UNIT(3I) Last changed: 1-6-98
NAME
UNIT - Returns the status of a BUFFER IN or BUFFER OUT statement
SYNOPSIS
UNIT ([I=]i)
IMPLEMENTATION
UNICOS, UNICOS/mk, and IRIX systems
STANDARDS
CF90 and MIPSpro 7 Fortran 90 compiler extension to Fortran 90
DESCRIPTION
After execution of asynchronous I/O with a BUFFER IN or BUFFER OUT
statement, the execution sequence continues concurrently with the data
transfer. If UNIT is called in this execution sequence, the sequence
is delayed until the transfer is complete. After the BUFFER IN
operation, use UNIT or LENGTH(3I) before using memory locations where
the data is stored. UNIT accepts the following argument:
i Must be an integer or Boolean value. Represents a unit number.
UNIT is a Fortran 90 elemental function. The name of this intrinsic
cannot be passed as an argument.
NOTES
On UNICOS and UNICOS/mk systems, UNIT can be called as either an
external subprogram or as an intrinsic procedure.
On IRIX systems, the BUFFER IN and BUFFER OUT statements are used for
synchronous I/O. Asynchronous I/O is not available through BUFFER I/O
on IRIX systems.
RETURN VALUES
When the transfer is complete, UNIT returns a value of type real. The
value is of type REAL(KIND=8) on UNICOS and UNICOS/mk systems; it is
of type REAL(KIND=4) on IRIX systems. The returned value has one of
the following meanings:
Value Meaning
-2.0 A partial-record read terminated after delivering the
requested number of words or characters, but more data
remains in the record. This status can be received only
after a BUFFER IN in partial record mode.
-1.0 Operation was completed (indicates one of the following):
* A full- or partial-record BUFFER OUT operation completed.
* A full-record BUFFER IN completed, transferring as much of
the record as would fit in the space provided.
* A partial-record BUFFER IN completed, transferring as much
data as was left in the record (no more data remains in
the record).
* UNIT was called for an unconnected unit or for a unit on
which no BUFFER IN or BUFFER OUT operations have been
performed.
0.0 An end-of-file was encountered on the previous BUFFER IN
operation. No data was transferred.
1.0 A partially recovered error occurred on the previous BUFFER
IN operation. Use the LENGTH function to determine how much
data was transferred.
2.0 An unrecovered error occurred on the last BUFFER IN or
BUFFER OUT operation.
EXAMPLES
PROGRAM TESTUNIT
DIMENSION M(200,5)
BUFFER IN(32,0) (M(1,1),M(200,5))
IF (UNIT(32) .EQ. -1.0) THEN
DO J = 1,5
DO I = 1,200
M(I,J) = M(I,J)*2
END DO
END DO
BUFFER OUT (22,0) (M(1,1),M(200,5))
IF (UNIT(22) .NE. -1.0) CALL ABORT
ELSE
CALL ABORT
ENDIF
END
SEE ALSOLENGTH(3I)
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
