From e20160b7cc480176ba629ebfbe9fb073963c25d3 Mon Sep 17 00:00:00 2001
From: Johnathan Corgan <jcorgan@corganenterprises.com>
Date: Sat, 19 Jun 2010 11:27:56 -0700
Subject: [PATCH] gr-usrp2: implement start_streaming_at(usrp2::fpga_timestamp
 time)

This new method on usrp2.sink_* causes the first TX sample data to be
sent at the FPGA clock time specified, with all further data immediately
following.

u = usrp2.sink_32fc() # or 16sc
...configure sink here...
u.sync_to_pps()
...delay a second for PPS to have happened
u.start_streaming_at(int(100e6)) # start TX stream one second later
...start flowgraph here...

If this function is not called, all transmit data will be sent
immediately (the prior behavior).
---
 gr-usrp2/src/usrp2.i            |  2 ++
 gr-usrp2/src/usrp2_sink_16sc.cc | 16 ++++++++++++----
 gr-usrp2/src/usrp2_sink_32fc.cc | 16 ++++++++++++----
 gr-usrp2/src/usrp2_sink_base.cc | 11 ++++++++++-
 gr-usrp2/src/usrp2_sink_base.h  |  8 ++++++++
 5 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/gr-usrp2/src/usrp2.i b/gr-usrp2/src/usrp2.i
index d1fa091f..2a79fad4 100644
--- a/gr-usrp2/src/usrp2.i
+++ b/gr-usrp2/src/usrp2.i
@@ -32,6 +32,7 @@
 
 %include <usrp2/tune_result.h>
 %include <usrp2/mimo_config.h>
+%include <usrp2/metadata.h>
 
 %template(uint32_t_vector) std::vector<uint32_t>;
 
@@ -163,6 +164,7 @@ public:
   bool write_gpio(uint16_t value, uint16_t mask);
   %rename(_real_read_gpio) read_gpio;
   bool read_gpio(uint16_t *value);
+  bool start_streaming_at(usrp2::fpga_timestamp time);
 };
 
 // ----------------------------------------------------------------
diff --git a/gr-usrp2/src/usrp2_sink_16sc.cc b/gr-usrp2/src/usrp2_sink_16sc.cc
index 1e7c54dc..75cc1f4a 100644
--- a/gr-usrp2/src/usrp2_sink_16sc.cc
+++ b/gr-usrp2/src/usrp2_sink_16sc.cc
@@ -67,12 +67,20 @@ usrp2_sink_16sc::work(int noutput_items,
     return 0;
 
   usrp2::tx_metadata metadata;
-  metadata.timestamp = -1;
-  metadata.send_now = 1;
+
+  // Set TX metadata to either start time or now
+  if (d_should_wait == true) {
+    metadata.timestamp = d_tx_time;
+    metadata.send_now = 0;
+    d_should_wait = false;
+  }
+  else {
+    metadata.timestamp = -1;
+    metadata.send_now = 1;
+  }
   metadata.start_of_burst = 1;
 
-  bool ok = d_u2->tx_16sc(0,  // FIXME: someday, streams will have channel numbers
-			  in, noutput_items, &metadata);
+  bool ok = d_u2->tx_16sc(0, in, noutput_items, &metadata);
   if (!ok){
     std::cerr << "usrp2_sink_16sc: tx_16sc failed" << std::endl;
     return -1;	// say we're done
diff --git a/gr-usrp2/src/usrp2_sink_32fc.cc b/gr-usrp2/src/usrp2_sink_32fc.cc
index b1e28a82..fa75b380 100644
--- a/gr-usrp2/src/usrp2_sink_32fc.cc
+++ b/gr-usrp2/src/usrp2_sink_32fc.cc
@@ -67,12 +67,20 @@ usrp2_sink_32fc::work(int noutput_items,
     return 0;
 
   usrp2::tx_metadata metadata;
-  metadata.timestamp = -1;
-  metadata.send_now = 1;
+
+  // Set TX metadata to either start time or now
+  if (d_should_wait == true) {
+    metadata.timestamp = d_tx_time;
+    metadata.send_now = 0;
+    d_should_wait = false;
+  }
+  else {
+    metadata.timestamp = -1;
+    metadata.send_now = 1;
+  }
   metadata.start_of_burst = 1;
 
-  bool ok = d_u2->tx_32fc(0, // FIXME: someday, streams will have channel numbers
-			  in, noutput_items, &metadata);
+  bool ok = d_u2->tx_32fc(0, in, noutput_items, &metadata);
   if (!ok){
     std::cerr << "usrp2_sink_32fc: tx_32fc failed" << std::endl;
     return -1;	// say we're done
diff --git a/gr-usrp2/src/usrp2_sink_base.cc b/gr-usrp2/src/usrp2_sink_base.cc
index ce473f23..c9b34a54 100644
--- a/gr-usrp2/src/usrp2_sink_base.cc
+++ b/gr-usrp2/src/usrp2_sink_base.cc
@@ -36,7 +36,9 @@ usrp2_sink_base::usrp2_sink_base(const char *name,
   : usrp2_base(name,
                input_signature,
 	       gr_make_io_signature(0, 0, 0),
-	       ifc, mac)
+	       ifc, mac),
+    d_should_wait(false),
+    d_tx_time(0)
 {
   // NOP
 }
@@ -155,3 +157,10 @@ bool usrp2_sink_base::read_gpio(uint16_t *value)
 {
   return d_u2->read_gpio(usrp2::GPIO_TX_BANK, value);
 }
+
+bool usrp2_sink_base::start_streaming_at(usrp2::fpga_timestamp time)
+{
+  d_should_wait = true;
+  d_tx_time = time;
+  return true;
+}
diff --git a/gr-usrp2/src/usrp2_sink_base.h b/gr-usrp2/src/usrp2_sink_base.h
index 38dc4f23..d831d4df 100644
--- a/gr-usrp2/src/usrp2_sink_base.h
+++ b/gr-usrp2/src/usrp2_sink_base.h
@@ -37,6 +37,9 @@ protected:
 		  const std::string &mac)
     throw (std::runtime_error);
 
+  bool d_should_wait;
+  usrp2::fpga_timestamp d_tx_time;
+
 public:
   ~usrp2_sink_base();
 
@@ -139,6 +142,11 @@ public:
    * \brief Read daughterboard GPIO pin values
    */
   bool read_gpio(uint16_t *value);
+
+  /*!
+   * \brief First samples begin streaming to USRP2 at given time
+   */
+  bool start_streaming_at(usrp2::fpga_timestamp time);
 };
 
 #endif /* INCLUDED_USRP2_SINK_BASE_H */
-- 
2.30.2