made python app to generate vrt jump tables, seems to run faster...

2 files changed, 700 insertions, 56 deletions

diff --git a/host/lib/transport/gen_vrt.py b/host/lib/transport/gen_vrt.py
new file mode 100755
index 000000000..918de3ad7
--- /dev/null
+++ b/host/lib/transport/gen_vrt.py
@@ -0,0 +1,206 @@
+#!/usr/bin/env python
+#
+# 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/>.
+#
+
+"""
+The vrt packer/unpacker code generator:
+
+This script will generate the pack and unpack routines that convert
+metatdata into vrt headers and vrt headers into metadata.
+
+The generated code infers jump tables to speed-up the parsing time.
+"""
+
+TMPL_TEXT = """
+#import time
+
+########################################################################
+## setup predicates
+########################################################################
+#set $sid_p = 0b00001
+#set $cid_p = 0b00010
+#set $tsi_p = 0b00100
+#set $tsf_p = 0b01000
+#set $tlr_p = 0b10000
+
+/***********************************************************************
+ * This file was generated by $file on $time.strftime("%c")
+ **********************************************************************/
+
+\#include <uhd/transport/vrt.hpp>
+\#include <boost/asio.hpp> //endianness conversion
+\#include <stdexcept>
+
+using namespace uhd;
+using namespace uhd::transport;
+
+void vrt::pack(
+    const tx_metadata_t &metadata, //input
+    boost::uint32_t *header_buff,  //output
+    size_t &num_header_words32,    //output
+    size_t num_payload_words32,    //input
+    size_t &num_packet_words32,    //output
+    size_t packet_count            //input
+){
+    boost::uint32_t vrt_hdr_flags;
+
+    boost::uint8_t pred = 0;
+    if (metadata.has_stream_id) pred |= $hex($sid_p);
+    if (metadata.has_time_spec) pred |= $hex($tsi_p | $tsf_p);
+
+    switch(pred){
+    #for $pred in range(2**5)
+    case $pred:
+        #set $num_header_words = 1
+        #set $flags = 0
+        ########## Stream ID ##########
+        #if $pred & $sid_p
+            header_buff[$num_header_words] = htonl(metadata.stream_id);
+            #set $num_header_words += 1
+            #set $flags |= (0x1 << 28);
+        #end if
+        ########## Class ID ##########
+        #if $pred & $cid_p
+            header_buff[$num_header_words] = htonl(0);
+            #set $num_header_words += 1
+            header_buff[$num_header_words] = htonl(0);
+            #set $num_header_words += 1
+            #set $flags |= (0x1 << 27);
+        #end if
+        ########## Integer Time ##########
+        #if $pred & $tsi_p
+            header_buff[$num_header_words] = htonl(metadata.time_spec.secs);
+            #set $num_header_words += 1
+            #set $flags |= (0x3 << 22);
+        #end if
+        ########## Fractional Time ##########
+        #if $pred & $tsf_p
+            header_buff[$num_header_words] = htonl(0);
+            #set $num_header_words += 1
+            header_buff[$num_header_words] = htonl(metadata.time_spec.ticks);
+            #set $num_header_words += 1
+            #set $flags |= (0x1 << 20);
+        #end if
+        ########## Trailer ##########
+        #if $pred & $tlr_p
+            #set $flags |= (0x1 << 26);
+            #set $num_trailer_words = 1;
+        #else
+            #set $num_trailer_words = 0;
+        #end if
+        ########## Variables ##########
+            num_header_words32 = $num_header_words;
+            num_packet_words32 = $($num_header_words + $num_trailer_words) + num_payload_words32;
+            vrt_hdr_flags = $hex($flags);
+        break;
+    #end for
+    }
+
+    //set the burst flags
+    if (metadata.start_of_burst) vrt_hdr_flags |= $hex(0x1 << 25);
+    if (metadata.end_of_burst)   vrt_hdr_flags |= $hex(0x1 << 24);
+
+    //fill in complete header word
+    header_buff[0] = htonl(vrt_hdr_flags |
+        ((packet_count & 0xf) << 16) |
+        (num_packet_words32 & 0xffff)
+    );
+}
+
+void vrt::unpack(
+    rx_metadata_t &metadata,            //output
+    const boost::uint32_t *header_buff, //input
+    size_t &num_header_words32,         //output
+    size_t &num_payload_words32,        //output
+    size_t num_packet_words32,          //input
+    size_t &packet_count                //output
+){
+    //clear the metadata
+    metadata = rx_metadata_t();
+
+    //extract vrt header
+    boost::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 or num_packet_words32 < packet_words32)
+        throw std::runtime_error("bad vrt header or packet fragment");
+    if (vrt_hdr_word & (0x7 << 29))
+        throw std::runtime_error("unsupported vrt packet type");
+
+    boost::uint8_t pred = 0;
+    if(vrt_hdr_word & $hex(0x1 << 28)) pred |= $hex($sid_p);
+    if(vrt_hdr_word & $hex(0x1 << 27)) pred |= $hex($cid_p);
+    if(vrt_hdr_word & $hex(0x3 << 22)) pred |= $hex($tsi_p);
+    if(vrt_hdr_word & $hex(0x3 << 20)) pred |= $hex($tsf_p);
+    if(vrt_hdr_word & $hex(0x1 << 26)) pred |= $hex($tlr_p);
+
+    switch(pred){
+    #for $pred in range(2**5)
+    case $pred:
+        #set $set_has_time_spec = False
+        #set $num_header_words = 1
+        ########## Stream ID ##########
+        #if $pred & $sid_p
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[$num_header_words]);
+            #set $num_header_words += 1
+        #end if
+        ########## Class ID ##########
+        #if $pred & $cid_p
+            #set $num_header_words += 1
+            #set $num_header_words += 1
+        #end if
+        ########## Integer Time ##########
+        #if $pred & $tsi_p
+            metadata.has_time_spec = true;
+            #set $set_has_time_spec = True
+            metadata.time_spec.secs = ntohl(header_buff[$num_header_words]);
+            #set $num_header_words += 1
+        #end if
+        ########## Fractional Time ##########
+        #if $pred & $tsf_p
+            #if not $set_has_time_spec
+            metadata.has_time_spec = true;
+                #set $set_has_time_spec = True
+            #end if
+            #set $num_header_words += 1
+            metadata.time_spec.ticks = ntohl(header_buff[$num_header_words]);
+            #set $num_header_words += 1
+        #end if
+        ########## Trailer ##########
+        #if $pred & $tlr_p
+            #set $num_trailer_words = 1;
+        #else
+            #set $num_trailer_words = 0;
+        #end if
+        ########## Variables ##########
+            num_header_words32 = $num_header_words;
+            num_payload_words32 = packet_words32 - $($num_header_words + $num_trailer_words);
+        break;
+    #end for
+    }
+}
+"""
+
+from Cheetah import Template
+def parse_str(_tmpl_text, **kwargs): return str(Template.Template(_tmpl_text, kwargs))
+
+if __name__ == '__main__':
+    from Cheetah import Template
+    print parse_str(TMPL_TEXT, file=__file__)
diff --git a/host/lib/transport/vrt.cpp b/host/lib/transport/vrt.cpp
index cc46b2381..bebca5db9 100644
--- a/host/lib/transport/vrt.cpp
+++ b/host/lib/transport/vrt.cpp
@@ -1,19 +1,9 @@
-//
-// 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/>.
-//
+
+
+
+/***********************************************************************
+ * This file was generated by ./gen_vrt.py on Fri Mar 26 15:33:00 2010
+ **********************************************************************/
 
 #include <uhd/transport/vrt.hpp>
 #include <boost/asio.hpp> //endianness conversion
@@ -30,26 +20,274 @@ void vrt::pack(
     size_t &num_packet_words32,    //output
     size_t packet_count            //input
 ){
-    boost::uint32_t vrt_hdr_flags = 0;
-    num_header_words32 = 1;
+    boost::uint32_t vrt_hdr_flags;
 
-    //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);
-    }
+    boost::uint8_t pred = 0;
+    if (metadata.has_stream_id) pred |= 0x1;
+    if (metadata.has_time_spec) pred |= 0xc;
 
-    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++] = 0; //unused part of fractional seconds
-        header_buff[num_header_words32++] = htonl(metadata.time_spec.ticks);
+    switch(pred){
+    case 0:
+            num_header_words32 = 1;
+            num_packet_words32 = 1 + num_payload_words32;
+            vrt_hdr_flags = 0x0;
+        break;
+    case 1:
+            header_buff[1] = htonl(metadata.stream_id);
+            num_header_words32 = 2;
+            num_packet_words32 = 2 + num_payload_words32;
+            vrt_hdr_flags = 0x10000000;
+        break;
+    case 2:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            num_header_words32 = 3;
+            num_packet_words32 = 3 + num_payload_words32;
+            vrt_hdr_flags = 0x8000000;
+        break;
+    case 3:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            num_header_words32 = 4;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0x18000000;
+        break;
+    case 4:
+            header_buff[1] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 2;
+            num_packet_words32 = 2 + num_payload_words32;
+            vrt_hdr_flags = 0xc00000;
+        break;
+    case 5:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 3;
+            num_packet_words32 = 3 + num_payload_words32;
+            vrt_hdr_flags = 0x10c00000;
+        break;
+    case 6:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 4;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0x8c00000;
+        break;
+    case 7:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 5;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0x18c00000;
+        break;
+    case 8:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 3;
+            num_packet_words32 = 3 + num_payload_words32;
+            vrt_hdr_flags = 0x100000;
+        break;
+    case 9:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 4;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0x10100000;
+        break;
+    case 10:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 5;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0x8100000;
+        break;
+    case 11:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(0);
+            header_buff[5] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 6;
+            num_packet_words32 = 6 + num_payload_words32;
+            vrt_hdr_flags = 0x18100000;
+        break;
+    case 12:
+            header_buff[1] = htonl(metadata.time_spec.secs);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 4;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0xd00000;
+        break;
+    case 13:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(metadata.time_spec.secs);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 5;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0x10d00000;
+        break;
+    case 14:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.secs);
+            header_buff[4] = htonl(0);
+            header_buff[5] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 6;
+            num_packet_words32 = 6 + num_payload_words32;
+            vrt_hdr_flags = 0x8d00000;
+        break;
+    case 15:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.secs);
+            header_buff[5] = htonl(0);
+            header_buff[6] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 7;
+            num_packet_words32 = 7 + num_payload_words32;
+            vrt_hdr_flags = 0x18d00000;
+        break;
+    case 16:
+            num_header_words32 = 1;
+            num_packet_words32 = 2 + num_payload_words32;
+            vrt_hdr_flags = 0x4000000;
+        break;
+    case 17:
+            header_buff[1] = htonl(metadata.stream_id);
+            num_header_words32 = 2;
+            num_packet_words32 = 3 + num_payload_words32;
+            vrt_hdr_flags = 0x14000000;
+        break;
+    case 18:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            num_header_words32 = 3;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0xc000000;
+        break;
+    case 19:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            num_header_words32 = 4;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0x1c000000;
+        break;
+    case 20:
+            header_buff[1] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 2;
+            num_packet_words32 = 3 + num_payload_words32;
+            vrt_hdr_flags = 0x4c00000;
+        break;
+    case 21:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 3;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0x14c00000;
+        break;
+    case 22:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 4;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0xcc00000;
+        break;
+    case 23:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.secs);
+            num_header_words32 = 5;
+            num_packet_words32 = 6 + num_payload_words32;
+            vrt_hdr_flags = 0x1cc00000;
+        break;
+    case 24:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 3;
+            num_packet_words32 = 4 + num_payload_words32;
+            vrt_hdr_flags = 0x4100000;
+        break;
+    case 25:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 4;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0x14100000;
+        break;
+    case 26:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 5;
+            num_packet_words32 = 6 + num_payload_words32;
+            vrt_hdr_flags = 0xc100000;
+        break;
+    case 27:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(0);
+            header_buff[5] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 6;
+            num_packet_words32 = 7 + num_payload_words32;
+            vrt_hdr_flags = 0x1c100000;
+        break;
+    case 28:
+            header_buff[1] = htonl(metadata.time_spec.secs);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 4;
+            num_packet_words32 = 5 + num_payload_words32;
+            vrt_hdr_flags = 0x4d00000;
+        break;
+    case 29:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(metadata.time_spec.secs);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 5;
+            num_packet_words32 = 6 + num_payload_words32;
+            vrt_hdr_flags = 0x14d00000;
+        break;
+    case 30:
+            header_buff[1] = htonl(0);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(metadata.time_spec.secs);
+            header_buff[4] = htonl(0);
+            header_buff[5] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 6;
+            num_packet_words32 = 7 + num_payload_words32;
+            vrt_hdr_flags = 0xcd00000;
+        break;
+    case 31:
+            header_buff[1] = htonl(metadata.stream_id);
+            header_buff[2] = htonl(0);
+            header_buff[3] = htonl(0);
+            header_buff[4] = htonl(metadata.time_spec.secs);
+            header_buff[5] = htonl(0);
+            header_buff[6] = htonl(metadata.time_spec.ticks);
+            num_header_words32 = 7;
+            num_packet_words32 = 8 + num_payload_words32;
+            vrt_hdr_flags = 0x1cd00000;
+        break;
     }
 
-    vrt_hdr_flags |= (metadata.start_of_burst)? (0x1 << 25) : 0;
-    vrt_hdr_flags |= (metadata.end_of_burst)?   (0x1 << 24) : 0;
-
-    num_packet_words32 = num_header_words32 + num_payload_words32;
+    //set the burst flags
+    if (metadata.start_of_burst) vrt_hdr_flags |= 0x2000000;
+    if (metadata.end_of_burst)   vrt_hdr_flags |= 0x1000000;
 
     //fill in complete header word
     header_buff[0] = htonl(vrt_hdr_flags |
@@ -80,30 +318,230 @@ void vrt::unpack(
     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++]);
-    }
+    boost::uint8_t pred = 0;
+    if(vrt_hdr_word & 0x10000000) pred |= 0x1;
+    if(vrt_hdr_word & 0x8000000) pred |= 0x2;
+    if(vrt_hdr_word & 0xc00000) pred |= 0x4;
+    if(vrt_hdr_word & 0x300000) pred |= 0x8;
+    if(vrt_hdr_word & 0x4000000) pred |= 0x10;
 
-    if (vrt_hdr_word & (0x3 << 20)){ //fractional time
-        metadata.has_time_spec = true;
-        num_header_words32++; //unused part of fractional seconds
-        metadata.time_spec.ticks = ntohl(header_buff[num_header_words32++]);
+    switch(pred){
+    case 0:
+            num_header_words32 = 1;
+            num_payload_words32 = packet_words32 - 1;
+        break;
+    case 1:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            num_header_words32 = 2;
+            num_payload_words32 = packet_words32 - 2;
+        break;
+    case 2:
+            num_header_words32 = 3;
+            num_payload_words32 = packet_words32 - 3;
+        break;
+    case 3:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 4:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[1]);
+            num_header_words32 = 2;
+            num_payload_words32 = packet_words32 - 2;
+        break;
+    case 5:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[2]);
+            num_header_words32 = 3;
+            num_payload_words32 = packet_words32 - 3;
+        break;
+    case 6:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[3]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 7:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[4]);
+            num_header_words32 = 5;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 8:
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[2]);
+            num_header_words32 = 3;
+            num_payload_words32 = packet_words32 - 3;
+        break;
+    case 9:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[3]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 10:
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[4]);
+            num_header_words32 = 5;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 11:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[5]);
+            num_header_words32 = 6;
+            num_payload_words32 = packet_words32 - 6;
+        break;
+    case 12:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[1]);
+            metadata.time_spec.ticks = ntohl(header_buff[3]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 13:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[2]);
+            metadata.time_spec.ticks = ntohl(header_buff[4]);
+            num_header_words32 = 5;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 14:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[3]);
+            metadata.time_spec.ticks = ntohl(header_buff[5]);
+            num_header_words32 = 6;
+            num_payload_words32 = packet_words32 - 6;
+        break;
+    case 15:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[4]);
+            metadata.time_spec.ticks = ntohl(header_buff[6]);
+            num_header_words32 = 7;
+            num_payload_words32 = packet_words32 - 7;
+        break;
+    case 16:
+            num_header_words32 = 1;
+            num_payload_words32 = packet_words32 - 2;
+        break;
+    case 17:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            num_header_words32 = 2;
+            num_payload_words32 = packet_words32 - 3;
+        break;
+    case 18:
+            num_header_words32 = 3;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 19:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 20:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[1]);
+            num_header_words32 = 2;
+            num_payload_words32 = packet_words32 - 3;
+        break;
+    case 21:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[2]);
+            num_header_words32 = 3;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 22:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[3]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 23:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[4]);
+            num_header_words32 = 5;
+            num_payload_words32 = packet_words32 - 6;
+        break;
+    case 24:
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[2]);
+            num_header_words32 = 3;
+            num_payload_words32 = packet_words32 - 4;
+        break;
+    case 25:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[3]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 26:
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[4]);
+            num_header_words32 = 5;
+            num_payload_words32 = packet_words32 - 6;
+        break;
+    case 27:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.ticks = ntohl(header_buff[5]);
+            num_header_words32 = 6;
+            num_payload_words32 = packet_words32 - 7;
+        break;
+    case 28:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[1]);
+            metadata.time_spec.ticks = ntohl(header_buff[3]);
+            num_header_words32 = 4;
+            num_payload_words32 = packet_words32 - 5;
+        break;
+    case 29:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[2]);
+            metadata.time_spec.ticks = ntohl(header_buff[4]);
+            num_header_words32 = 5;
+            num_payload_words32 = packet_words32 - 6;
+        break;
+    case 30:
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[3]);
+            metadata.time_spec.ticks = ntohl(header_buff[5]);
+            num_header_words32 = 6;
+            num_payload_words32 = packet_words32 - 7;
+        break;
+    case 31:
+            metadata.has_stream_id = true;
+            metadata.stream_id = ntohl(header_buff[1]);
+            metadata.has_time_spec = true;
+            metadata.time_spec.secs = ntohl(header_buff[4]);
+            metadata.time_spec.ticks = ntohl(header_buff[6]);
+            num_header_words32 = 7;
+            num_payload_words32 = packet_words32 - 8;
+        break;
     }
-
-    size_t num_trailer_words32 = (vrt_hdr_word & (0x1 << 26))? 1 : 0;
-
-    num_payload_words32 = packet_words32 - num_header_words32 - num_trailer_words32;
 }
+