[Linux-parport] mimic a printer for capturing to file

Uwe Sander uvosa at gmx.de
Fri Apr 30 08:33:16 EDT 2010


 sorry for my english, german is my native language.

Have a strange problem when reading from the parallel port in a
poll()-ioctl(fd, PPRDATA, &data)-loop:

- It seems the driver does a buffered read in 4 Kb blocks.
- When i read from the port the first byte is hold back and send at the
end of the current 4k-block.
- When the transfer ends, the first byte ist placed at the last write

Does anybody know this behaviour? Any hint?

I am using Ubuntu 9.10 (2.6.31-21-generic) and Debian 4.

Thanks a lot!


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