Re: [Discuss-gnuradio] Discuss

[Michael Dickens]

On Mar 15, 2009, at 2:10 PM, Johnathan Corgan wrote:
> On Sun, Mar 15, 2009 at 11:03 AM, Philip Balister  
> <address@hidden> wrote:
> > On a related note, does anyone know why the usrp code has to look  
> > at value
> > obtained from the internals of libusb? With libusb-1, this value is  
> > no
> > longer accessible.
>
> We use libusb for housekeeping, but interact directly with the file
> descriptor it creates (for performance reasons).
>
> It's something we'll have to revisit soon as distributions move to  
> libusb-1.

The USRP's FUSB code for Darwin / OSX does the same thing with libsub  
0.1.12: use LIBUSB for parsing currently available USB devices &  
related housekeeping, and making use of LIBUSB's internal structures  
and variables to find information about the file descriptors but using  
custom code to do the actual data I/O (again, for performance reasons:  
libusb 0.1 series provides only synchronous data I/O on Darwin).

IIRC, the libusb 1.0 series currently works only on Linux but does  
provide an API for extending to other platforms.  This OS limitation,  
obviously, makes it an issue for GNU Radio & other solidly cross-OS  
projects.

That said, there is a "libusb-compat-0.1 compatibility layer" for  
libusb 1.0 ... anyone tested this out for various-OS usability?   
Reading through the source code it looks like Linux-only.

< http://libusb.wiki.sourceforge.net/LibusbCompat0.1 > - MLD