libftdi Archives

Subject: Re: background read

From: Uwe Bonnes <bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Tue, 6 Jul 2010 19:35:51 +0200
>>>>> "Anton" == Anton A Litvinov <mirteney@xxxxxxxxx> writes:

    Anton> Thought the number 8 seems "magic" for me.  For example changing
    Anton> it to 12 leads to rare callback invocation and to floating point
    Anton> exception

    Anton> Core was generated by `./test3'.  Program terminated with signal
    Anton> 8, Arithmetic exception.  [New process 7272] #0
    Anton> 0x00007f8977a14c0a in ftdi_readstream_cb (transfer=0x19da9c0) at
    Anton> /home/anton/src/libftdi-1.0-HEAD-b013bcb/src/ftdi_stream.c:75 75
    Anton> int numPackets = (length + packet_size - 1) / packet_size;

Can you give more background, like what OS, what libusb-1 version etc.

On a first rough test serveral runs with "12" on my hardware (FT2232H in
sync fifo mode, libusb-1_0-0-1.0.6-17.1.x86_64, linux) didn't result in a

Perhaps run in gdb and when you hit the error type "p length<CR>p
packet_size <CR>" and give us the returned numbers.

The numbers where taken from the original fastftdi code.

Uwe Bonnes                bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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