uhd

        usrp-e-loopback.cpp

static inline int peek16(int reg){

static inline void poke16(int reg, int val){

static inline int peek32(int reg){

static inline void poke32(int reg, int val){

//

// Copyright 2011 Ettus Research LLC

//

// This program is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//

#include "common.hpp"

#include <cstdlib>

#include <cstdio>

#include <ctime>

#include <iostream>

#include <boost/thread/thread.hpp>

#include <boost/format.hpp>

#include <boost/cstdint.hpp>

#include <sys/mman.h> //mmap

#include <unistd.h> //getpagesize

#include <poll.h> //poll

static const size_t bytes_per_frame = 2048;

static const int poll_timeout_ms = 100;

struct loopback_pkt_hdr_type{

    boost::uint32_t words32;

    boost::uint32_t checksum;

    boost::uint64_t seq_num;

};

struct loopback_pkt_type{

    loopback_pkt_hdr_type hdr;

    boost::uint32_t data[(bytes_per_frame-sizeof(loopback_pkt_hdr_type))/sizeof(boost::uint32_t)];

};

static ring_buffer_info (*recv_info)[];

static ring_buffer_info (*send_info)[];

static loopback_pkt_type (*recv_buff)[];

static loopback_pkt_type (*send_buff)[];

static struct usrp_e_ring_buffer_size_t rb_size;

static bool running = true;

static boost::uint64_t seq_errors = 0;

static boost::uint64_t checksum_errors = 0;

static boost::uint64_t sent_words32 = 0;

static boost::uint64_t recvd_words32 = 0;

static inline void print_pkt(const loopback_pkt_type &pkt){

    std::cout << std::endl;

    std::cout << "pkt.hdr.words32 " << pkt.hdr.words32 << std::endl;

    std::cout << "pkt.hdr.checksum " << pkt.hdr.checksum << std::endl;

    std::cout << "pkt.hdr.seq_num " << pkt.hdr.seq_num << std::endl;

}

boost::uint32_t my_checksum(void *buff, size_t size32){

    boost::uint32_t x = 0;

    for (size_t i = 0; i < size32; i++){

        x += reinterpret_cast<boost::uint32_t *>(buff)[i];

        x ^= reinterpret_cast<boost::uint32_t *>(buff)[i];

    }

    return x;

}

/***********************************************************************

 * Read thread - recv frames and verify checksum

 **********************************************************************/

static void read_thread(void){

    std::cout << "start read thread... " << std::endl;

    boost::uint64_t seq_num = 0;

    size_t index = 0;

    while (running){

        loopback_pkt_type &pkt = (*recv_buff)[index];

        ring_buffer_info &info = (*recv_info)[index];

        //wait for frame available

        if (not (info.flags & RB_USER)){

            pollfd pfd;

            pfd.fd = fp;

            pfd.events = POLLIN;

            if (poll(&pfd, 1, poll_timeout_ms) <= 0){

                std::cout << "Read poll timeout, exiting read thread!" << std::endl;

                running = false;

                return;

            }

        }

        info.flags = RB_USER_PROCESS;

        //print_pkt(pkt);

        //handle checksum

        const boost::uint32_t expected_checksum = pkt.hdr.checksum;

        pkt.hdr.checksum = 0; //set to zero for calculation

        const boost::uint32_t actual_checksum = my_checksum(&pkt, pkt.hdr.words32);

        if (expected_checksum != actual_checksum){

            checksum_errors++;

            std::cerr << "C";

        }

        else{

            recvd_words32 += pkt.hdr.words32;

        }

        //handle sequence

        if (seq_num != pkt.hdr.seq_num){

            seq_errors++;

            std::cerr << "S";

        }

        seq_num = pkt.hdr.seq_num+1;

        //release the packet

        info.flags = RB_KERNEL;

        //increment index and wrap around to zero

        index++;

        if (index == size_t(rb_size.num_rx_frames)) index = 0;

    }

}

/***********************************************************************

 * Write thread - send frames and calculate checksum

 **********************************************************************/

static void write_thread(const size_t num_words32){

    std::cout << "start write thread... " << std::endl;

    srandom(std::time(NULL));

    boost::uint64_t seq_num = 0;

    size_t index = 0;

    //write into tmp and memcopy into pkt to avoid cache issues

    loopback_pkt_type pkt_tmp;

    while (running){

        ring_buffer_info &info = (*send_info)[index];

        //wait for frame available

        if (not (info.flags & RB_KERNEL)){

            pollfd pfd;

            pfd.fd = fp;

            pfd.events = POLLOUT;

            if (poll(&pfd, 1, poll_timeout_ms) <= 0){

                std::cout << "Write poll timeout, exiting write thread!" << std::endl;

                running = false;

                return;

            }

        }

        //fill packet header and body

        const boost::uint32_t seed = random();

        pkt_tmp.hdr.words32 = sizeof(pkt_tmp.hdr)/sizeof(boost::uint32_t) + num_words32;

        pkt_tmp.hdr.checksum = 0; //set to zero for checksum()

        pkt_tmp.hdr.seq_num = seq_num++;

        for (size_t i = 0; i < num_words32; i++) pkt_tmp.data[i] = seed + i;

        pkt_tmp.hdr.checksum = my_checksum(&pkt_tmp, pkt_tmp.hdr.words32);

        sent_words32 += pkt_tmp.hdr.words32;

        loopback_pkt_type &pkt = (*send_buff)[index];

        std::memcpy(&pkt, &pkt_tmp, pkt_tmp.hdr.words32*sizeof(boost::uint32_t));

        //print_pkt(pkt);

        //commit the packet

        info.len = pkt_tmp.hdr.words32*sizeof(boost::uint32_t);

        info.flags = RB_USER;

        ::write(fp, NULL, 0);

        //increment index and wrap around to zero

        index++;

        if (index == size_t(rb_size.num_tx_frames)) index = 0;

    }

}

/***********************************************************************

 * Setup memory mapped ring buffer

 **********************************************************************/

static void setup_ring(void){

    std::cout << "setup memory mapped ring buffer... " << std::flush;

    //calculate various sizes

    const size_t page_size = getpagesize();

    ioctl(fp, USRP_E_GET_RB_INFO, &rb_size);

    const size_t map_size = (rb_size.num_pages_rx_flags + rb_size.num_pages_tx_flags) * page_size +

        (rb_size.num_rx_frames + rb_size.num_tx_frames) * (page_size >> 1);

    //call into memory map

    void *mem = ::mmap(0, map_size, PROT_READ|PROT_WRITE, MAP_SHARED, fp, 0);

    if (mem == MAP_FAILED) {

        std::cerr << "mmap failed" << std::endl;

        std::exit(-1);

    }

    //calculate the memory offsets for info and buffers

    const size_t recv_info_off = 0;

    const size_t recv_buff_off = recv_info_off + (rb_size.num_pages_rx_flags * page_size);

    const size_t send_info_off = recv_buff_off + (rb_size.num_rx_frames * page_size/2);

    const size_t send_buff_off = send_info_off + (rb_size.num_pages_tx_flags * page_size);

    //set the internal pointers for info and buffers

    typedef ring_buffer_info (*rbi_pta)[];

    typedef loopback_pkt_type (*pkt_pta)[];

    char *rb_ptr = reinterpret_cast<char *>(mem);

    recv_info = reinterpret_cast<rbi_pta>(rb_ptr + recv_info_off);

    recv_buff = reinterpret_cast<pkt_pta>(rb_ptr + recv_buff_off);

    send_info = reinterpret_cast<rbi_pta>(rb_ptr + send_info_off);

    send_buff = reinterpret_cast<pkt_pta>(rb_ptr + send_buff_off);

    std::cout << "done" << std::endl;

}

/***********************************************************************

 * Main

 **********************************************************************/

#include <boost/program_options.hpp>

int main(int argc, char *argv[]){

    //variables to be set by po

    double duration;

    size_t nwords;

    //setup the program options

    namespace po = boost::program_options;

    po::options_description desc("Allowed options");

    desc.add_options()

        ("help", "help message")

        ("duration", po::value<double>(&duration)->default_value(10), "number of seconds to run loopback")

        ("nwords", po::value<size_t>(&nwords)->default_value(400), "number of words32 to send per packet")

    ;

    po::variables_map vm;

    po::store(po::parse_command_line(argc, argv, desc), vm);

    po::notify(vm);

    //print the help message

    if (vm.count("help")){

        std::cout << boost::format("UHD USRP-E-Loopback %s") % desc << std::endl;

        return ~0;

    }

    if ((fp = ::open("/dev/usrp_e0", O_RDWR)) < 0){

        std::cerr << "Open failed" << std::endl;

        return -1;

    }

    //set the mode to loopback

    poke16(E100_REG_MISC_XFER_RATE, (1<<8) | (1<<9));

    //setup the ring buffer

    setup_ring();

    //spawn threads

    boost::thread_group tg;

    tg.create_thread(boost::bind(&read_thread));

    tg.create_thread(boost::bind(&write_thread, nwords));

    const boost::system_time start_time = boost::get_system_time();

    const boost::system_time finish_time = start_time + boost::posix_time::milliseconds(long(duration*1000));

    while (boost::get_system_time() < finish_time){

        boost::this_thread::sleep(boost::posix_time::milliseconds(1000));

        std::cerr << ".";

    }

    running = false;

    tg.join_all();

    std::cout << std::endl;

    std::cout << "seq_errors          " << seq_errors << std::endl;

    std::cout << "checksum_errors     " << checksum_errors << std::endl;

    std::cout << "sent_words32        " << sent_words32 << std::endl;

    std::cout << "recvd_words32       " << recvd_words32 << std::endl;

    std::cout << "approx send rate    " << (sent_words32/duration)/1e6 << "Msps" << std::endl;

    std::cout << "approx recv rate    " << (recvd_words32/duration)/1e6 << "Msps" << std::endl;

    ::close(fp);

    return seq_errors + checksum_errors;

}