Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

218 Chapter8
Intrinsics Reference
FDEVICECONTROL
57 Obtain subsystem break character.
This directive returns the current subsystem break
character. It only returns a value, and may not be used
to change the subsystem break character.
60 Flush typeahead buffer.
This directive flushes the typeahead buffer. If buffer
equals 1, the device driver flushes the typeahead buffer,
and any data in the buffer is lost. This request is valid
for the next read only. A value of 0 has no effect on the
typeahead buffer. This request is only valid if
typeahead is enabled. (See parm1 = 51)
If issued against a terminal connected via PAD or DTC
Telnet, this call will return a CCE condition code, but
the device control action will not occur. If issued against
a terminal connected via VT to an MPE V system, this
call will return an error.
61 Bypass typeahead buffer.
This directive specifies that the next read shall be
taken from the terminal and not the typeahead buffer.
If buffer is 1, the next read will receive data directly
from the device; the read bypasses any data in the
typeahead buffer. The data in the typeahead buffer will
not be flushed, and can be obtained by subsequent
reads. The request is valid for the next read only. A
buffer value of 0 allows the typeahead buffer to
function normally. (See parm1 = 51)
You may use this directive to obtain status information
directly from a device. This request is only valid if
typeahead is enabled.
If issued against a terminal connected via PAD or DTC
Telnet, this call will return a CCE condition code, but
the device control action will not occur. If issued against
a terminal connected via VT to an MPE V or HP-UX
system, this call will return an error.
62 Quiesce I/O.
This directive ensures that all outstanding nowait I/O
operations have completed. If buffer is 1, the call to
FDEVICECONTROL does not complete until all nowait
I/O operations have been fulfilled for the device. A
buffer value of 0 has no effect, and returns
immediately.