Added a vrt library to pack and unpack from metadata.

Added a vrt test app that packs and unpacks the data.

1 files changed, 104 insertions, 0 deletions

diff --git a/host/lib/transport/vrt.cpp b/host/lib/transport/vrt.cpp
new file mode 100644
index 000000000..40b26d31f
--- /dev/null
+++ b/host/lib/transport/vrt.cpp
@@ -0,0 +1,104 @@
+//
+// Copyright 2010 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 <uhd/transport/vrt.hpp>
+#include <netinet/in.h>
+#include <stdexcept>
+
+using namespace uhd::transport;
+
+void vrt::pack(
+    const metadata_t &metadata, //input
+    uint32_t *header_buff,      //output
+    size_t &num_header_words32, //output
+    size_t num_payload_words32, //input
+    size_t packet_count         //input
+){
+    uint32_t vrt_hdr_flags = 0;
+    num_header_words32 = 1;
+
+    //load the vrt header and flags
+    if(metadata.has_stream_id){
+        vrt_hdr_flags |= (0x1 << 28); //IF Data packet with Stream Identifier
+        header_buff[num_header_words32++] = htonl(metadata.stream_id);
+    }
+
+    if(metadata.has_time_spec){
+        vrt_hdr_flags |= (0x3 << 22) | (0x1 << 20); //TSI: Other, TSF: Sample Count Timestamp
+        header_buff[num_header_words32++] = htonl(metadata.time_spec.secs);
+        header_buff[num_header_words32++] = htonl(metadata.time_spec.ticks);
+        header_buff[num_header_words32++] = 0; //unused part of fractional seconds
+    }
+
+    vrt_hdr_flags |= (metadata.start_of_burst)? (0x1 << 25) : 0;
+    vrt_hdr_flags |= (metadata.end_of_burst)?   (0x1 << 24) : 0;
+
+    //fill in complete header word
+    header_buff[0] = htonl(vrt_hdr_flags |
+        ((packet_count & 0xf) << 16) |
+        ((num_header_words32 + num_payload_words32) & 0xffff)
+    );
+}
+
+void vrt::unpack(
+    metadata_t &metadata,            //output
+    const uint32_t *header_buff,     //input
+    size_t &num_header_words32,      //output
+    size_t &num_payload_words32,     //output
+    size_t &packet_count             //output
+){
+    //clear the metadata
+    metadata = metadata_t();
+
+    //extract vrt header
+    uint32_t vrt_hdr_word = ntohl(header_buff[0]);
+    size_t packet_words32 = vrt_hdr_word & 0xffff;
+    packet_count = (vrt_hdr_word >> 16) & 0xf;
+
+    //failure cases
+    if (packet_words32 == 0) //FIXME check the packet length before we continue
+        throw std::runtime_error("bad vrt header");
+    if (vrt_hdr_word & (0x7 << 29))
+        throw std::runtime_error("unsupported vrt packet type");
+
+    //parse the header flags
+    num_header_words32 = 1;
+
+    if (vrt_hdr_word & (0x1 << 28)){ //stream id
+        metadata.has_stream_id = true;
+        metadata.stream_id = ntohl(header_buff[num_header_words32++]);
+    }
+
+    if (vrt_hdr_word & (0x1 << 27)){ //class id (we dont use)
+        num_header_words32 += 2;
+    }
+
+    if (vrt_hdr_word & (0x3 << 22)){ //integer time
+        metadata.has_time_spec = true;
+        metadata.time_spec.secs = ntohl(header_buff[num_header_words32++]);
+    }
+
+    if (vrt_hdr_word & (0x3 << 20)){ //fractional time
+        metadata.has_time_spec = true;
+        metadata.time_spec.ticks = ntohl(header_buff[num_header_words32++]);
+        num_header_words32++; //unused part of fractional seconds
+    }
+
+    size_t num_trailer_words32 = (vrt_hdr_word & (0x1 << 26))? 1 : 0;
+
+    num_payload_words32 = packet_words32 - num_header_words32 - num_trailer_words32;
+}