RD.RAN/WR.RAN - ***DELETED*** use READ/WRITE.
Usage:
rd.ran( filevec, buffer [, sector [, nwds] ] );
wr.ran( filevec, buffer [, sector [, nwds] ] );
Where:
- filevec
- is the "ret" vector returned by ACC.FIL. In
batch, the first word will contain the BCD filecode, and
in TSS the first two words will contain the aftname. The
status return and file descriptor words are used by
RD.RAN and WR.RAN.
- buffer
- is a buffer into which RD.RAN places the data it reads,
and from which WR.RAN takes the data it writes.
"buffer" must be big enough to hold
"nwds".
- sector
- is the starting sector address in the file which is being
read or written. A sector is 64 words long and the first
sector of the file has a sector address of zero. If
"sector" is not specified, the default is zero.
- nwds
- is the number of words to read or write. When writing, if
"nwds" is not a multiple of 64, the hardware
writes zeroes onto the remaining fraction of a sector. If
"nwds" is not specified, the default is 320
words for both reading and writing. "nwds" must
lie between 1 and 4096 inclusive.
Description:
RD.RAN and WR.RAN are used to perform binary I/O on random
files which have been opened by a call to ACC.FIL.
In WR.RAN, if the write gets an eof status, it will attempt to
grow the file by the amount needed to hold the data. If the grow
succeeds, the write is reissued. If the grow fails, WR.RAN will
not make a second attempt at growing the file.
In TSS, an eof status will be faked if an attempt is made to
read from a null file.
It is recommended that you use the routines READ and WRITE
instead of RD.RAN and WR.RAN. If you feel you must use RD.RAN and
WR.RAN, remember that they only work on random files.
See Also:
- expl b lib read
- for the recommended functions.
- expl b lib acc.fil
- for the format of "filevec".
- expl b lib .grow
- for details on the file growth algorithm.
Copyright © 1996, Thinkage Ltd.