1 files changed, 76 insertions, 0 deletions
diff --git a/ac3dec/bitstream.c b/ac3dec/bitstream.c
new file mode 100644
index 0000000..296d5ee
--- /dev/null
+++ b/ac3dec/bitstream.c
@@ -0,0 +1,76 @@
+/* 
+ *  bitstream.c
+ *
+ *	Copyright (C) Aaron Holtzman - Dec 1999
+ *
+ *  This file is part of ac3dec, a free AC-3 audio decoder
+ *	
+ *  ac3dec 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.
+ *   
+ *  ac3dec 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 Make; see the file COPYING.  If not, write to
+ *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
+ *
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "ac3.h"
+#include "ac3_internal.h"
+#include "bitstream.h"
+
+
+uint_8 *buffer_start = 0;
+uint_32 bits_left = 0;
+uint_32 current_word;
+
+static inline void
+bitstream_fill_current()
+{
+	current_word = *((uint_32*)buffer_start)++;
+	current_word = swab32(current_word);
+}
+
+//
+// The fast paths for _get is in the
+// bitstream.h header file so it can be inlined.
+//
+// The "bottom half" of this routine is suffixed _bh
+//
+// -ah
+//
+
+uint_32
+bitstream_get_bh(uint_32 num_bits)
+{
+	uint_32 result;
+
+	num_bits -= bits_left;
+	result = (current_word << (32 - bits_left)) >> (32 - bits_left);
+
+	bitstream_fill_current();
+
+	if(num_bits != 0)
+		result = (result << num_bits) | (current_word >> (32 - num_bits));
+	
+	bits_left = 32 - num_bits;
+
+	return result;
+}
+
+void
+bitstream_init(uint_8 *start)
+{
+	//initialize the start of the buffer
+	buffer_start = start;
+	bits_left = 0;
+}