Date: Thu, 23 Jul 2009 08:33:42 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Alexey Shuvaev <shuvaev@physik.uni-wuerzburg.de>, Alexander Best <alexbestms@math.uni-muenster.de> Subject: Re: checking number of parallel ports installed and their port adresses Message-ID: <200907230833.43021.jhb@freebsd.org> In-Reply-To: <permail-200907221931541e86ffa800007bf8-a_best01@message-id.uni-muenster.de> References: <permail-200907221931541e86ffa800007bf8-a_best01@message-id.uni-muenster.de>
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On Wednesday 22 July 2009 3:31:54 pm Alexander Best wrote: > the ppi manual states that using ioctl with /dev/ppi is extremely slow. i need > the parallel port to be really fast. i need to communicate with a device that > uses asynchronous transfer at a rate of ~ 2 mhz. so i need the full ISA bus > speed to be able to push/pull data to/from the parallel port without any > delays. timing is really critical. if there's a lot of work to do for the > scheduler and the io calls get queued too long the transfer will fail. The overhead of ppi is probably in the noise on a modern CPU. I think you should be fine with just using ppi(4). > actually i meant: how can i check the available parallel ports from within my > app? is there a syscall i can use or something like that? You can look for ppcX devices perhaps. The easiest way might be to enable ppi and look for /dev/ppiX devices in /dev. -- John Baldwin
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