1 files changed, 109 insertions, 0 deletions
diff --git a/gnuradio-core/src/lib/general/gr_throttle.cc b/gnuradio-core/src/lib/general/gr_throttle.cc
new file mode 100644
index 000000000..9fbf23edd
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gr_throttle.cc
@@ -0,0 +1,109 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2005 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 2, 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gr_throttle.h>
+#include <gr_io_signature.h>
+#include <errno.h>
+#include <stdio.h>
+#include <math.h>
+#ifdef HAVE_TIME_H
+#include <time.h>
+#endif
+
+
+#ifdef HAVE_NANOSLEEP
+void
+gr_nanosleep(struct timespec *ts)
+{
+  struct timespec	*req = ts;
+  struct timespec	rem;
+  int r = nanosleep(req, &rem);
+  while (r < 0 && errno == EINTR){
+    req = &rem;
+    r = nanosleep(req, &rem);
+  }
+  if (r < 0)
+    perror ("gr_nanosleep");
+}
+#endif
+
+gr_throttle_sptr
+gr_make_throttle(size_t itemsize, double samples_per_sec)
+{
+  return gr_throttle_sptr(new gr_throttle(itemsize, samples_per_sec));
+}
+
+gr_throttle::gr_throttle(size_t itemsize, double samples_per_sec)
+  : gr_sync_block("throttle",
+		  gr_make_io_signature(1, 1, itemsize),
+		  gr_make_io_signature(1, 1, itemsize)),
+    d_itemsize(itemsize), d_samples_per_sec(samples_per_sec),
+    d_total_samples(0)
+{
+#ifdef HAVE_GETTIMEOFDAY
+  gettimeofday(&d_start, 0);
+#endif  
+}
+
+gr_throttle::~gr_throttle()
+{
+}
+
+int
+gr_throttle::work (int noutput_items,
+		   gr_vector_const_void_star &input_items,
+		   gr_vector_void_star &output_items)
+{
+  const char *in = (const char *) input_items[0];
+  char *out = (char *) output_items[0];
+
+#if defined(HAVE_GETTIMEOFDAY) && defined(HAVE_NANOSLEEP)
+  //
+  // If our average sample rate exceeds our target sample rate,
+  // delay long enough to reduce to our target rate.
+  //
+  struct timeval now;
+  gettimeofday(&now, 0);
+  long t_usec = now.tv_usec - d_start.tv_usec;
+  long t_sec  = now.tv_sec - d_start.tv_sec;
+  double t = (double)t_sec + (double)t_usec * 1e-6;
+  if (t < 1e-6)		// avoid unlikely divide by zero
+    t = 1e-6;
+
+  double actual_samples_per_sec = d_total_samples / t;
+  if (actual_samples_per_sec > d_samples_per_sec){	// need to delay
+    double delay = d_total_samples / d_samples_per_sec - t;
+    struct timespec ts;
+    ts.tv_sec = (time_t)floor(delay);
+    ts.tv_nsec = (long)((delay - floor(delay)) * 1e9);
+    gr_nanosleep(&ts);
+  }
+#endif  
+
+  memcpy(out, in, noutput_items * d_itemsize);
+  d_total_samples += noutput_items;
+  return noutput_items;
+}