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From: Hans-Peter Diettrich <DrDiettrich1@aol.com>
Newsgroups: comp.lang.pascal.delphi.misc
Subject: Re: Delphi D4: using pointers to transfer data from COMM queue to circular queue
Date: Fri, 19 Aug 2016 12:27:25 +0200
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P E Schoen schrieb:
> I have an application that uses a serial port component to read and 
> write data through a USB serial port at 57.6 kb. Originally I used the 
> SerialNG component and with some tweaking I was able to get it to work 
> reliably. But it has problems with Win10, so I changed the code to use 
> ComDrv32, which works when used in a simple TTY demo.

I don't remember what prevented programs from using the asynchronous I/O 
API. 57kbd also doesn't look like a dangerous transmission speed.


> I had to use a separate PChar pointer RecdPtr, and I also had to use an 
> integer for the pointer arithmetic. Apparently Delphi does not allow 
> RecdPtr := RecdPtr + (DataSize - (MAXCOMM-CommBufferPtr) ); RecdPtr + n 
> is OK. I'm not sure if I could just advance the DataPtr in the same way, 
> since it is declared as a generic Pointer type.

Delphi allows pointer math only with PCHAR. At least I'd use Cardinal 
instead of Integer, in a workaround.

DoDi