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INPUT/OUTPUT FUNCTIONS
25.3 --
Device
Independent
IIO Functions
the bit was
set
to
one
before
the
. REWND
c a
11
wa
s i s sue
d ,
$
pac a ma
~
have been deallocated from
the
file
and
the
end-aT-fila
pointer in the
RIB
updated.
The
remainde~
of IOCDTT
is
unchanged.
IOCMLS
contains
the value SFFFF.
IOCSDW
contains
the
first SDW from
the
file's RIB.
IOCSLS
contains
the
value
$FFFF.
IOCLSN
contains the value
zero.
IOCEOF
contains the LSN
of
the
logical
end-af-file from the file's RIB.
IOCSBP
contains the value zero.
IoeSBI
contains
the value
in
IOeSBE.
The
remainder-
Q~
the IOCE
is
unchanged.
The
contents
Or
the
sector
buff~r
are
indeterminate.
The effect
of
rewinding
a
file
is
the
same
as
iF
a
.CLOSE
and
a .
OPEN
function
were performedi
howeverl
the
.REWND
Function
reopens
the
file
without
having
the
calling
program
re-speci~q
the
file's
name
and
suf-rix.
Thusl
when
the
file
is
rewoundl
the same space deallocation
and
end-Or-file
pointer
considerations
take ef-rect as if the
file were closed.
Since the truncate
Tlag
is
set to zero after the .REWND
call (opening
an
existing file),
the
calling program may have to reset the
flag ir
space
is to be deallocated or
the
end-or-rile pointer updated upon
calling
the
subsequent
.
CLOSE
function.
25.3.9.4 Example of logical sector IIO
The
following
example
uses
the
logical
sector
IIO
functions.
The IDCB shown below is used in
the
example
as
the
°control block for reading rrom and writing to a
diskette
file.
The
initial values
set up
in
this lOeB are
similar
to
Page
25-58
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