2011/3/23 Brendan Simon (eTRIX) <brendan.si...@etrix.com.au>: > The pyusb tutorial has an example of using the control transfer functions. > > http://pyusb.sourceforge.net/docs/1.0/tutorial.html > >>>> msg = 'test' >>>> assert dev.ctrl_transfer(0x40, CTRL_LOOPBACK_WRITE, 0, 0, msg) == len(msg) >>>> ret = dev.ctrl_transfer(0x40, CTRL_LOOPBACK_READ, 0, 0, len(msg)) >>>> sret = ''.join([chr(x) for x in ret]) >>>> assert sret == msg > > > I was wondering if it would be better (or more efficient) to use some of > the array functions. > e.g. > >>>> sret = ''.join(ret.tolist()) > > or > >>>> sret = ret.tostring() > The best way to know it is to measure, I guess.
> > Any thoughts on this ?? > > Also, just out of curiosity, what is the advantage of returning/using an > array object rather than a string ?? > If you think from PyUSB point of view, things returned by the device are raw data, not string's. There is an abstraction stuff there. Moreover, because of portability across different Python versions, I use array objects internally, thus makes sense to return these objects. > Why is a string object used for WRITE instead of a string ?? > The WRITE and READ transfers seem a little inconsistent in the object > written and returned. > Write accepts any kind of sequence that an array object accepts in its constructor. On the return of a read, I do need to return something, I cannot return such a generic sequence, as in write's. -- Best Regards, Wander Lairson Costa LCoN - Laboratório de Computação Natural - Natural Computing Laboratory (http://www.mackenzie.com.br/lcon.html) Programa de Pós-Graduação em Engenharia Elétrica (PPGEE) Faculdade de Computação e Informática (FCI) Universidade Presbiteriana Mackenzie - SP - Brazil ------------------------------------------------------------------------------ Enable your software for Intel(R) Active Management Technology to meet the growing manageability and security demands of your customers. Businesses are taking advantage of Intel(R) vPro (TM) technology - will your software be a part of the solution? Download the Intel(R) Manageability Checker today! http://p.sf.net/sfu/intel-dev2devmar _______________________________________________ pyusb-users mailing list pyusb-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pyusb-users
