J.READ - read absolute disk.
Usage:
iostat = j.read( buffer, device, sector
[, words, errfnc] );
Where:
- buffer
- is a pointer to where the data is to be read into.
- device
- defines the device to read from.
"device" can either be the BCD device name (e.g. `st1`),
or it can be the negative of the SCT address of the device.
- sector
- is the sector where the read starts.
- words
- is the number of words to read.
If omitted, "words" defaults to 320.
- errfnc
- is called with a PRINTF style call if there is an I/O error while
reading the disk.
If omitted, it defaults to .ERROR, which will terminate the program.
- iostat
- is the negative of the major status from the read.
A non-zero value is only returned if an "errfnc" is supplied that
does not terminate the program.
Description:
J.READ allows a privileged program to read any portion of an
online disk except the label sectors (llink 0).
In TSS, there are restrictions on the JOUT PAT used for the
actual read.
Because of this, J.READ may issue several shorter reads to satisfy
an single call to J.READ.
See Also:
- expl b syslib jio
- for an overview of the JOUT I/O routines.
Copyright © 2000, Thinkage Ltd.