Move all license headers to SPDX format.

39 files changed, 253 insertions, 682 deletions

diff --git a/host/lib/transport/CMakeLists.txt b/host/lib/transport/CMakeLists.txt
index c8fd16ef3..b712e395d 100644
--- a/host/lib/transport/CMakeLists.txt
+++ b/host/lib/transport/CMakeLists.txt
@@ -1,18 +1,7 @@
 #
 # Copyright 2010-2013,2015 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/>.
+# SPDX-License-Identifier: GPL-3.0
 #
 
 ########################################################################
diff --git a/host/lib/transport/buffer_pool.cpp b/host/lib/transport/buffer_pool.cpp
index 47e30ee44..e3415ec4d 100644
--- a/host/lib/transport/buffer_pool.cpp
+++ b/host/lib/transport/buffer_pool.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2011,2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/buffer_pool.hpp>
diff --git a/host/lib/transport/chdr.cpp b/host/lib/transport/chdr.cpp
index 0c4643ba7..5e552320e 100644
--- a/host/lib/transport/chdr.cpp
+++ b/host/lib/transport/chdr.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/chdr.hpp>
diff --git a/host/lib/transport/gen_vrt_if_packet.py b/host/lib/transport/gen_vrt_if_packet.py
index bdef39881..f5c6785c1 100644
--- a/host/lib/transport/gen_vrt_if_packet.py
+++ b/host/lib/transport/gen_vrt_if_packet.py
@@ -2,18 +2,7 @@
 #
 # Copyright 2010-2013,2015 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/>.
+# SPDX-License-Identifier: GPL-3.0
 #
 
 """
diff --git a/host/lib/transport/if_addrs.cpp b/host/lib/transport/if_addrs.cpp
index 37b41f303..8a184648e 100644
--- a/host/lib/transport/if_addrs.cpp
+++ b/host/lib/transport/if_addrs.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2011 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/if_addrs.hpp>
diff --git a/host/lib/transport/libusb1_base.cpp b/host/lib/transport/libusb1_base.cpp
index 24c9e3471..9a9aab7e3 100644
--- a/host/lib/transport/libusb1_base.cpp
+++ b/host/lib/transport/libusb1_base.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2015 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "libusb1_base.hpp"
diff --git a/host/lib/transport/libusb1_base.hpp b/host/lib/transport/libusb1_base.hpp
index 6d104bc75..a0e5c7e12 100644
--- a/host/lib/transport/libusb1_base.hpp
+++ b/host/lib/transport/libusb1_base.hpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #ifndef INCLUDED_LIBUHD_TRANSPORT_LIBUSB_HPP
diff --git a/host/lib/transport/libusb1_control.cpp b/host/lib/transport/libusb1_control.cpp
index 2bfffc0a3..a0e8d02d2 100644
--- a/host/lib/transport/libusb1_control.cpp
+++ b/host/lib/transport/libusb1_control.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010,2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "libusb1_base.hpp"
diff --git a/host/lib/transport/libusb1_zero_copy.cpp b/host/lib/transport/libusb1_zero_copy.cpp
index 39666af94..98280488b 100644
--- a/host/lib/transport/libusb1_zero_copy.cpp
+++ b/host/lib/transport/libusb1_zero_copy.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "libusb1_base.hpp"
diff --git a/host/lib/transport/muxed_zero_copy_if.cpp b/host/lib/transport/muxed_zero_copy_if.cpp
index 37bea7355..411cce537 100644
--- a/host/lib/transport/muxed_zero_copy_if.cpp
+++ b/host/lib/transport/muxed_zero_copy_if.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2016 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/muxed_zero_copy_if.hpp>
diff --git a/host/lib/transport/nirio/CMakeLists.txt b/host/lib/transport/nirio/CMakeLists.txt
index 99beda056..c759166f3 100644
--- a/host/lib/transport/nirio/CMakeLists.txt
+++ b/host/lib/transport/nirio/CMakeLists.txt
@@ -1,18 +1,7 @@
 #
 # Copyright 2013-2014 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/>.
+# SPDX-License-Identifier: GPL-3.0
 #
 
 ########################################################################
diff --git a/host/lib/transport/nirio/lvbitx/CMakeLists.txt b/host/lib/transport/nirio/lvbitx/CMakeLists.txt
index 5741a12f8..99c1a194e 100644
--- a/host/lib/transport/nirio/lvbitx/CMakeLists.txt
+++ b/host/lib/transport/nirio/lvbitx/CMakeLists.txt
@@ -1,18 +1,7 @@
 #
 # Copyright 2013,2015 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/>.
+# SPDX-License-Identifier: GPL-3.0
 #
 
 MACRO(LIBUHD_LVBITX_GEN_SOURCE_AND_BITSTREAM lvbitx binfile)
diff --git a/host/lib/transport/nirio/lvbitx/process-lvbitx.py b/host/lib/transport/nirio/lvbitx/process-lvbitx.py
index 8b06cb01c..09af4606b 100755
--- a/host/lib/transport/nirio/lvbitx/process-lvbitx.py
+++ b/host/lib/transport/nirio/lvbitx/process-lvbitx.py
@@ -2,18 +2,7 @@
 #
 # Copyright 2013-2015 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/>.
+# SPDX-License-Identifier: GPL-3.0
 #
 
 from xml.etree import ElementTree
diff --git a/host/lib/transport/nirio/nifpga_lvbitx.cpp b/host/lib/transport/nirio/nifpga_lvbitx.cpp
index 8135a4d01..f018446aa 100644
--- a/host/lib/transport/nirio/nifpga_lvbitx.cpp
+++ b/host/lib/transport/nirio/nifpga_lvbitx.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013-2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/nifpga_lvbitx.h>
diff --git a/host/lib/transport/nirio/nirio_driver_iface_linux.cpp b/host/lib/transport/nirio/nirio_driver_iface_linux.cpp
index 4d983de17..680fc49fd 100644
--- a/host/lib/transport/nirio/nirio_driver_iface_linux.cpp
+++ b/host/lib/transport/nirio/nirio_driver_iface_linux.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/nirio_driver_iface.h>
diff --git a/host/lib/transport/nirio/nirio_driver_iface_unsupported.cpp b/host/lib/transport/nirio/nirio_driver_iface_unsupported.cpp
index ba0febe20..f212867b5 100644
--- a/host/lib/transport/nirio/nirio_driver_iface_unsupported.cpp
+++ b/host/lib/transport/nirio/nirio_driver_iface_unsupported.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013,2015 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 #include <uhd/transport/nirio/nirio_driver_iface.h>
 
diff --git a/host/lib/transport/nirio/nirio_driver_iface_win.cpp b/host/lib/transport/nirio/nirio_driver_iface_win.cpp
index c8484e953..9d213a4e1 100644
--- a/host/lib/transport/nirio/nirio_driver_iface_win.cpp
+++ b/host/lib/transport/nirio/nirio_driver_iface_win.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013,2015-2016 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/nirio_driver_iface.h>
diff --git a/host/lib/transport/nirio/nirio_resource_manager.cpp b/host/lib/transport/nirio/nirio_resource_manager.cpp
index d62f5c40d..3eb9d1665 100644
--- a/host/lib/transport/nirio/nirio_resource_manager.cpp
+++ b/host/lib/transport/nirio/nirio_resource_manager.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/nirio_resource_manager.h>
diff --git a/host/lib/transport/nirio/niriok_proxy.cpp b/host/lib/transport/nirio/niriok_proxy.cpp
index 0cc13efb8..7eb211d15 100644
--- a/host/lib/transport/nirio/niriok_proxy.cpp
+++ b/host/lib/transport/nirio/niriok_proxy.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013-2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/niriok_proxy.h>
diff --git a/host/lib/transport/nirio/niriok_proxy_impl_v1.cpp b/host/lib/transport/nirio/niriok_proxy_impl_v1.cpp
index dbe9e4abd..b851827c7 100644
--- a/host/lib/transport/nirio/niriok_proxy_impl_v1.cpp
+++ b/host/lib/transport/nirio/niriok_proxy_impl_v1.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013-2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/niriok_proxy_impl_v1.h>
diff --git a/host/lib/transport/nirio/niriok_proxy_impl_v2.cpp b/host/lib/transport/nirio/niriok_proxy_impl_v2.cpp
index 4e88b8a6e..4881a9596 100644
--- a/host/lib/transport/nirio/niriok_proxy_impl_v2.cpp
+++ b/host/lib/transport/nirio/niriok_proxy_impl_v2.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013-2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 
diff --git a/host/lib/transport/nirio/niusrprio_session.cpp b/host/lib/transport/nirio/niusrprio_session.cpp
index f1e31572c..8d0c05a8f 100644
--- a/host/lib/transport/nirio/niusrprio_session.cpp
+++ b/host/lib/transport/nirio/niusrprio_session.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 
diff --git a/host/lib/transport/nirio/rpc/CMakeLists.txt b/host/lib/transport/nirio/rpc/CMakeLists.txt
index 02c16d2ff..e5563c928 100644
--- a/host/lib/transport/nirio/rpc/CMakeLists.txt
+++ b/host/lib/transport/nirio/rpc/CMakeLists.txt
@@ -1,18 +1,7 @@
 #
 # Copyright 2013 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/>.
+# SPDX-License-Identifier: GPL-3.0
 #
 
 ########################################################################
diff --git a/host/lib/transport/nirio/rpc/rpc_client.cpp b/host/lib/transport/nirio/rpc/rpc_client.cpp
index 96f98ec20..28cb9d734 100644
--- a/host/lib/transport/nirio/rpc/rpc_client.cpp
+++ b/host/lib/transport/nirio/rpc/rpc_client.cpp
@@ -1,18 +1,7 @@
 ///
 // Copyright 2013,2016 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/rpc/rpc_client.hpp>
diff --git a/host/lib/transport/nirio/rpc/usrprio_rpc_client.cpp b/host/lib/transport/nirio/rpc/usrprio_rpc_client.cpp
index 0e58f161c..77ea539ba 100644
--- a/host/lib/transport/nirio/rpc/usrprio_rpc_client.cpp
+++ b/host/lib/transport/nirio/rpc/usrprio_rpc_client.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio/rpc/usrprio_rpc_client.hpp>
diff --git a/host/lib/transport/nirio/status.cpp b/host/lib/transport/nirio/status.cpp
index f3f8d4cd1..2004063fe 100644
--- a/host/lib/transport/nirio/status.cpp
+++ b/host/lib/transport/nirio/status.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 
diff --git a/host/lib/transport/nirio_zero_copy.cpp b/host/lib/transport/nirio_zero_copy.cpp
index 87d44865a..02c058ee6 100644
--- a/host/lib/transport/nirio_zero_copy.cpp
+++ b/host/lib/transport/nirio_zero_copy.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2013-2015 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/nirio_zero_copy.hpp>
diff --git a/host/lib/transport/super_recv_packet_handler.hpp b/host/lib/transport/super_recv_packet_handler.hpp
index 4abc73398..df56d7ed6 100644
--- a/host/lib/transport/super_recv_packet_handler.hpp
+++ b/host/lib/transport/super_recv_packet_handler.hpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2011-2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #ifndef INCLUDED_LIBUHD_TRANSPORT_SUPER_RECV_PACKET_HANDLER_HPP
diff --git a/host/lib/transport/super_send_packet_handler.hpp b/host/lib/transport/super_send_packet_handler.hpp
index 75ba7260b..4b2ae1f22 100644
--- a/host/lib/transport/super_send_packet_handler.hpp
+++ b/host/lib/transport/super_send_packet_handler.hpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2011-2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #ifndef INCLUDED_LIBUHD_TRANSPORT_SUPER_SEND_PACKET_HANDLER_HPP
diff --git a/host/lib/transport/tcp_zero_copy.cpp b/host/lib/transport/tcp_zero_copy.cpp
index 4c434527c..50ffaf48d 100644
--- a/host/lib/transport/tcp_zero_copy.cpp
+++ b/host/lib/transport/tcp_zero_copy.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "udp_common.hpp"
diff --git a/host/lib/transport/udp_common.hpp b/host/lib/transport/udp_common.hpp
index d6e73cc5f..4c8ca9f96 100644
--- a/host/lib/transport/udp_common.hpp
+++ b/host/lib/transport/udp_common.hpp
@@ -1,18 +1,7 @@
 //
 // 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #ifndef INCLUDED_LIBUHD_TRANSPORT_VRT_PACKET_HANDLER_HPP
diff --git a/host/lib/transport/udp_simple.cpp b/host/lib/transport/udp_simple.cpp
index c469e5b1b..5f1eb66b9 100644
--- a/host/lib/transport/udp_simple.cpp
+++ b/host/lib/transport/udp_simple.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2011,2014 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "udp_common.hpp"
diff --git a/host/lib/transport/udp_wsa_zero_copy.cpp b/host/lib/transport/udp_wsa_zero_copy.cpp
index 4d054f2e0..52bbd9728 100644
--- a/host/lib/transport/udp_wsa_zero_copy.cpp
+++ b/host/lib/transport/udp_wsa_zero_copy.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2011 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "udp_common.hpp"
diff --git a/host/lib/transport/udp_zero_copy.cpp b/host/lib/transport/udp_zero_copy.cpp
index 9a80fafd1..aa07d588b 100644
--- a/host/lib/transport/udp_zero_copy.cpp
+++ b/host/lib/transport/udp_zero_copy.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "udp_common.hpp"
diff --git a/host/lib/transport/usb_dummy_impl.cpp b/host/lib/transport/usb_dummy_impl.cpp
index 29f813963..e0241cf71 100644
--- a/host/lib/transport/usb_dummy_impl.cpp
+++ b/host/lib/transport/usb_dummy_impl.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2011 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/usb_device_handle.hpp>
diff --git a/host/lib/transport/xport_benchmarker.cpp b/host/lib/transport/xport_benchmarker.cpp
index 7157c1ae9..b9cf1944a 100644
--- a/host/lib/transport/xport_benchmarker.cpp
+++ b/host/lib/transport/xport_benchmarker.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include "xport_benchmarker.hpp"
diff --git a/host/lib/transport/xport_benchmarker.hpp b/host/lib/transport/xport_benchmarker.hpp
index ffafbea5a..87c88ca47 100644
--- a/host/lib/transport/xport_benchmarker.hpp
+++ b/host/lib/transport/xport_benchmarker.hpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2010-2013 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #ifndef INCLUDED_LIBUHD_XPORT_BENCHMARKER_HPP
diff --git a/host/lib/transport/zero_copy_flow_ctrl.cpp b/host/lib/transport/zero_copy_flow_ctrl.cpp
index ef8f5c9d1..beb992da4 100644
--- a/host/lib/transport/zero_copy_flow_ctrl.cpp
+++ b/host/lib/transport/zero_copy_flow_ctrl.cpp
@@ -1,226 +1,215 @@
-//

-// Copyright 2017 Ettus Research

-//

-// 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 <uhd/transport/zero_copy_flow_ctrl.hpp>

-#include <uhd/transport/bounded_buffer.hpp>

-#include <uhd/transport/buffer_pool.hpp>

-#include <uhd/utils/log.hpp>

-#include <uhd/utils/safe_call.hpp>

-#include <boost/format.hpp>

-#include <boost/make_shared.hpp>

-#include <boost/thread/mutex.hpp>

-#include <boost/thread/thread.hpp>

-#include <boost/bind.hpp>

-

-using namespace uhd;

-using namespace uhd::transport;

-

-typedef bounded_buffer<managed_send_buffer::sptr> bounded_buffer_t;

-

-class zero_copy_flow_ctrl_msb : public managed_send_buffer

-{

-public:

-    zero_copy_flow_ctrl_msb(

-        flow_ctrl_func flow_ctrl

-    ) :

-        _mb(nullptr),

-        _flow_ctrl(flow_ctrl)

-    {

-        /* NOP */

-    }

-

-    ~zero_copy_flow_ctrl_msb()

-    {

-        /* NOP */

-    }

-

-    void release()

-    {

-        if (_mb)

-        {

-            _mb->commit(size());

-            while (_flow_ctrl and not _flow_ctrl(_mb)) {}

-            _mb.reset();

-        }

-    }

-

-    UHD_INLINE sptr get(sptr &mb)

-    {

-        _mb = mb;

-        return make(this, _mb->cast<void *>(), _mb->size());

-    }

-

-private:

-    sptr _mb;

-    flow_ctrl_func _flow_ctrl;

-};

-

-class zero_copy_flow_ctrl_mrb : public managed_recv_buffer

-{

-public:

-    zero_copy_flow_ctrl_mrb(

-        flow_ctrl_func flow_ctrl

-    ) :

-        _mb(nullptr),

-        _flow_ctrl(flow_ctrl)

-    {

-        /* NOP */

-    }

-

-    ~zero_copy_flow_ctrl_mrb()

-    {

-        /* NOP */

-    }

-

-    void release()

-    {

-        if (_mb)

-        {

-            _mb->commit(size());

-            while (_flow_ctrl and not _flow_ctrl(_mb)) {}

-            _mb.reset();

-        }

-    }

-

-    UHD_INLINE sptr get(sptr &mb)

-    {

-        _mb = mb;

-        return make(this, _mb->cast<void *>(), _mb->size());

-    }

-

-private:

-    sptr _mb;

-    flow_ctrl_func _flow_ctrl;

-};

-

-/***********************************************************************

- * Zero copy offload transport:

- * An intermediate transport that utilizes threading to free

- * the main thread from any receive work.

- **********************************************************************/

-class zero_copy_flow_ctrl_impl : public zero_copy_flow_ctrl {

-public:

-    typedef boost::shared_ptr<zero_copy_flow_ctrl_impl> sptr;

-

-    zero_copy_flow_ctrl_impl(zero_copy_if::sptr transport,

-        flow_ctrl_func send_flow_ctrl,

-        flow_ctrl_func recv_flow_ctrl) :

-        _transport(transport),

-        _send_buffers(transport->get_num_send_frames()),

-        _recv_buffers(transport->get_num_recv_frames()),

-        _send_buff_index(0),

-        _recv_buff_index(0),

-        _send_flow_ctrl(send_flow_ctrl),

-        _recv_flow_ctrl(recv_flow_ctrl)

-    {

-        UHD_LOG_TRACE("TRANSPORT", "Created zero_copy_flow_ctrl");

-

-        for (size_t i = 0; i < transport->get_num_send_frames(); i++)

-        {

-            _send_buffers[i] = boost::make_shared<zero_copy_flow_ctrl_msb>(_send_flow_ctrl);

-        }

-        for (size_t i = 0; i < transport->get_num_recv_frames(); i++)

-        {

-            _recv_buffers[i] = boost::make_shared<zero_copy_flow_ctrl_mrb>(_recv_flow_ctrl);

-        }

-    }

-

-    ~zero_copy_flow_ctrl_impl()

-    {

-    }

-

-    /*******************************************************************

-     * Receive implementation:

-     * Pop the receive buffer pointer from the underlying transport

-     ******************************************************************/

-    UHD_INLINE managed_recv_buffer::sptr get_recv_buff(double timeout)

-    {

-        managed_recv_buffer::sptr ptr;

-        managed_recv_buffer::sptr buff = _transport->get_recv_buff(timeout);

-        if (buff)

-        {

-            boost::shared_ptr<zero_copy_flow_ctrl_mrb> mb = _recv_buffers[_recv_buff_index++];

-            _recv_buff_index %= _recv_buffers.size();

-            ptr = mb->get(buff);

-        }

-        return ptr;

-    }

-

-    UHD_INLINE size_t get_num_recv_frames() const

-    {

-        return _transport->get_num_recv_frames();

-    }

-

-    UHD_INLINE size_t get_recv_frame_size() const

-    {

-        return _transport->get_recv_frame_size();

-    }

-

-    /*******************************************************************

-     * Send implementation:

-     * Pass the send buffer pointer from the underlying transport

-     ******************************************************************/

-    managed_send_buffer::sptr get_send_buff(double timeout)

-    {

-        managed_send_buffer::sptr ptr;

-        managed_send_buffer::sptr buff = _transport->get_send_buff(timeout);

-        if (buff)

-        {

-            boost::shared_ptr<zero_copy_flow_ctrl_msb> mb = _send_buffers[_send_buff_index++];

-            _send_buff_index %= _send_buffers.size();

-            ptr = mb->get(buff);

-        }

-        return ptr;

-    }

-

-    UHD_INLINE size_t get_num_send_frames() const

-    {

-        return _transport->get_num_send_frames();

-    }

-

-    UHD_INLINE size_t get_send_frame_size() const

-    {

-        return _transport->get_send_frame_size();

-    }

-

-private:

-    // The underlying transport

-    zero_copy_if::sptr _transport;

-

-    // buffers

-    std::vector< boost::shared_ptr<zero_copy_flow_ctrl_msb> > _send_buffers;

-    std::vector< boost::shared_ptr<zero_copy_flow_ctrl_mrb> > _recv_buffers;

-    size_t _send_buff_index;

-    size_t _recv_buff_index;

-

-    // Flow control functions

-    flow_ctrl_func _send_flow_ctrl;

-    flow_ctrl_func _recv_flow_ctrl;

-};

-

-zero_copy_flow_ctrl::sptr zero_copy_flow_ctrl::make(

-        zero_copy_if::sptr transport,

-        flow_ctrl_func send_flow_ctrl,

-        flow_ctrl_func recv_flow_ctrl

-)

-{

-    zero_copy_flow_ctrl_impl::sptr zero_copy_flow_ctrl(

-        new zero_copy_flow_ctrl_impl(transport, send_flow_ctrl, recv_flow_ctrl)

-    );

-

-    return zero_copy_flow_ctrl;

-}

+//
+// Copyright 2017 Ettus Research
+//
+// SPDX-License-Identifier: GPL-3.0
+//
+
+#include <uhd/transport/zero_copy_flow_ctrl.hpp>
+#include <uhd/transport/bounded_buffer.hpp>
+#include <uhd/transport/buffer_pool.hpp>
+#include <uhd/utils/log.hpp>
+#include <uhd/utils/safe_call.hpp>
+#include <boost/format.hpp>
+#include <boost/make_shared.hpp>
+#include <boost/thread/mutex.hpp>
+#include <boost/thread/thread.hpp>
+#include <boost/bind.hpp>
+
+using namespace uhd;
+using namespace uhd::transport;
+
+typedef bounded_buffer<managed_send_buffer::sptr> bounded_buffer_t;
+
+class zero_copy_flow_ctrl_msb : public managed_send_buffer
+{
+public:
+    zero_copy_flow_ctrl_msb(
+        flow_ctrl_func flow_ctrl
+    ) :
+        _mb(nullptr),
+        _flow_ctrl(flow_ctrl)
+    {
+        /* NOP */
+    }
+
+    ~zero_copy_flow_ctrl_msb()
+    {
+        /* NOP */
+    }
+
+    void release()
+    {
+        if (_mb)
+        {
+            _mb->commit(size());
+            while (_flow_ctrl and not _flow_ctrl(_mb)) {}
+            _mb.reset();
+        }
+    }
+
+    UHD_INLINE sptr get(sptr &mb)
+    {
+        _mb = mb;
+        return make(this, _mb->cast<void *>(), _mb->size());
+    }
+
+private:
+    sptr _mb;
+    flow_ctrl_func _flow_ctrl;
+};
+
+class zero_copy_flow_ctrl_mrb : public managed_recv_buffer
+{
+public:
+    zero_copy_flow_ctrl_mrb(
+        flow_ctrl_func flow_ctrl
+    ) :
+        _mb(nullptr),
+        _flow_ctrl(flow_ctrl)
+    {
+        /* NOP */
+    }
+
+    ~zero_copy_flow_ctrl_mrb()
+    {
+        /* NOP */
+    }
+
+    void release()
+    {
+        if (_mb)
+        {
+            _mb->commit(size());
+            while (_flow_ctrl and not _flow_ctrl(_mb)) {}
+            _mb.reset();
+        }
+    }
+
+    UHD_INLINE sptr get(sptr &mb)
+    {
+        _mb = mb;
+        return make(this, _mb->cast<void *>(), _mb->size());
+    }
+
+private:
+    sptr _mb;
+    flow_ctrl_func _flow_ctrl;
+};
+
+/***********************************************************************
+ * Zero copy offload transport:
+ * An intermediate transport that utilizes threading to free
+ * the main thread from any receive work.
+ **********************************************************************/
+class zero_copy_flow_ctrl_impl : public zero_copy_flow_ctrl {
+public:
+    typedef boost::shared_ptr<zero_copy_flow_ctrl_impl> sptr;
+
+    zero_copy_flow_ctrl_impl(zero_copy_if::sptr transport,
+        flow_ctrl_func send_flow_ctrl,
+        flow_ctrl_func recv_flow_ctrl) :
+        _transport(transport),
+        _send_buffers(transport->get_num_send_frames()),
+        _recv_buffers(transport->get_num_recv_frames()),
+        _send_buff_index(0),
+        _recv_buff_index(0),
+        _send_flow_ctrl(send_flow_ctrl),
+        _recv_flow_ctrl(recv_flow_ctrl)
+    {
+        UHD_LOG_TRACE("TRANSPORT", "Created zero_copy_flow_ctrl");
+
+        for (size_t i = 0; i < transport->get_num_send_frames(); i++)
+        {
+            _send_buffers[i] = boost::make_shared<zero_copy_flow_ctrl_msb>(_send_flow_ctrl);
+        }
+        for (size_t i = 0; i < transport->get_num_recv_frames(); i++)
+        {
+            _recv_buffers[i] = boost::make_shared<zero_copy_flow_ctrl_mrb>(_recv_flow_ctrl);
+        }
+    }
+
+    ~zero_copy_flow_ctrl_impl()
+    {
+    }
+
+    /*******************************************************************
+     * Receive implementation:
+     * Pop the receive buffer pointer from the underlying transport
+     ******************************************************************/
+    UHD_INLINE managed_recv_buffer::sptr get_recv_buff(double timeout)
+    {
+        managed_recv_buffer::sptr ptr;
+        managed_recv_buffer::sptr buff = _transport->get_recv_buff(timeout);
+        if (buff)
+        {
+            boost::shared_ptr<zero_copy_flow_ctrl_mrb> mb = _recv_buffers[_recv_buff_index++];
+            _recv_buff_index %= _recv_buffers.size();
+            ptr = mb->get(buff);
+        }
+        return ptr;
+    }
+
+    UHD_INLINE size_t get_num_recv_frames() const
+    {
+        return _transport->get_num_recv_frames();
+    }
+
+    UHD_INLINE size_t get_recv_frame_size() const
+    {
+        return _transport->get_recv_frame_size();
+    }
+
+    /*******************************************************************
+     * Send implementation:
+     * Pass the send buffer pointer from the underlying transport
+     ******************************************************************/
+    managed_send_buffer::sptr get_send_buff(double timeout)
+    {
+        managed_send_buffer::sptr ptr;
+        managed_send_buffer::sptr buff = _transport->get_send_buff(timeout);
+        if (buff)
+        {
+            boost::shared_ptr<zero_copy_flow_ctrl_msb> mb = _send_buffers[_send_buff_index++];
+            _send_buff_index %= _send_buffers.size();
+            ptr = mb->get(buff);
+        }
+        return ptr;
+    }
+
+    UHD_INLINE size_t get_num_send_frames() const
+    {
+        return _transport->get_num_send_frames();
+    }
+
+    UHD_INLINE size_t get_send_frame_size() const
+    {
+        return _transport->get_send_frame_size();
+    }
+
+private:
+    // The underlying transport
+    zero_copy_if::sptr _transport;
+
+    // buffers
+    std::vector< boost::shared_ptr<zero_copy_flow_ctrl_msb> > _send_buffers;
+    std::vector< boost::shared_ptr<zero_copy_flow_ctrl_mrb> > _recv_buffers;
+    size_t _send_buff_index;
+    size_t _recv_buff_index;
+
+    // Flow control functions
+    flow_ctrl_func _send_flow_ctrl;
+    flow_ctrl_func _recv_flow_ctrl;
+};
+
+zero_copy_flow_ctrl::sptr zero_copy_flow_ctrl::make(
+        zero_copy_if::sptr transport,
+        flow_ctrl_func send_flow_ctrl,
+        flow_ctrl_func recv_flow_ctrl
+)
+{
+    zero_copy_flow_ctrl_impl::sptr zero_copy_flow_ctrl(
+        new zero_copy_flow_ctrl_impl(transport, send_flow_ctrl, recv_flow_ctrl)
+    );
+
+    return zero_copy_flow_ctrl;
+}
diff --git a/host/lib/transport/zero_copy_recv_offload.cpp b/host/lib/transport/zero_copy_recv_offload.cpp
index e8f75be84..56e5381a2 100644
--- a/host/lib/transport/zero_copy_recv_offload.cpp
+++ b/host/lib/transport/zero_copy_recv_offload.cpp
@@ -1,18 +1,7 @@
 //
 // Copyright 2016 Ettus Research
 //
-// 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/>.
+// SPDX-License-Identifier: GPL-3.0
 //
 
 #include <uhd/transport/zero_copy_recv_offload.hpp>