Open System Services System Calls Reference Manual (G06.28+)

SPT_READX(2) OSS System Calls Reference Manual
NAME
SPT_READX - returns data from an open Guardian file to the application process data area
LIBRARY
G-series native OSS processes: /G/system/sysnn/zsptsrl
H-series OSS processes: /G/system/zdllnnn/zsptdll
SYNOPSIS
[#include <cextdecs.h>]
#include <spthread.h>
short SPT_READX (
short filenum,
char *buffer,
short read_count,
[short *count_read ],
[long tag ]
);
PARAMETERS
filenum specifies the file number of a Guardian file open instance that identifies the file to
be read.
buffer specifies an array in the application process in which the information read from
the file is returned.
read_count specifies the number of bytes to be read.
count_read is for waited I/O only. This parameter returns a count of the number of bytes
returned from the file into buffer.
tag is for nowait I/O only. The tag value you define uniquely identifies the operation
associated with this call.
This parameter is supported only for program compatibility; if you provide it, it
is ignored.
DESCRIPTION
The SPT_READX() function is the thread-aware version of the Guardian READX procedure.
The SPT_READX() function returns data from an open Guardian file to the application
process’s data area. The SPT_READX() function sequentially reads a disk file. For key-
sequenced, relative, and entry-sequenced files, the SPT_READX() function reads a subset of
records in the file. (A subset of records is defined by an access path, positioning mode, and com-
parison length.)
For programming information about the Guardian READX file-system procedure, refer to the
Guardian Programmer’s Guide, the Enscribe Programmer’s Guide, and the data communication
manuals.
General Considerations
Buffer use SPT_READX() is intended for use with 32-bit extended addresses. Therefore,
the data buffer for SPT_READX( ) can be either in the caller’s stack segment or
any extended data segment.
Waited SPT_READX( )
If a waited SPT_READX() call is executed, the count_read parameter indicates
the number of bytes actually read.
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