Jeff Lindberg wrote:
>Ross Scroggs ([log in to unmask]) wrote:
[snip]
>
>Ross, I am (almost) certain that it would be do-able (I got *so* close
>when I was trying to port Zmodem code some years back) by using typeahead
>- IF ONLY - there were some mechanism to retrieve the number of characters
>in the DTC input buffer so one could issue a non-blocking read for that
>exact number of characters.
[snip]
>At least it looked good on the drawing board until I realized there was
>no way to get the number of bytes in the DTC input buffer... ;-)
 
Reading count of characters in the type-ahead buffer would be nice, but not
sufficient: that number can change between the time you get it and the time
you issue the read. If I can't get true full duplex, what I'd prefer is a
way to do a timed read with a true zero value for the timeout. The read
would return immediately with whatever characters were in the typeahead
buffer, returning the count as always. This could also be implemented with
an FDEVICECONTROL since the semantics are slightly different from a normal
terminal read.
 
Of course, the nicest would be true full-duplex: if I do a second FOPEN of
the port, I have some option that says I want a completely separate path to
the port. I'd be willing to live with the restriction that says there can
be only one of these special FOPENs in each direction for any given port,
and that they take priority over any other FOPENs.
 
-- Bruce
 
>| "Any technology, sufficiently      || "Any technology, sufficiently       |
>|  advanced, is indistinguishable    ||  advanced, is indistinguishable     |
>|  from magic."  -- Arthur C. Clarke ||  from a household appliance." -- me |
 
Or my favorite, "Any technology, sufficiently advanced, is
indistinguishable from a rigged demo."
 
-- B
 
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