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Sequentially reads a physical block of user-specified size from a KSAM/XL
file. Syntax | |
I32 REC I32 A
lgth := AIFKSMREAD (overall_status, filenum, buffer,
I32 I32
bytes, user_id);
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Functional Return | |
- lgth
32-bit signed integer by reference (required) Returns a positive integer value indicating the length of the information
transferred.
Parameters | |
- overall_status
record by reference (required) Returns the overall status of the call. A zero indicates a successful call.
A negative value indicates an error in the overall call. Refer to appendix A
for meanings of status values. - filenum
32-bit signed integer by value (required) An identifier supplying the file number of the file
to be read. - buffer
character array by reference (required) An array to hold a physical block of the KSAM/XL file.
The content in the buffer returned from the first AIFKSMREAD
after the KSAM/XL file is opened is used by AIFKSMCREATE
to duplicate a KSAM/XL file.
The contents returned from subsequent AIFKSMREADs are
used by AIFKSMWRITEs to copy to the new KSAM/XL file. The minimum buffer size is 10,240 bytes. - bytes
32-bit signed integer by value (required) A positive integer specifying the number of bytes to be transferred.
If this value is zero, no transfer occurs.
If bytes is larger than the remaining physical block size,
transfer is limited to the length up to EOF. - user_id
32-bit signed integer by value (optional) The user ID assigned to a vendor at the time of purchase of the Architected Interface Facility: Operating System product.
Operation Notes | |
The AIFKSMREAD call reads a block from a KSAM/XL file in its physical sequence.
The KSAM/XL file must have been opened in copy mode with MR and NOBUF options and
read-only access in
order to call this procedure. The first AIFKSMREAD after the file is opened
transfers all of the necessary information required by
AIFKSMCREATE.
The buffer size and the bytes count must be large enough to hold the
information to be passed to AIFKSMCREATE.
The minimum size required may vary depending on the size of user
labels. In the case where no user label exists in the file, the minimum size
required is 10240 bytes.
It is recommended that the buffer size and the bytes count be multiples of 4096
and 65536 bytes (16 pages).
At the end of AIFKSMREAD procedure, the data pointer is positioned to the byte
following the last byte being read.
AIFKSMREAD transfers only the in-use areas and ignores the unused area in the
KSAM/XL file. An end-of-file status is returned if AIFKSMREAD is called
after the last byte of the file is transferred. The AIFKSMREAD procedure returns a positive integer value to lgth showing
the length of the information transferred. Both lgth and bytes in
the AIFKSMREAD call must be positive numbers representing bytes counts. |
