Introduction fo Byte-Oriented File Input/Output Routines
Byte-Oriented Input and Output File Open
Byte-Oriented Input and Output File Close
Byte-Oriented Input and Output
Error Return Codes
:Byte-Oriented File Input/Output Routines
    Th� followin� documentatio� cover� th� serie� o� byte-�
oriente� fil� input/outpu� routine� i� SYSLIB��  Thes� routine� �
allo� th� use� t� sequentiall� rea� fro� (GET� an� writ� t� (PUT� �
� fil� o� � byte-for-byt� basis��  Hence�� thes� routine� provid� �
a� exceptionall� simpl� metho� fo� handlin� inpu� fro� an� outpu� �
t� � file.
    � typica� progra� whic� employ� thes� routine� mus� ope� th� �
require� file� befor� doin� an� processing� mus� the� perfor� th� �
processin� o� th� opene� files�� an� mus� the� clos� th� file� �
whe� th� processin� i� complet� (closin� th� file� i� optiona� �
fo� inpu� file� an� mandator� fo� outpu� files).
    SYSLI� provide� fou� set� o� routine� fo� byte-oriente� fil� �
inpu� an� output�  Thes� routine� ar� --

Input Open     Output Open     GET    PUT   Input Close  Output Close
----------     -----------     ---    --�   -----------  ------------
FI0$OPEN       FO0$OPEN      F0$GET F0$PUT  FI0$CLOSE    FO0$CLOSE
FI1$OPEN       FO1$OPEN      F1$GET F1$PUT  FI1$CLOSE    FO1$CLOSE
FI2$OPEN       FO2$OPEN      F2$GET F2$PUT  FI2$CLOSE    FO2$CLOSE
FI3$OPEN       FO3$OPEN      F3$GET F3$PUT  FI3$CLOSE    FO3$CLOSE

    Thi� syste� allow� th� use� t� hav� u� t� �� file� ope� �
simultaneousl� -- fou� ar� ope� fo� inpu� usin� GE� an� fou� ar� �
ope� fo� outpu� usin� PUT��  Fo� example�� th� followin� i� � �
sampl� cod� sectio� usin� thes� routine� fo� tw� files:


         EXT  FI0$OPEN   ; DECLARE LIBRARY REFERENCES
         EXT  FO0$OPEN
         EXT  FI0$CLOSE
         EXT  FO0$CLOSE
         EXT  F0$GET
         EXT  F0$PUT
         ...
         LXI  D,FCBI    ; PT TO FCB OF INPUT FILE
         CALL FI0$OPEN
         LXI  D,FCBO    ; PT TO FCB OF OUTPUT FILE
         CALL FO0$OPEN
         ...
         [body containing CALL F0$GET and CALL F0$PUT where required]
         ...
         CALL FI0$CLOSE  ; CLOSE FILE
         CALL FO0$CLOSE
         ...
         END
     Not� tha� onl� th� routine� t� b� use� ar� reference� i� th� �
EX� statements��  I� yo� d� no� nee� � particula� routine� d� no� �
referenc� it��  No� referencin� a� unneede� routin� generall� �
save� th� overhea� memor� spac� o� loadin� i� fro� th� library.
    Eac� se� o� INPU� OPEN�� INPU� CLOSE�� OUTPUԠ OPEN�� OUTPU� �
CLOSE�� GET� an� PU� routine� i� containe� i� on� librar� module� �
s� referencin� an� o� thes� routine� cause� th� entir� modul� t� �
b� loaded�� an� al� th� routine� ar� accessabl� t� th� use� �
(provide� the� ar� mentione� i� th� externa� definitions� withou� �
an��� additiona� memor��� overhead���  Specifically��� FI0$OPEN� �
FI0$CLOSE�� FO0$OPEN� FO0$CLOSE� F0$GET� an� F0$PU� ar� containe� �
i� on� module�� an� referenc� t� an� o� thes� routine� load� th� �
entir� module� th� sam� i� tru� fo� th� othe� set� o� routines.
    Th� CLOS� routin� fo� outpu� (FOn$CLOSE� i� ALWAY� required� �
i� fill� th� res� o� th� curren� bloc� wit� Ctrl-� followe� b� �
<NULL�� byte� an� properl� close� file��  Th� CLOSŠ routin� fo� �
inpu� (FIn$CLOSE� i� require� ONL� I� yo� ar� goin� t� late� ope� �
anothe� fil� fo� inpu� usin� th� correspondin� OPEΠ routin� �
(FIn$OPEN)��  FIn$CLOSŠ onl� serve� t� rese� th� OPE� fla� (use� �
t� GE� t� ascertai� tha� th� fil� ha� bee� properl� opened).
:FI$OPEN and FO$OPEN, et al -- Byte-Oriented Input and Output File Open
    Routine Names:  FI0$OPEN, FI1$OPEN, FI2$OPEN, FI3$OPEN
    Function�
         Ope� th� fil� whos� FC� i� pointe� t� b� D� fo� inpu� �
(us� wit� F$GET)��  FIn$OPEΠ initialize� th� FC  fields�� s� �
further initialization is not necessary.
    Inputs:  DE = ptr to FCB of file to open
    Outputs:  Z Flag is Error Indicator, A is Error Code
    Registers Affected:  PSW
    SYSLIB Routines Called:  Internal
    Special Error Conditions:  See Section on Error Codes

    Routine Names:  FO0$OPEN, FO1$OPEN, FO2$OPEN, FO3$OPEN
    Function�
         Ope� th� fil� whos� FC� i� pointe� t� b� D� fo� outpu� �
(us� wit� F$PUT)��  FOn$OPE� initialize� th� FC  fields�� s� �
furthe� initializatio� i� no� necessary��  I� als� create� th� �
indicated file if it does not already exist.
    Inputs:  DE = ptr to FCB of file to open
    Outputs:  Z Flag is Error Indicator, A is Error Code
    Registers Affected:  PSW
    SYSLIB Routines Called:  Internal
    Special Error Conditions:  See Section on Error Codes
:FI$CLOSE and FO$CLOSE, et al -- Byte-Oriented Input and Output File Close
    Routine Names:  FI0$CLOSE, FI1$CLOSE, FI2$CLOSE, FI3$CLOSE
    Function�
         Clos� th� fil� previousl� opene� b� th� correspondin� �
FI$OPEΠ routine��  Us� o� thes� routine� i� optiona� i� th� �
anothe� fil� wil� no� b� opene� late� i� th� progra� b�� th� �
correspondin� FI$OPE� routine.
    Inputs:  -None-
    Outputs:  Z Flag is Error Indicator, A is Error Code
    Registers Affected:  PSW
    SYSLIB Routines Called:  Internal
    Specia� Erro� Conditions:  See Section on Error Codes

    Routine Names:  FO0$CLOSE, FO1$CLOSE, FO2$CLOSE, FO3$CLOSE
    Function�
         Clos� th� fil� previousl� opene� b� th� correspondin� �
FO$OPE� routine�  Us� o� thes� routine� i� MANDATOR� afte� outpu� �
t� th� fil� (usin� th� correspondin� F$PU� routine� i� complete.
    Inputs:  -None-
    Outputs:  Z Flag is Error Indicator, A is Error Code
    Registers Affected:  -None-
    SYSLIB Routines Called:  Internal
    Specia� Erro� Conditions:  See Section on Error Codes
:F$GET and F$PUT, et al -- Byte-Oriented Input and Output
    Routine Names:  F0$GET, F1$GET, F2$GET, F3$GET
    Function�
         Ge� th� nex� byt� i� sequenc� fro� th� fil� previousl� �
opene� b� th� correspondin� FI$OPE� routine�  Byt� i� returne� i� �
Registe� A.
    Inputs:  -None-
    Outputs:  A = Next byte from file if no error
              If Error, NZ and A = Error Code
    Registers Affected:  PSW
    SYSLIB Routines Called:  Internal
    Specia� Erro� Conditions:  See Section on Error Codes

    Routine Names:  F0$PUT, F1$PUT, F2$PUT, F3$PUT
    Function�
         Pu� th� byt� i� Registe� � ont� th� en� o� th� fil� �
previousl� opene� b� th� correspondin� FO$OPE� routine.
    Inputs:  A = Byte to PUT
    Outputs:  Z Flag is Error Indicator, A is Error Code
    Registers Affected:  PSW
    SYSLIB Routines Called:  Internal
    Specia� Erro� Conditions�  See Section on Error Codes
:Error Return Codes

    Fo� eac� o� th� routine� i� thi� se� o� byte-oriente� fil� �
I/� routines� th� Zer� Fla� an� th� � Registe� pla� � ke� rol� i� �
indicating the error conditions of the routines.

    I� th� Zer� Fla� i� Se� (Z� afte� � routin� ha� bee� �
executed�� the� thi� indicate� tha� n� erro� ha� occurred�  Th� � �
Registe� i� eithe� unaffecte� (i� mos� cases�� o� contain� � �
returned value (if so indicated, as in Fn$GET routines).

    I� th� Zer� Fla� i� Clea� (NZ� afte� � routin� ha� bee� �
executed�� the� thi� indicate� tha� a� erro� ha� occurred�  Th� � �
Registe� no�� contain� th� Erro� Code��  Th� followin� tabl� �
summarize� th� Erro� Code� whic� ma� b� returne� i� th� � �
Register.

    The following screen display summarizes the Error Codes.


                    Summary of Error Codes
          Returned by Byte-Oriented File I/O Routines

         Code Meaning
         ---- -------

           1  GET or PUT attempted on an unopened file
           2  Disk Full (Ran out of space)
           3  Input File Not Found
           4  Attempt to Read Past EOF
           5  Directory Full
           6  Error in Closing a File
           7  Attempt to Open a File which is already Open



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