Added ac3dec 0.6.1 with native ALSA driver.

ac3dec/libac3/bitstream.c

@@ -0,0 +1,129 @@
+/* 
+ *  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"
+
+#define BUFFER_SIZE 4096
+
+static uint_8 buffer[BUFFER_SIZE];
+
+static uint_8 *buffer_start, *buffer_end;
+static uint_8 *chunk_start, *chunk_end;
+
+uint_32 bits_left;
+uint_32 current_word;
+
+void (*bitstream_fill_buffer)(uint_8**,uint_8**);
+
+uint_8 bitstream_get_byte(void)
+{
+	if(chunk_start == chunk_end)
+		bitstream_fill_buffer(&chunk_start,&chunk_end);
+
+	return (*chunk_start++);
+}
+
+uint_8 *bitstream_get_buffer_start(void)
+{
+	return buffer_start;
+}
+
+void
+bitstream_buffer_frame(uint_32 frame_size)
+{
+  uint_32 bytes_read;
+  uint_32 num_bytes;
+
+  bytes_read = 0;
+
+  do
+  {
+    if(chunk_start > chunk_end)
+			printf("argh!\n");
+    if(chunk_start == chunk_end)
+      bitstream_fill_buffer(&chunk_start,&chunk_end);
+
+    num_bytes = chunk_end - chunk_start;
+
+    if(bytes_read + num_bytes > frame_size)
+      num_bytes = frame_size - bytes_read;
+
+    memcpy(&buffer[bytes_read], chunk_start, num_bytes);
+
+    bytes_read += num_bytes;
+    chunk_start += num_bytes;
+  }
+  while (bytes_read != frame_size);
+
+  buffer_start = buffer;
+  buffer_end   = buffer + frame_size;
+
+	bits_left = 0;
+}
+
+
+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(void(*fill_function)(uint_8**,uint_8**))
+{
+	// Setup the buffer fill callback 
+	bitstream_fill_buffer = fill_function;
+}