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-rw-r--r--host/lib/usrp/cores/CMakeLists.txt4
-rw-r--r--host/lib/usrp/cores/rx_dsp_core_200.cpp164
-rw-r--r--host/lib/usrp/cores/rx_dsp_core_200.hpp51
-rw-r--r--host/lib/usrp/cores/rx_frontend_core_200.cpp28
-rw-r--r--host/lib/usrp/cores/rx_frontend_core_200.hpp16
-rw-r--r--host/lib/usrp/cores/tx_dsp_core_200.cpp123
-rw-r--r--host/lib/usrp/cores/tx_dsp_core_200.hpp44
-rw-r--r--host/lib/usrp/cores/tx_frontend_core_200.cpp16
-rw-r--r--host/lib/usrp/cores/tx_frontend_core_200.hpp16
9 files changed, 462 insertions, 0 deletions
diff --git a/host/lib/usrp/cores/CMakeLists.txt b/host/lib/usrp/cores/CMakeLists.txt
index 5b2997131..4476c9424 100644
--- a/host/lib/usrp/cores/CMakeLists.txt
+++ b/host/lib/usrp/cores/CMakeLists.txt
@@ -25,4 +25,8 @@ LIBUHD_APPEND_SOURCES(
${CMAKE_CURRENT_SOURCE_DIR}/i2c_core_100.cpp
${CMAKE_CURRENT_SOURCE_DIR}/spi_core_100.cpp
${CMAKE_CURRENT_SOURCE_DIR}/time64_core_200.cpp
+ ${CMAKE_CURRENT_SOURCE_DIR}/rx_dsp_core_200.cpp
+ ${CMAKE_CURRENT_SOURCE_DIR}/tx_dsp_core_200.cpp
+ ${CMAKE_CURRENT_SOURCE_DIR}/rx_frontend_core_200.cpp
+ ${CMAKE_CURRENT_SOURCE_DIR}/tx_frontend_core_200.cpp
)
diff --git a/host/lib/usrp/cores/rx_dsp_core_200.cpp b/host/lib/usrp/cores/rx_dsp_core_200.cpp
new file mode 100644
index 000000000..e4d88b38f
--- /dev/null
+++ b/host/lib/usrp/cores/rx_dsp_core_200.cpp
@@ -0,0 +1,164 @@
+//
+// 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 "rx_dsp_core_200.hpp"
+#include <uhd/types/dict.hpp>
+#include <uhd/exception.hpp>
+#include <boost/assign/list_of.hpp>
+#include <boost/math/special_functions/round.hpp>
+#include <boost/math/special_functions/sign.hpp>
+#include <algorithm>
+#include <cmath>
+
+#define REG_DSP_RX_FREQ _dsp_base + 0
+#define REG_DSP_RX_DECIM _dsp_base + 1
+#define REG_DSP_RX_MUX _dsp_base + 2
+
+#define FLAG_DSP_RX_MUX_SWAP_IQ (1 << 0)
+#define FLAG_DSP_RX_MUX_REAL_MODE (1 << 1)
+
+#define REG_RX_CTRL_STREAM_CMD _ctrl_base + 0
+#define REG_RX_CTRL_TIME_SECS _ctrl_base + 1
+#define REG_RX_CTRL_TIME_TICKS _ctrl_base + 2
+#define REG_RX_CTRL_CLEAR _ctrl_base + 3
+#define REG_RX_CTRL_VRT_HDR _ctrl_base + 4
+#define REG_RX_CTRL_VRT_SID _ctrl_base + 5
+#define REG_RX_CTRL_VRT_TLR _ctrl_base + 6
+#define REG_RX_CTRL_NSAMPS_PP _ctrl_base + 7
+#define REG_RX_CTRL_NCHANNELS _ctrl_base + 8
+
+using namespace uhd;
+
+class rx_dsp_core_200_impl : public rx_dsp_core_200{
+public:
+ rx_dsp_core_200_impl(
+ wb_iface::sptr iface,
+ const size_t dsp_base, const size_t ctrl_base,
+ const boost::uint32_t sid, const size_t nsamps
+ ):
+ _iface(iface), _dsp_base(dsp_base), _ctrl_base(ctrl_base)
+ {
+ _iface->poke32(REG_RX_CTRL_CLEAR, 1); //reset
+ _iface->poke32(REG_RX_CTRL_NSAMPS_PP, nsamps);
+ _iface->poke32(REG_RX_CTRL_NCHANNELS, 1);
+ _iface->poke32(REG_RX_CTRL_VRT_HDR, 0
+ | (0x1 << 28) //if data with stream id
+ | (0x1 << 26) //has trailer
+ | (0x3 << 22) //integer time other
+ | (0x1 << 20) //fractional time sample count
+ );
+ _iface->poke32(REG_RX_CTRL_VRT_SID, sid);
+ _iface->poke32(REG_RX_CTRL_VRT_TLR, 0);
+ }
+
+ void issue_stream_command(const stream_cmd_t &stream_cmd){
+ UHD_ASSERT_THROW(stream_cmd.num_samps <= 0x3fffffff);
+ _continuous_streaming = stream_cmd.stream_mode == stream_cmd_t::STREAM_MODE_START_CONTINUOUS;
+
+ //setup the mode to instruction flags
+ typedef boost::tuple<bool, bool, bool> inst_t;
+ static const uhd::dict<stream_cmd_t::stream_mode_t, inst_t> mode_to_inst = boost::assign::map_list_of
+ //reload, chain, samps
+ (stream_cmd_t::STREAM_MODE_START_CONTINUOUS, inst_t(true, true, false))
+ (stream_cmd_t::STREAM_MODE_STOP_CONTINUOUS, inst_t(false, false, false))
+ (stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE, inst_t(false, false, true))
+ (stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_MORE, inst_t(false, true, true))
+ ;
+
+ //setup the instruction flag values
+ bool inst_reload, inst_chain, inst_samps;
+ boost::tie(inst_reload, inst_chain, inst_samps) = mode_to_inst[stream_cmd.stream_mode];
+
+ //calculate the word from flags and length
+ boost::uint32_t cmd_word = 0;
+ cmd_word |= boost::uint32_t((stream_cmd.stream_now)? 1 : 0) << 31;
+ cmd_word |= boost::uint32_t((inst_chain)? 1 : 0) << 30;
+ cmd_word |= boost::uint32_t((inst_reload)? 1 : 0) << 29;
+ cmd_word |= (inst_samps)? stream_cmd.num_samps : ((inst_chain)? 1 : 0);
+
+ //issue the stream command
+ _iface->poke32(REG_RX_CTRL_STREAM_CMD, cmd_word);
+ _iface->poke32(REG_RX_CTRL_TIME_SECS, boost::uint32_t(stream_cmd.time_spec.get_full_secs()));
+ _iface->poke32(REG_RX_CTRL_TIME_TICKS, stream_cmd.time_spec.get_tick_count(_tick_rate)); //latches the command
+ }
+
+ void set_mux(const std::string &mode){
+ static const uhd::dict<std::string, boost::uint32_t> mode_to_mux = boost::assign::map_list_of
+ ("iq", 0)
+ ("qi", FLAG_DSP_RX_MUX_SWAP_IQ)
+ ("i", FLAG_DSP_RX_MUX_REAL_MODE)
+ ("q", FLAG_DSP_RX_MUX_SWAP_IQ | FLAG_DSP_RX_MUX_REAL_MODE)
+ ;
+ _iface->poke32(REG_DSP_RX_MUX, mode_to_mux[mode]);
+ }
+
+ void set_tick_rate(const double rate){
+ _tick_rate = rate;
+ }
+
+ double set_host_rate(const double rate){
+ int decim = boost::math::iround(_tick_rate/rate);
+
+ //determine which half-band filters are activated
+ int hb0 = 0, hb1 = 0;
+ if (decim % 2 == 0){
+ hb0 = 1;
+ decim /= 2;
+ }
+ if (decim % 2 == 0){
+ hb1 = 1;
+ decim /= 2;
+ }
+
+ _iface->poke32(REG_DSP_RX_DECIM, (hb1 << 9) | (hb0 << 8) | (decim & 0xff));
+
+ return _tick_rate/decim;
+ }
+
+ double set_freq(const double freq_){
+ //correct for outside of rate (wrap around)
+ double freq = std::fmod(freq_, _tick_rate);
+ if (std::abs(freq) > _tick_rate/2.0)
+ freq -= boost::math::sign(freq)*_tick_rate;
+
+ //calculate the freq register word (signed)
+ UHD_ASSERT_THROW(std::abs(freq) <= _tick_rate/2.0);
+ static const double scale_factor = std::pow(2.0, 32);
+ const boost::int32_t freq_word = boost::int32_t(boost::math::round((freq / _tick_rate) * scale_factor));
+
+ //update the actual frequency
+ const double actual_freq = (double(freq_word) / scale_factor) * _tick_rate;
+
+ _iface->poke32(REG_DSP_RX_FREQ, boost::uint32_t(freq_word));
+
+ return actual_freq;
+ }
+
+ void handle_overflow(void){
+ if (_continuous_streaming) issue_stream_command(stream_cmd_t::STREAM_MODE_START_CONTINUOUS);
+ }
+
+private:
+ wb_iface::sptr _iface;
+ const size_t _dsp_base, _ctrl_base;
+ double _tick_rate;
+ bool _continuous_streaming;
+};
+
+rx_dsp_core_200::sptr rx_dsp_core_200::make(wb_iface::sptr iface, const size_t dsp_base, const size_t ctrl_base, const boost::uint32_t sid, const size_t nsamps){
+ return sptr(new rx_dsp_core_200_impl(iface, dsp_base, ctrl_base, sid, nsamps));
+}
diff --git a/host/lib/usrp/cores/rx_dsp_core_200.hpp b/host/lib/usrp/cores/rx_dsp_core_200.hpp
new file mode 100644
index 000000000..dbd7df912
--- /dev/null
+++ b/host/lib/usrp/cores/rx_dsp_core_200.hpp
@@ -0,0 +1,51 @@
+//
+// 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/>.
+//
+
+#ifndef INCLUDED_LIBUHD_USRP_RX_DSP_CORE_200_HPP
+#define INCLUDED_LIBUHD_USRP_RX_DSP_CORE_200_HPP
+
+#include <uhd/config.hpp>
+#include <boost/utility.hpp>
+#include <boost/shared_ptr.hpp>
+#include <uhd/types/stream_cmd.hpp>
+#include "wb_iface.hpp"
+
+class rx_dsp_core_200 : boost::noncopyable{
+public:
+ typedef boost::shared_ptr<rx_dsp_core_200> sptr;
+
+ sptr make(
+ wb_iface::sptr iface,
+ const size_t dsp_base, const size_t ctrl_base,
+ const boost::uint32_t sid, const size_t nsamps
+ );
+
+ virtual void issue_stream_command(const uhd::stream_cmd_t &stream_cmd) = 0;
+
+ virtual void set_mux(const std::string &mode) = 0;
+
+ virtual void set_tick_rate(const double rate) = 0;
+
+ virtual double set_host_rate(const double rate) = 0;
+
+ virtual double set_freq(const double freq) = 0;
+
+ virtual void handle_overflow(void) = 0;
+
+};
+
+#endif /* INCLUDED_LIBUHD_USRP_RX_DSP_CORE_200_HPP */
diff --git a/host/lib/usrp/cores/rx_frontend_core_200.cpp b/host/lib/usrp/cores/rx_frontend_core_200.cpp
new file mode 100644
index 000000000..28e57a13b
--- /dev/null
+++ b/host/lib/usrp/cores/rx_frontend_core_200.cpp
@@ -0,0 +1,28 @@
+//
+// 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/>.
+//
+
+/*
+ void set_mux(const std::string &mode){
+ static const uhd::dict<std::string, boost::uint32_t> mode_to_mux = boost::assign::map_list_of
+ ("iq", (0x1 << 4) | (0x0 << 0)) //DAC0Q=DUC0Q, DAC0I=DUC0I
+ ("qi", (0x0 << 4) | (0x1 << 0)) //DAC0Q=DUC0I, DAC0I=DUC0Q
+ ("i", (0xf << 4) | (0x0 << 0)) //DAC0Q=ZERO, DAC0I=DUC0I
+ ("q", (0x0 << 4) | (0xf << 0)) //DAC0Q=DUC0I, DAC0I=ZERO
+ ;
+ _iface->poke32(, mode_to_mux[mode]);
+ }
+*/
diff --git a/host/lib/usrp/cores/rx_frontend_core_200.hpp b/host/lib/usrp/cores/rx_frontend_core_200.hpp
new file mode 100644
index 000000000..c339a3a94
--- /dev/null
+++ b/host/lib/usrp/cores/rx_frontend_core_200.hpp
@@ -0,0 +1,16 @@
+//
+// 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/>.
+//
diff --git a/host/lib/usrp/cores/tx_dsp_core_200.cpp b/host/lib/usrp/cores/tx_dsp_core_200.cpp
new file mode 100644
index 000000000..c7e18a8a6
--- /dev/null
+++ b/host/lib/usrp/cores/tx_dsp_core_200.cpp
@@ -0,0 +1,123 @@
+//
+// 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 "tx_dsp_core_200.hpp"
+#include <uhd/types/dict.hpp>
+#include <uhd/exception.hpp>
+#include <boost/assign/list_of.hpp>
+#include <boost/math/special_functions/round.hpp>
+#include <boost/math/special_functions/sign.hpp>
+#include <algorithm>
+#include <cmath>
+
+#define REG_DSP_TX_FREQ _dsp_base + 0
+#define REG_DSP_TX_SCALE_IQ _dsp_base + 1
+#define REG_DSP_TX_INTERP _dsp_base + 2
+
+#define REG_TX_CTRL_NUM_CHAN _ctrl_base + 0
+#define REG_TX_CTRL_CLEAR_STATE _ctrl_base + 1
+#define REG_TX_CTRL_REPORT_SID _ctrl_base + 2
+#define REG_TX_CTRL_POLICY _ctrl_base + 3
+#define REG_TX_CTRL_CYCLES_PER_UP _ctrl_base + 4
+#define REG_TX_CTRL_PACKETS_PER_UP _ctrl_base + 5
+
+#define FLAG_TX_CTRL_POLICY_WAIT (0x1 << 0)
+#define FLAG_TX_CTRL_POLICY_NEXT_PACKET (0x1 << 1)
+#define FLAG_TX_CTRL_POLICY_NEXT_BURST (0x1 << 2)
+
+//enable flag for registers: cycles and packets per update packet
+#define FLAG_TX_CTRL_UP_ENB (1ul << 31)
+
+template <class T> T ceil_log2(T num){
+ return std::ceil(std::log(num)/std::log(T(2)));
+}
+
+using namespace uhd;
+
+class tx_dsp_core_200_impl : public tx_dsp_core_200{
+public:
+ tx_dsp_core_200_impl(
+ wb_iface::sptr iface,
+ const size_t dsp_base, const size_t ctrl_base,
+ const boost::uint32_t sid
+ ):
+ _iface(iface), _dsp_base(dsp_base), _ctrl_base(ctrl_base)
+ {
+ //init the tx control registers
+ _iface->poke32(REG_TX_CTRL_CLEAR_STATE, 1); //reset
+ _iface->poke32(REG_TX_CTRL_NUM_CHAN, 0); //1 channel
+ _iface->poke32(REG_TX_CTRL_REPORT_SID, sid);
+ _iface->poke32(REG_TX_CTRL_POLICY, FLAG_TX_CTRL_POLICY_NEXT_PACKET);
+ }
+
+ void set_tick_rate(const double rate){
+ _tick_rate = rate;
+ }
+
+ double set_host_rate(const double rate){
+ int interp = boost::math::iround(_tick_rate/rate);
+
+ //determine which half-band filters are activated
+ int hb0 = 0, hb1 = 0;
+ if (interp % 2 == 0){
+ hb0 = 1;
+ interp /= 2;
+ }
+ if (interp % 2 == 0){
+ hb1 = 1;
+ interp /= 2;
+ }
+
+ _iface->poke32(REG_DSP_TX_INTERP, (hb1 << 9) | (hb0 << 8) | (interp & 0xff));
+
+ // Calculate CIC interpolation (i.e., without halfband interpolators)
+ // Calculate closest multiplier constant to reverse gain absent scale multipliers
+ double rate_cubed = std::pow(double(interp & 0xff), 3);
+ const boost::int16_t scale = boost::math::iround((4096*std::pow(2, ceil_log2(rate_cubed)))/(1.65*rate_cubed));
+ _iface->poke32(REG_DSP_TX_SCALE_IQ, (boost::uint32_t(scale) << 16) | (boost::uint32_t(scale) << 0));
+
+ return _tick_rate/interp;
+ }
+
+ double set_freq(const double freq_){
+ //correct for outside of rate (wrap around)
+ double freq = std::fmod(freq_, _tick_rate);
+ if (std::abs(freq) > _tick_rate/2.0)
+ freq -= boost::math::sign(freq)*_tick_rate;
+
+ //calculate the freq register word (signed)
+ UHD_ASSERT_THROW(std::abs(freq) <= _tick_rate/2.0);
+ static const double scale_factor = std::pow(2.0, 32);
+ const boost::int32_t freq_word = boost::int32_t(boost::math::round((freq / _tick_rate) * scale_factor));
+
+ //update the actual frequency
+ const double actual_freq = (double(freq_word) / scale_factor) * _tick_rate;
+
+ _iface->poke32(REG_DSP_TX_FREQ, boost::uint32_t(freq_word));
+
+ return actual_freq;
+ }
+
+private:
+ wb_iface::sptr _iface;
+ const size_t _dsp_base, _ctrl_base;
+ double _tick_rate;
+};
+
+tx_dsp_core_200::sptr tx_dsp_core_200::make(wb_iface::sptr iface, const size_t dsp_base, const size_t ctrl_base, const boost::uint32_t sid){
+ return sptr(new tx_dsp_core_200_impl(iface, dsp_base, ctrl_base, sid));
+}
diff --git a/host/lib/usrp/cores/tx_dsp_core_200.hpp b/host/lib/usrp/cores/tx_dsp_core_200.hpp
new file mode 100644
index 000000000..3176d495f
--- /dev/null
+++ b/host/lib/usrp/cores/tx_dsp_core_200.hpp
@@ -0,0 +1,44 @@
+//
+// 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/>.
+//
+
+#ifndef INCLUDED_LIBUHD_USRP_TX_DSP_CORE_200_HPP
+#define INCLUDED_LIBUHD_USRP_TX_DSP_CORE_200_HPP
+
+#include <uhd/config.hpp>
+#include <boost/utility.hpp>
+#include <boost/shared_ptr.hpp>
+#include "wb_iface.hpp"
+
+class tx_dsp_core_200 : boost::noncopyable{
+public:
+ typedef boost::shared_ptr<tx_dsp_core_200> sptr;
+
+ sptr make(
+ wb_iface::sptr iface,
+ const size_t dsp_base, const size_t ctrl_base,
+ const boost::uint32_t sid
+ );
+
+ virtual void set_tick_rate(const double rate) = 0;
+
+ virtual double set_host_rate(const double rate) = 0;
+
+ virtual double set_freq(const double freq) = 0;
+
+};
+
+#endif /* INCLUDED_LIBUHD_USRP_TX_DSP_CORE_200_HPP */
diff --git a/host/lib/usrp/cores/tx_frontend_core_200.cpp b/host/lib/usrp/cores/tx_frontend_core_200.cpp
new file mode 100644
index 000000000..c339a3a94
--- /dev/null
+++ b/host/lib/usrp/cores/tx_frontend_core_200.cpp
@@ -0,0 +1,16 @@
+//
+// 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/>.
+//
diff --git a/host/lib/usrp/cores/tx_frontend_core_200.hpp b/host/lib/usrp/cores/tx_frontend_core_200.hpp
new file mode 100644
index 000000000..c339a3a94
--- /dev/null
+++ b/host/lib/usrp/cores/tx_frontend_core_200.hpp
@@ -0,0 +1,16 @@
+//
+// 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/>.
+//