Accessing Files Programmer's Guide (32650-90885)
40 Chapter2
Creating A File
The HPFOPEN Intrinsic
44/I32 Numbuffers:
Passes the number of buffers to allocate to the file. Ignored for standard
disk files. This option is useful only for slow devices (such as tapes) used in
a buffered mode. Not applicable for files representing interactive
terminals; a system-managed buffering method is always used.
The valid range for this option is dependent upon the file type:
• For standard and KSAM files, the valid range is 1..31.
• For circular and RIO files, the valid range is 1..16.
• For message files, the valid range is 2..16. (If a 1 is specified, the file
system sets this option to 2 and no error is returned.)
This option must not specify a number of buffers whose combined size
exceeds the physical capacity of the file.
This
itemnum
is ignored when creating hierarchical directories.
Default: 2
(ASC) Not used for asynchronous devices.
45/CA Fill character:
Passes two ASCII characters that determine what padding character to
use at the end of blocks or unused pages, and the padding used by
itemnum
=53. Do not use delimiter characters for this option. The fill
character must be a 2 byte array. The first character only is used as the
padding character. The second character is reserved for future use. This
option is applicable only at file creation.
Default: Null characters for a binary file and ASCII blanks for an ASCII
file.
The default fill character for byte stream files is the null character. The fill
character is null for hierarchical directories regardless of the value
specified for this
itemnum
.
46/I32 Inhibit buffering:
Passes a value enabling/disabling automatic operataing systembuffering.
If NOBUF is specified, I/O is allowed to take place directly between the data
area and the applicable hardware device.
The following values are valid:
0 Allow normal buffering (BUF)
1 Inhibit buffering (NOBUF)
Default: 0
NOBUF access is oriented to physical block transfer rather than logical
record transfer. If NOBUF and a variable-length record structure are
specified in
itemnum
=6 and the file does not have a variable-length record
format, then the format is changed internally to an undefined-length
record format. When performing an FWRITE, set up the variable structure.