udp: update docs for transport, create common header for wait implementation

Reimplemented simple udp transport with one impl class.
Moved wait for ready/select implementation into common header.
Important note on select, timeval should have usecs < 1 second
or it may error on some platforms. Fixed in this implementation.

1 files changed, 51 insertions, 0 deletions

diff --git a/host/lib/transport/udp_common.hpp b/host/lib/transport/udp_common.hpp
new file mode 100644
index 000000000..44067b5dc
--- /dev/null
+++ b/host/lib/transport/udp_common.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_TRANSPORT_VRT_PACKET_HANDLER_HPP
+#define INCLUDED_LIBUHD_TRANSPORT_VRT_PACKET_HANDLER_HPP
+
+#include <uhd/config.hpp>
+#include <boost/asio.hpp>
+
+namespace uhd{ namespace transport{
+
+    /*!
+     * Wait for the socket to become ready for a receive operation.
+     * \param sock_fd the open socket file descriptor
+     * \param timeout the timeout duration in seconds
+     * \return true when the socket is ready for receive
+     */
+    UHD_INLINE bool wait_for_recv(int sock_fd, double timeout){
+        //setup timeval for timeout
+        timeval tv;
+        //If the tv_usec > 1 second on some platforms, select will
+        //error EINVAL: An invalid timeout interval was specified.
+        tv.tv_sec = int(timeout);
+        tv.tv_usec = int(timeout*1000000)%1000000;
+
+        //setup rset for timeout
+        fd_set rset;
+        FD_ZERO(&rset);
+        FD_SET(sock_fd, &rset);
+
+        //call select with timeout on receive socket
+        return ::select(sock_fd+1, &rset, NULL, NULL, &tv) > 0;
+    }
+
+}} //namespace uhd::transport
+
+#endif /* INCLUDED_LIBUHD_TRANSPORT_VRT_PACKET_HANDLER_HPP */