Re: [Discuss-gnuradio] Issue transmitting samples using vector i/o

[Eric Blossom]

On Mon, Feb 08, 2010 at 12:23:25PM -0500, Charles Irick wrote:
> I'm running into issues with the sendmsg command in the vectorized
> send path. Depending on the buffer size I get an error returned for
> "Bad Address"
> 
> >> ethernet:write_packetv: send: Bad address
> 
> I'm working at the c++ level right now and my program is pretty simple:
> 
> usrp2::usrp2::sptr u2 = usrp2::usrp2::make(interface,mac_addr);
> 
> usrp2::tx_metadata    md;
> md.timestamp = -1;
> md.start_of_burst = 1;
> md.send_now = 1;
> 
> uint32_t buf[1000];
> u2->tx_raw(0,buf,sizeof(buf),&md);

 /*!
     * \brief transmit raw uint32_t data items to USRP2
     *
     * The caller is responsible for ensuring that the items are
     * formatted appropriately for the USRP2 and its configuration.
     * This method is used primarily by the system itself.  Users
     * should call tx_32fc or tx_16sc instead.
     *
     * \param channel specifies the channel to send them to
     * \param items are the data items to transmit
     * \param nitems is the number of items to transmit
     * \param metadata provides the timestamp and flags
     */
    bool tx_raw(unsigned int channel,
                const uint32_t *items,
                size_t nitems,
                const tx_metadata *metadata);

The 3rd arg is the number of 32-bit items.

  Try using sizeof(buf)/sizeof(buf[0])

Also, unless you're running on a big endian machine, you're going to
need to handle the endianness issue or use the slightly higher level
interfaces tx_32fc or tx16_sc.

Eric