Guardian Procedure Calls Reference Manual

You set the odd unstructured attribute with the FILE_CREATE_, FILE_CREATELIST_, or
CREATE procedure, or with the File Utility Program (FUP) SET and CREATE commands.
◦ FILE_READ64_ count
Unstructured files are transparently blocked. The BUFFERSIZE file attribute value, if not
set by the user, defaults to 4096 bytes. The BUFFERSIZE attribute value (which is set by
specifying SETMODE function 93) does not constrain the allowable read-count in any
way. However, there is a performance penalty if the FILE_READ64_ does not start on a
BUFFERSIZE boundary and does not have a read-count that is an integral multiple of
the BUFFERSIZE. The DP2 disk process executes your requested I/O in (possibly multiple)
units of BUFFERSIZE blocks starting on a block boundary.
◦ count-read for unstructured FILE_READ64_ calls
After a successful call to FILE_READ64_ for an unstructured file, the value returned in
count-read is determined by:
count-read := $MIN(read-count & eof-pointer - next-record pointer)
◦ Pointers after FILE_READ64_
After a successful FILE_READ64_ to an unstructured file, the file pointers are:
– CCG = 1 if the next-record pointer = EOF pointer; otherwise CCG = 0
– current-record pointer = old next-record pointer
– next-record pointer = old next-record pointer + count-read
Related Programming Manuals
For programming information about the FILE_READ64_ procedure, see the Guardian Programmer's
Guide, the Enscribe Programmer's Guide, and the data communication manuals.
FILE_READ64_ Procedure 481