1 files changed, 97 insertions, 0 deletions
diff --git a/gr-blocks/lib/throttle_impl.cc b/gr-blocks/lib/throttle_impl.cc
new file mode 100644
index 000000000..49743e3f2
--- /dev/null
+++ b/gr-blocks/lib/throttle_impl.cc
@@ -0,0 +1,97 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2005-2011 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio 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, or (at your option)
+ * any later version.
+ *
+ * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "throttle_impl.h"
+#include <gr_io_signature.h>
+#include <cstring>
+#include <boost/thread/thread.hpp>
+
+namespace gr {
+  namespace blocks {
+
+    throttle::sptr
+    throttle::make(size_t itemsize, double samples_per_sec)
+    {
+      return gnuradio::get_initial_sptr
+        (new throttle_impl(itemsize, samples_per_sec));
+    }
+
+    throttle_impl::throttle_impl(size_t itemsize,
+                                 double samples_per_second)
+      : gr_sync_block("throttle",
+                      gr_make_io_signature(1, 1, itemsize),
+                      gr_make_io_signature(1, 1, itemsize)),
+        d_itemsize(itemsize)
+    {
+      set_sample_rate(samples_per_second);
+    }
+
+    throttle_impl::~throttle_impl()
+    {
+    }
+
+    void
+    throttle_impl::set_sample_rate(double rate)
+    {
+      //changing the sample rate performs a reset of state params
+      d_start = boost::get_system_time();
+      d_total_samples = 0;
+      d_samps_per_tick = rate/boost::posix_time::time_duration::ticks_per_second();
+      d_samps_per_us = rate/1e6;
+    }
+
+    double
+    throttle_impl::sample_rate() const
+    {
+      return d_samps_per_us * 1e6;
+    }
+
+    int
+    throttle_impl::work(int noutput_items,
+                        gr_vector_const_void_star &input_items,
+                        gr_vector_void_star &output_items)
+    {
+      //calculate the expected number of samples to have passed through
+      boost::system_time now = boost::get_system_time();
+      boost::int64_t ticks = (now - d_start).ticks();
+      uint64_t expected_samps = uint64_t(d_samps_per_tick*ticks);
+
+      //if the expected samples was less, we need to throttle back
+      if(d_total_samples > expected_samps) {
+        boost::this_thread::sleep(boost::posix_time::microseconds
+                                  (long((d_total_samples - expected_samps)/d_samps_per_us)));
+      }
+
+      //copy all samples output[i] <= input[i]
+      const char *in = (const char *)input_items[0];
+      char *out = (char *)output_items[0];
+      std::memcpy(out, in, noutput_items * d_itemsize);
+      d_total_samples += noutput_items;
+      return noutput_items;
+    }
+
+  } /* namespace blocks */
+} /* namespace gr */