORDER BYTE.
BCC MOREN1 ;ALWAYS SKIP.
BLTLP: LDADY HIGHTR ;FETCH BYTE TO MOVE
STADY HIGHDS ;MOVE IT IN, MOVE IT OUT.
MOREN1: DEY
BNE BLTLP
LDADY HIGHTR ;MOVE LAST OF THE BLOCK.
STADY HIGHDS
DECBLT: DEC HIGHTR+1
DEC HIGHDS+1 ;START ON NEW BLOCKS.
DEX
BNE MOREN1
RTS ;RETURN TO CALLER.
;
; THIS ROUTINE IS USED TO ASCERTAIN THAT A GIVEN
; NUMBER OF LOCS REMAIN AVAILABLE FOR THE STACK.
; THE CALL IS:
; LDAI NUMBER OF 2-BYTE ENTRIES NEEDED.
; JSR GETSTK
;
; THIS ROUTINE MUST BE CALLED BY ANY ROUTINE WHICH PUTS
; AN ARBITRARY AMOUNT OF STUFF ON THE STACK,
; I.E., ANY RECURSIVE ROUTINE LIKE "FRMEVL".
; IT IS ALSO CALLED BY ROUTINES SUCH AS "GOSUB" AND "FOR"
; WHICH MAKE PERMANENT ENTRIES ON THE STACK.
;
; ROUTINES WHICH MERELY USE AND FREE UP THE GUARANTEED
; NUMLEV LOCATIONS NEED NOT CALL THIS.
;
;
; ON EXIT:
; [A] AND [X] HAVE BEEN MODIFIED.
;
GETSTK: ASL A, ;MULT [A] BY 2. NB, CLEARS C BIT.
ADCI 2NUMLEV+<3ADDPRC>+13 ;MAKE SURE 2NUMLEV+13 LOCS
;(13 BECAUSE OF FBUFFR)
BCS OMERR ;WILL REMAIN IN STACK.
STA INDEX
TSX ;GET STACKED.
CPX INDEX ;COMPARE.
BCC OMERR ;IF STACK.LE.INDEX1, OM.
RTS
;
; [Y,A] IS A CERTAIN ADDRESS. "REASON" MAKES SURE
; IT IS LESS THAN [FRETOP].
;
REASON: CPY FRETOP+1
BCC REARTS
BNE TRYMOR ;GO GARB COLLECT.
CMP FRETOP
BCC REARTS
TRYMOR: PHA
LDXI 8+ADDPRC ;IF TEMPF2 HAS ZERO IN BETWEEN.
TYA
REASAV: PHA
LDA HIGHDS-1,X ;SAVE HIGHDS ON STACK.
DEX
BPL REASAV ;PUT 8 OF THEM ON STK.
JSR GARBA2 ;GO GARB COLLECT.
LDXI 256-8-ADDPRC
REASTO: PLA
STA HIGHDS+8+ADDPRC,X ;RESTORE AFTER GARB COLLECT.
INX
BMI REASTO
PLA
TAY
PLA ;RESTORE A AND Y.
CPY FRETOP+1 ;COMPARE HIGHS
BCC REARTS
BNE OMERR ;HIGHER IS BAD.
CMP FRETOP ;AND THE LOWS.
BCS OMERR
REARTS: RTS
PAGE
SUBTTL ERROR HANDLER, READY, TERMINAL INPUT, COMPACTIFY, NEW, REINIT.
OMERR: LDXI ERROM
ERROR:
IFN REALIO,<
LSR CNTWFL> ;FORCE OUTPUT.
IFN EXTIO,<
LDA CHANNL ;CLOSE NON-TERMINAL CHANNEL.
BEQ ERRCRD
JSR CQCCHN ;CLOSE IT.
LDAI 0
STA CHANNL>
ERRCRD: JSR CRDO ;OUTPUT CRLF.
JSR OUTQST ;PRINT A QUESTION MARK
IFE LNGERR,<
LDA ERRTAB,X, ;GET FIRST CHR OF ERR MSG.
JSR OUTDO ;OUTPUT IT.
LDA ERRTAB+1,X, ;GET SECOND CHR.
JSR OUTDO> ;OUTPUT IT.
IFN LNGERR,<
GETERR: LDA ERRTAB,X
PHA
ANDI 127 ;GET RID OF HIGH BIT.
JSR OUTDO ;OUTPUT IT.
INX
PLA ;LAST CHAR OF MESSAGE?
BPL GETERR> ;NO. GO GET NEXT AND OUTPUT IT.
TYPERR: JSR STKINI ;RESET THE STACK AND FLAGS.
LDWDI ERR ;GET PNTR TO " ERROR".
ERRFIN: JSR STROUT ;OUTPUT IT.
LDY CURLIN+1
INY ;WAS NUMBER 64000?
BEQ READY ;YES, DON'T TYPE LINE NUMBER.
JSR INPRT
READY:
IFN REALIO,<
LSR CNTWFL> ;TURN OUTPUT BACK ON IF SUPRESSED
LDWDI REDDY ;SAY "OK".
IFN REALIO-3,<
JSR RDYJSR> ;OR GO TO INIT IF INIT ERROR.
IFE REALIO-3,<
JSR STROUT> ;NO INIT ERRORS POSSIBLE.
MAIN: JSR INLIN ;GET A LINE FROM TERMINAL.
STXY TXTPTR
JSR CHRGET
TAX ;SET ZERO FLAG BASED ON [A]
;THIS DISTINGUISHES ":" AND 0
BEQ MAIN ;IF BLANK LINE, GET ANOTHER.
LDXI 255 ;SET DIRECT LINE NUMBER.
STX CURLIN+1
BCC MAIN1 ;IS A LINE NUMBER. NOT DIRECT.
JSR CRUNCH ;COMPACTIFY.
JMP GONE ;EXECUTE IT.
MAIN1: JSR LINGET ;READ LINE NUMBER INTO "LINNUM".
JSR CRUNCH
STY COUNT ;RETAIN CHARACTER COUNT.
JSR FNDLIN
BCC NODEL ;NO MATCH, SO DON'T DELETE.
LDYI 1
LDADY LOWTR
STA INDEX1+1
LDA VARTAB
STA INDEX1
LDA LOWTR+1 ;SET TRANSFER TO.
STA INDEX2+1
LDA LOWTR
DEY
SBCDY LOWTR ;COMPUTE NEGATIVE LENGTH.
CLC
ADC VARTAB ;COMPUTE NEW VARTAB.
STA VARTAB
STA INDEX2 ;SET LOW OF TRANS TO.
LDA VARTAB+1
ADCI 255
STA VARTAB+1 ;COMPUTE HIGH OF VARTAB.
SBC LOWTR+1 ;COMPUTE NUMBER OF BLOCKS TO MOVE.
TAX
SEC
LDA LOWTR
SBC VARTAB ;COMPUTE OFFSET.
TAY
BCS QDECT1 ;IF VARTAB.LE.LOWTR,
INX ;DECR DUE TO CARRY, AND
DEC INDEX2+1 ;DECREMENT STORE SO CARRY WORKS.
QDECT1: CLC
ADC INDEX1
BCC MLOOP
DEC INDEX1+1
CLC ;FOR LATER ADCQ
MLOOP: LDADY INDEX1
STADY INDEX2
INY
BNE MLOOP ;BLOCK DONE?
INC INDEX1+1
INC INDEX2+1
DEX
BNE MLOOP ;DO ANOTHER BLOCK. ALWAYS.
NODEL: JSR RUNC ;RESET ALL VARIABLE INFO SO GARBAGE
;COLLECTION CAUSED BY REASON WILL WORK
JSR LNKPRG ;FIX UP THE LINKS
LDA BUF ;SEE IF ANYTHNG THERE
BEQ MAIN
CLC
LDA VARTAB
STA HIGHTR ;SETUP HIGHTR.
ADC COUNT ;ADD LENGTH OF LINE TO INSERT.
STA HIGHDS ;THIS GIVES DEST ADDR.
LDY VARTAB+1
STY HIGHTR+1 ;SAME FOR HIGH ORDERS.
BCC NODELC
INY
NODELC: STY HIGHDS+1
JSR BLTU
IFN BUFPAG,<
LDWD LINNUM ;POSITION THE BINARY LINE NUMBER
STWD BUF-2> ;IN FRONT OF BUF
LDWD STREND
STWD VARTAB
LDY COUNT
DEY
STOLOP: LDA BUF-4,Y
STADY LOWTR
DEY
BPL STOLOP
FINI: JSR RUNC ;DO CLEAR & SET UP STACK.
;AND SET [TXTPTR] TO [TXTTAB]-1.
JSR LNKPRG ;FIX UP PROGRAM LINKS
JMP MAIN
LNKPRG: LDWD TXTTAB ;SET [INDEX] TO [TXTTAB].
STWD INDEX
CLC
;
; CHEAD GOES THROUGH PROGRAM STORAGE AND FIXES
; UP ALL THE LINKS. THE END OF EACH LINE IS FOUND
; BY SEARCHING FOR THE ZERO AT THE END.
; THE DOUBLE ZERO LINK IS USED TO DETECT THE END OF THE PROGRAM.
;
CHEAD: LDYI 1
LDADY INDEX ;ARRIVED AT DOUBLE ZEROES?
BEQ LNKRTS
LDYI 4
CZLOOP: INY ;THERE IS AT LEAST ONE BYTE.
LDADY INDEX
BNE CZLOOP ;NO, CONTINUE SEARCHING.
INY ;GO ONE BEYOND.
TYA
ADC INDEX
TAX
LDYI 0
STADY INDEX
LDA INDEX+1
ADCI 0
INY
STADY INDEX
STX INDEX
STA INDEX+1
BCCA CHEAD ;ALWAYS BRANCHES.
LNKRTS: RTS
;
; THIS IS THE LINE INPUT ROUTINE.
; IT READS CHARACTERS INTO BUF USING BACKARROW (UNDERSCORE, OR
; SHIFT O) AS THE DELETE CHARACTER AND @ AS THE
; LINE DELETE CHARACTER. IF MORE THAN BUFLEN CHARACTERS
; ARE TYPED, NO ECHOING IS DONE UNTIL A BACKARROW OR @ OR CR
; IS TYPED. CONTROL-G WILL BE TYPED FOR EACH EXTRA CHARACTER.
; THE ROUTINE IS ENTERED AT INLIN.
;
IFE REALIO-4,<
INLIN: LDXI 128 ;NO PROMPT CHARACTER
STX CQPRMP
JSR CQINLN ;GET A LINE ONTO PAGE 2
CPXI BUFLEN-1
BCS GDBUFS ;NOT TOO MANY CHARACTERS
LDXI BUFLEN-1
GDBUFS: LDAI 0 ;PUT A ZERO AT THE END
STA BUF,X
TXA
BEQ NOCHR
LOPBHT: LDA BUF-1,X
ANDI 127
STA BUF-1,X
DEX
BNE LOPBHT
NOCHR: LDAI 0
LDXYI <BUF-1> ;POINT AT THE BEGINNING
RTS>
IFN REALIO-4,<
IFN REALIO-3,<
LINLIN: IFE REALIO-2,<
JSR OUTDO> ;ECHO IT.
DEX ;BACKARROW SO BACKUP PNTR AND
BPL INLINC ;GET ANOTHER IF COUNT IS POSITIVE.
INLINN: IFE REALIO-2,<
JSR OUTDO> ;PRINT THE @ OR A SECOND BACKARROW
;IF THERE WERE TOO MANY.
JSR CRDO>
INLIN: LDXI 0
INLINC: JSR INCHR ;GET A CHARACTER.
IFN REALIO-3,<
CMPI 7 ;IS IT BOB ALBRECHT RINGING THE BELL
;FOR SCHOOL KIDS?
BEQ GOODCH>
CMPI 13 ;CARRIAGE RETURN?
BEQ FININ1 ;YES, FINISH UP.
IFN REALIO-3,<
CMPI 32 ;CHECK FOR FUNNY CHARACTERS.
BCC INLINC
CMPI 125 ;IS IT TILDA OR DELETE?
BCS INLINC ;BIG BAD ONES TOO.
CMPI "@" ;LINE DELETE?
BEQ INLINN ;YES.
CMPI "_" ;CHARACTER DELETE?
BEQ LINLIN> ;YES.
GOODCH:
IFN REALIO-3,<
CPXI BUFLEN-1 ;LEAVE ROOM FOR NULL.
;COMMO ASSURES US NEVER MORE THAN BUFLEN.
BCS OUTBEL>
STA BUF,X
INX
IFE REALIO-2,<SKIP2>
IFN REALIO-2,<BNE INLINC>
IFN REALIO-3,<
OUTBEL: LDAI 7
IFN REALIO,<
JSR OUTDO> ;ECHO IT.
BNE INLINC> ;CYCLE ALWAYS.
FININ1: JMP FININL> ;GO TO FININL FAR, FAR AWAY.
INCHR:
IFE REALIO-3,<
JSR CQINCH> ;FOR COMMODORE.
IFE REALIO-2,<
INCHRL: LDA ^O176000
REPEAT 4,<NOP>
LSR A,
BCC INCHRL
LDA ^O176001 ;GET THE CHARACTER.
REPEAT 4,<NOP>
ANDI 127>
IFE REALIO-1,<
JSR ^O17132> ;1E5A FOR MOS TECH.
IFE REALIO-4,<
JSR CQINCH ;FD0C FOR APPLE COMPUTER.
ANDI 127>
IFE REALIO,<
TJSR INSIM##> ;GET A CHARACTER FROM SIMULATOR
IFN REALIO,<
IFN EXTIO,<
LDY CHANNL ;CNT-O HAS NO EFFECT IF NOT FROM TERM.
BNE INCRTS>
CMPI CONTW ;SUPPRESS OUTPUT CHARACTER (^W).
BNE INCRTS ;NO, RETURN.
PHA
COM CNTWFL ;COMPLEMENT ITS STATE.
PLA>
INCRTS: RTS ;END OF INCHR.
;
; ALL "RESERVED" WORDS ARE TRANSLATED INTO SINGLE
; BYTES WITH THE MSB ON. THIS SAVES SPACE AND TIME
; BY ALLOWING FOR TABLE DISPATCH DURING EXECUTION.
; THEREFORE ALL STATEMENTS APPEAR TOGETHER IN THE
; RESERVED WORD LIST IN THE SAME ORDER THEY
; APPEAR IN STMDSP.
;
BUFOFS=0 ;THE AMOUNT TO OFFSET THE LOW BYTE
;OF THE TEXT POINTER TO GET TO BUF
;AFTER TXTPTR HAS BEE
