MPE/iX Intrinsics Reference Manual (32650-90875)

236 Chapter6
Command Definitions (FLUSHLOG-GETUSERMODE)
FOPEN
transfer whole blocks leave the next record pointer set to the first record in
the next block. The EOF marker always points at the last record in the file.
For files opened NOBUF, the FREADDIR, FWRITEDIR, and FPOINT intrinsics
treat the
recnum parameter as a block number.
Indicate non-RIO access to an RIO file by specifying the file NOBUF. Use the
physical block size from FFILEINFO to determine the maximum transfer
length.
For message files, the file system normally resets the inhibit buffering
option bit to zero. However, a message file can be opened with NOBUF if the
copy mode option (
aoption bit (3:1)) is set to 1; this determines whether
access to the file is record-by-record or by block.
If you are reading a message file with the copy mode option enabled, the
inhibit buffering option has the following meaning:
0 Read by logical record
1 Read by physical block
If writing to a message file, open it NOBUF; if the copy mode option is
enabled, access the file block-by-block.
(ASC) Not valid for asynchronous device files.
5:2 Multiaccess mode option
Indicates how the file's record pointer is to be shared. This option is useful
for sharing standard input devices where there is some natural sequence
of access to the file. This option permits processes located in different jobs
or sessions to open the same file and share that file's record pointer.
The following bit settings are valid:
00 No MULTI access. A unique record pointer is created for
this access to the file.
For message files, the default value of bits (5:2) is 10 for
normal access, or is 00 for copy mode access.
01 Intrajob MULTI access only allowed. A record pointer is
shared with all other opened files of the same name in the
same job/session who opened the file with this option set to
either 01 or 10.
10 Interjob MULTI access allowed. A record pointer is shared
with all other opened files of the same name on the
system.
Default: 0
(ASC) Not valid for asynchronous device files.
4:1 Nowait I/O option
Enables/disables nowait I/O. Determines whether or not the accessor has
control returned before the completion of an I/O request. The nowait I/O