* add support for liba52

Originally committed as revision 411 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 103 insertions, 0 deletions

diff --git a/libavcodec/liba52/bitstream.c b/libavcodec/liba52/bitstream.c
new file mode 100644
index 0000000000..70621c7c11
--- /dev/null
+++ b/libavcodec/liba52/bitstream.c
@@ -0,0 +1,103 @@
+/*
+ * bitstream.c
+ * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
+ * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
+ *
+ * This file is part of a52dec, a free ATSC A-52 stream decoder.
+ * See http://liba52.sourceforge.net/ for updates.
+ *
+ * a52dec 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.
+ *
+ * a52dec 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "config.h"
+
+#include <inttypes.h>
+
+#include "a52.h"
+#include "a52_internal.h"
+#include "bitstream.h"
+
+#define BUFFER_SIZE 4096
+
+static uint32_t * buffer_start;
+
+uint32_t a52_bits_left;
+uint32_t a52_current_word;
+
+void a52_bitstream_set_ptr (uint8_t * buf)
+{
+    int align;
+
+    align = (long)buf & 3;
+    buffer_start = (uint32_t *) (buf - align);
+    a52_bits_left = 0;
+    bitstream_get (align * 8);
+}
+
+static inline void
+bitstream_fill_current()
+{
+    uint32_t tmp;
+
+    tmp = *(buffer_start++);
+    a52_current_word = swab32 (tmp);
+}
+
+/*
+ * 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
+ */
+
+uint32_t
+a52_bitstream_get_bh(uint32_t num_bits)
+{
+    uint32_t result;
+
+    num_bits -= a52_bits_left;
+    result = ((a52_current_word << (32 - a52_bits_left)) >>
+	      (32 - a52_bits_left));
+
+    bitstream_fill_current();
+
+    if(num_bits != 0)
+	result = (result << num_bits) | (a52_current_word >> (32 - num_bits));
+
+    a52_bits_left = 32 - num_bits;
+
+    return result;
+}
+
+int32_t
+a52_bitstream_get_bh_2(uint32_t num_bits)
+{
+    int32_t result;
+
+    num_bits -= a52_bits_left;
+    result = ((((int32_t)a52_current_word) << (32 - a52_bits_left)) >>
+	      (32 - a52_bits_left));
+
+    bitstream_fill_current();
+
+    if(num_bits != 0)
+	result = (result << num_bits) | (a52_current_word >> (32 - num_bits));
+	
+    a52_bits_left = 32 - num_bits;
+
+    return result;
+}