[fpc-pascal] Serial to TCP gateway in FPC?

José Mejuto joshyfun at gmail.com
Thu Jun 29 14:38:50 CEST 2017


El 29/06/2017 a las 10:39, Bo Berglund escribió:

> 3) I also noted in the comments in TurSeriale.pas:
>    "The Windows port driver does receive callbacks in chunks that
>     are typically 8 bytes long.
>     With ReceiveMode = rmRAW, TSeriale will simply pass this chunks
>     on to the application without any processing."
> Does this mean that if a single character is received it is not passed
> along? My protocol is exchanging single bytes for state changes and

Hello,

I'm quite sure no, it means that the driver will try to queue 8 bytes 
before sending back data, but the tricky word is "try", probably after a 
context switch or similar the available data will be reported by the 
driver whichever the amount of bytes are.

Kernel to userland data pass is very expensive so drivers usually try to 
queue a data amount limit or a data time limit whichever it happens first.

Also forget the usual 15 bytes buffering in serial comms, it is expected 
that the kernel driver can buffer much more data before overflow, 
probably around 8 Kbs.

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