Guardian Procedure Calls Reference Manual

Parameters
filenum
input
INT:value
is the number of an open file that identifies the file to be read.
buffer
output
(for READUPDATE)INT:ref:*
(for READUPDATEX and READUPDATEXL)STRING .EXT:ref:*
is an array where the information read from the file returns.
read-count
input
(for READUPDATE and READUPDATEX)INT:value
(for READUPDATEXL)INT(32):value
is the number of bytes to be read:
for disk files (see Disk File Considerations (page 1196)){0:4096}
for $RECEIVE (with READUPDATE and READUPDATEX){0:57344}
for $RECEIVE (with READUPDATEXL){0:2097152}
count-read
output
(for READUPDATE)INT:ref:1
(for READUPDATEX)INT .EXT:ref:1
(for READUPDATEXL)INT(32) .EXT:ref:1
is for wait I/O only. count-read returns a count of the number of bytes returned from the
file into buffer.
tag
input
(for READUPDATE and READUPDATEX)INT(32):value
(for READUPDATEXL)INT(64):value
is for nowait I/O only. tag is a value you define that uniquely identifies the operation associated
with this READUPDATE[X|XL]. If the completed I/O operation has a 32-bit tag, the 64-bit tag
is in the sign-extended value of the 32-bit tag.
NOTE: The system stores the tag value until the I/O operation completes. The system then
returns the tag information to the program in the tag parameter of the call to AWAITIO[X|XL],
thus indicating that the operation completed. If READUPDATEX or READUPDATEXL is used, you
must call AWAITIOX or AWAITIOXL to complete the I/O. If READUPDATE is used, you may
use either AWAITIO or AWAITIOX or AWAITIOXL to complete the I/O.
READUPDATE[X|XL] Procedures 1215