Re: [Discuss-gnuradio] updated packet format on USRP inband signaling

[Brian Padalino]

On 2/26/07, Eric Blossom <address@hidden> wrote:
> On Mon, Feb 26, 2007 at 09:44:37PM +0100, Martin Dvh wrote:
> > MASKED_WRITE:
> > What I also miss is a masked write to registers:
> > Write Register:
> >
> >           Opcode:     OP_WRITE_REG_MASKED
> >
> >          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >          |     Opcode    |       6       |    mbz    |     Reg Number    |
> >          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >          |                        MASK                                   |
> >          |                        Register Value                         |
> >          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >
> > A Masked write would save you from needing to do a read, modify,
> > write over the BUS when you only want to change a single bit.
>
> Good idea.  I'll add it.

Can't the host figure out what the new value should be using its
shadowed values?  Under which circumstances would you want to use the
mask without the host already knowing the contents of the register if
it had already been written?

Another concern I had was with multiple read commands and the
timestamp.  If a control packet is sent down with multiple read
commands and a timestamp of NOW - the first read is done ASAP and the
timestamp field filled with the current time.  Is this the way it
should work, or should the timestamp represent the time the last piece
of data was read?  Should there be some other type of message which
states a second timestamp at the end of the received control packet to
say how long it took for the operation to complete?

Brian