Initial revision

CVS patchset: 1
CVS date: 2001/04/18 22:33:39

1 files changed, 79 insertions, 0 deletions

diff --git a/src/libac3/bitstream.c b/src/libac3/bitstream.c
new file mode 100644
index 000000000..78ac0eca7
--- /dev/null
+++ b/src/libac3/bitstream.c
@@ -0,0 +1,79 @@
+/* 
+ *  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 <inttypes.h>
+
+#include <bswap.h>
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "ac3.h"
+#include "ac3_internal.h"
+#include "bitstream.h"
+
+
+uint32_t ac3bits_left = 0;
+uint64_t ac3current_word;
+uint64_t *buffer_start = 0;
+
+
+static inline uint64_t getdword (void)
+{
+	return be2me_64 (*buffer_start++);
+}
+
+
+static inline void bitstream_fill_current (void)
+{
+	//ac3current_word = bswap_64 (*buffer_start++);
+	ac3current_word = getdword ();
+}
+
+
+uint32_t bitstream_get_bh (uint32_t num_bits)
+{
+	uint32_t result;
+
+	num_bits -= ac3bits_left;
+	result = (ac3current_word << (64 - ac3bits_left)) >> (64 - ac3bits_left);
+
+	bitstream_fill_current();
+
+	if(num_bits != 0)
+		result = (result << num_bits) | (ac3current_word >> (64 - num_bits));
+	
+	ac3bits_left = 64 - num_bits;
+
+	return result;
+}
+
+
+void bitstream_init (uint8_t *start)
+{
+	//initialize the start of the buffer
+	buffer_start = (uint64_t *) start;
+	ac3bits_left = 0;
+}