On Thu, Mar 15, 2007 at 04:36:56PM +0100, Davide Anastasia wrote:
> Il giorno gio, 15/03/2007 alle 08.10 -0700, Eric Blossom ha scritto:
> > Davide,
> >
> > In the code that we distribute, yes. However, I think you're asking
> > about the code that you have been modifying in the FPGA. You're in
> > charge of that part. What are you doing?
>
> I'm working on usrp1_source_s.cc to obtain an unpacked stream of 1 bit
> samples into char variables (no changes for short). So, if I have 1, I
> wish to use 0x00000001 and 0x00000000 for 0 value. I guess it is
> reasonable, because after I can use unpacked_to_packed and
> packed_to_unpacked to obtain a stream of bit of byte. I fault?
>
> > In the unmodified code, we push 16-bit I & Q across the interface to
> > the FX2 and from there to the host. The data comes out I first, then
> > Q, and each 16-bit value is little-endian byte order.
>
> Because Peter Monta' patch use a mask like this 16'b0000000000000001, I
> need to give to a 16 bit sample a 15 bit shift to take the SIGN. Isn't
> it??
>
> Regards,
> --
> Davide Anastasia
>
> web: http://www.davideanastasia.com/
> email: [EMAIL PROTECTED]
I Davide,
I think you'll find it easier to do the unpacking in a separate block
downstream from the usrp1_source_s. Modifying usrp1_source* to handle
samples smaller than 1 byte is going to take quite a bit of work. Part
of the problem is that the code is written in terms of functions such
as sizeof_basic_sample() which returns a size in bytes. In your case,
your basic sample is smaller than a byte. The current code doesn't
know how to deal with that.
After unpacking, what representation do you want for your samples?
If bytes containing 1-bit per byte are OK, then perhaps the easiest
approach is to create a gr_packed_to_unpacked_sb.*
You should be able to do this by changing:
# other blocks
others = (
('gr_chunks_to_symbols_XX', ('bf', 'bc', 'sf', 'sc', 'if', 'ic')),
('gr_unpacked_to_packed_XX', ('bb','ss','ii')),
('gr_packed_to_unpacked_XX', ('bb','ss','ii'))
)
to
# other blocks
others = (
('gr_chunks_to_symbols_XX', ('bf', 'bc', 'sf', 'sc', 'if', 'ic')),
('gr_unpacked_to_packed_XX', ('bb','ss','ii')),
('gr_packed_to_unpacked_XX', ('bb','ss','ii', 'sb'))
)
in gnuradio-core/src/lib/gengen/generate_common.py
On the other hand, I assume that ultimately these end up as some kind
of complex data type, so perhaps some other kind of mapping to
gr_complex would be useful.
Eric
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