Merge branch 'dfsg-orig'

[debian/gnuradio] / gr-noaa / lib / noaa_hrpt_deframer.cc

diff --git a/gr-noaa/lib/noaa_hrpt_deframer.cc b/gr-noaa/lib/noaa_hrpt_deframer.cc
new file mode 100644 (file)
index 0000000..1a2af6c
--- /dev/null
+++ b/gr-noaa/lib/noaa_hrpt_deframer.cc
@@ -0,0 +1,126 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2009 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 <noaa_hrpt_deframer.h>
+#include <gr_io_signature.h>
+#include <noaa_hrpt.h>
+#include <cstring>
+#include <cstdio>
+
+#define ST_IDLE   0
+#define ST_SYNCED 1
+
+noaa_hrpt_deframer_sptr
+noaa_make_hrpt_deframer()
+{
+  return gnuradio::get_initial_sptr(new noaa_hrpt_deframer());
+}
+
+noaa_hrpt_deframer::noaa_hrpt_deframer()
+  : gr_block("noaa_hrpt_deframer",
+            gr_make_io_signature(1, 1, sizeof(char)),
+            gr_make_io_signature(1, 1, sizeof(short)))
+{
+  set_output_multiple(6); // room for writing full sync when received
+  d_mid_bit = true;
+  d_last_bit = 0;
+  enter_idle();
+}
+
+void
+noaa_hrpt_deframer::enter_idle()
+{
+  d_state = ST_IDLE;
+}
+
+void
+noaa_hrpt_deframer::enter_synced()
+{
+  d_state = ST_SYNCED;
+  d_bit_count = HRPT_BITS_PER_WORD;
+  d_word_count = HRPT_MINOR_FRAME_WORDS-HRPT_SYNC_WORDS;
+  d_word = 0;
+}
+
+int
+noaa_hrpt_deframer::general_work(int noutput_items,
+                                gr_vector_int &ninput_items,
+                                gr_vector_const_void_star &input_items,
+                                gr_vector_void_star &output_items)
+{
+  int ninputs = ninput_items[0];
+  const char *in = (const char *)input_items[0];
+  unsigned short *out = (unsigned short *)output_items[0];
+
+  int i = 0, j = 0;
+  while (i < ninputs && j < noutput_items) {
+    char bit = in[i++];
+    char diff = bit^d_last_bit;
+    d_last_bit = bit;
+
+    // Wait for transition if not synced, otherwise, alternate bits
+    if (d_mid_bit && (diff | (d_state == ST_SYNCED))) {
+      switch (d_state) {
+      case ST_IDLE:
+       d_shifter = (d_shifter << 1) | bit; // MSB transmitted first
+       
+       if ((d_shifter & 0x0FFFFFFFFFFFFFFFLL) == HRPT_MINOR_FRAME_SYNC) {
+         out[j++] = HRPT_SYNC1;
+         out[j++] = HRPT_SYNC2;
+         out[j++] = HRPT_SYNC3;
+         out[j++] = HRPT_SYNC4;
+         out[j++] = HRPT_SYNC5;
+         out[j++] = HRPT_SYNC6;
+         enter_synced();
+       }
+       break;
+       
+      case ST_SYNCED:
+       d_word = (d_word << 1) | bit; // MSB transmitted first
+       if (--d_bit_count == 0) {
+         out[j++] = d_word;
+         d_word = 0;
+         d_bit_count = HRPT_BITS_PER_WORD;
+         if (--d_word_count == 0) {
+           enter_idle();
+         }
+       }
+       break;
+       
+      default:
+       throw std::runtime_error("noaa_hrpt_deframer: bad state\n");
+      }
+
+      d_mid_bit = false;
+    }
+    else {
+      d_mid_bit = true;
+    }
+  }
+
+  consume_each(i);
+  return j;
+}