Device Request 03H: IOCTL Input
◄Blk► ◄Chr► ◄IRW►
This tells the driver to send some IOCTL data to DOS.
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+0 1 bLen 14H (length of this request packet)
+1 1 bUnitNo unit number
+2 1 bCmd 03H (command code)
+3 2 rStatus OUTPUT: Device Status Word must fill before exit
+5H 8 res (reserved)
+0dH 1 bData (not used)
+0eH 4 pfBuffer INPUT: buffer address
+12H 2 wLen INPUT: size of data requested (in bytes)
OUTPUT: actual size of data being returned
20 size of this structure
rStatus On exit, the driver must place a DevStatusWord here. Always
set the Done bit (bit 8). On an error, set the Done bit and
the Error bit (bit 15) and put a Device Error Code in the low
pfBuffer is the address of a buffer in which the driver may place the
requested data. You must not store more than wLen bytes here.
wLen On entry, this specifies the size of the data DOS is
requesting, in bytes.
On exit, you must store the actual size of the data that you
Notes: ■ The layout of the data in pfBuffer is entirely device-specific
and will vary from device to device.
■ There is no way to specify just what type of data is requested.
See DvRq 13H (generic IOCTL) for a more flexible system.
■ This is the device driver "catch-point" for DOS fns 4402H and
4404H (receive IOCTL data).
See Also: Device Requests
Installable Device Drivers