Allow creation of ATMOS sync on channel 14.

[libdcp.git] / src / bitstream.cc

diff --git a/src/bitstream.cc b/src/bitstream.cc
new file mode 100644 (file)
index 0000000..13d5ae4
--- /dev/null
+++ b/src/bitstream.cc
@@ -0,0 +1,89 @@
+/*
+    Copyright (C) 2020 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp 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 of the License, or
+    (at your option) any later version.
+
+    libdcp 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 libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+
+#include "bitstream.h"
+#include "dcp_assert.h"
+#include <iostream>
+#include <stdint.h>
+#include <string.h>
+
+
+using namespace dcp;
+
+
+void
+Bitstream::write_bit (bool bit)
+{
+       if (_crc) {
+               _crc->process_bit (bit);
+       }
+       _data.push_back (bit);
+}
+
+
+void
+Bitstream::write_from_byte (uint8_t byte, int bits)
+{
+       for (int i = bits - 1; i >= 0; --i) {
+               write_bit ((byte >> i) & 1);
+       }
+}
+
+
+void
+Bitstream::write_from_word (uint32_t word, int bits)
+{
+       for (int i = bits - 1; i >= 0; --i) {
+               write_bit ((word >> i) & 1);
+       }
+}
+
+
+void
+Bitstream::start_crc (uint16_t poly)
+{
+       DCP_ASSERT (!static_cast<bool>(_crc));
+       _crc = boost::crc_basic<16> (poly);
+}
+
+
+void
+Bitstream::write_crc ()
+{
+       DCP_ASSERT (static_cast<bool>(_crc));
+       uint16_t crc = _crc->checksum();
+       write_from_word (crc, 16);
+       _crc = boost::none;
+}
+