1 files changed, 87 insertions, 0 deletions
diff --git a/gr-blocks/lib/keep_m_in_n_impl.cc b/gr-blocks/lib/keep_m_in_n_impl.cc
new file mode 100644
index 000000000..312b09c25
--- /dev/null
+++ b/gr-blocks/lib/keep_m_in_n_impl.cc
@@ -0,0 +1,87 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2012 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 "keep_m_in_n_impl.h"
+#include <gr_io_signature.h>
+
+namespace gr {
+  namespace blocks {
+
+    keep_m_in_n::sptr keep_m_in_n::make(size_t itemsize, int m, int n, int offset)
+    {
+      return gnuradio::get_initial_sptr(new keep_m_in_n_impl(itemsize, m, n, offset));
+    }
+
+    keep_m_in_n_impl::keep_m_in_n_impl(size_t itemsize, int m, int n, int offset)
+      : gr_block("keep_m_in_n",
+		 gr_make_io_signature (1, 1, itemsize),
+		 gr_make_io_signature (1, 1, itemsize)),
+	d_m(m),
+	d_n(n),
+	d_offset(offset),
+	d_itemsize(itemsize)
+    {
+      // sanity checking
+      assert(d_m > 0);
+      assert(d_n > 0);
+      assert(d_m <= d_n);
+      assert(d_offset <= (d_n-d_m));
+      
+      set_output_multiple(m);
+    }
+
+    void
+    keep_m_in_n_impl::forecast(int noutput_items, gr_vector_int &ninput_items_required)
+    {
+      ninput_items_required[0] = d_n*(noutput_items/d_m);
+    }
+
+    int
+    keep_m_in_n_impl::general_work(int noutput_items,
+				   gr_vector_int &ninput_items,
+				   gr_vector_const_void_star &input_items,
+				   gr_vector_void_star &output_items)
+    {
+      uint8_t* out = (uint8_t*)output_items[0];
+      const uint8_t* in = (const uint8_t*)input_items[0];
+      
+      // iterate over data blocks of size {n, input : m, output}
+      int blks = std::min(noutput_items/d_m, ninput_items[0]/d_n);
+
+      for(int i=0; i<blks; i++) {
+	// set up copy pointers
+	const uint8_t* iptr = &in[(i*d_n + d_offset)*d_itemsize];
+	uint8_t* optr = &out[i*d_m*d_itemsize];
+	// perform copy
+	memcpy( optr, iptr, d_m*d_itemsize );
+      }
+      
+      consume_each(d_n);
+      return d_m;
+    }
+    
+  } /* namespace blocks */
+} /* namespace gr */