1 files changed, 167 insertions, 0 deletions
diff --git a/src/gallium/auxiliary/vl/vl_bitstream_parser.c b/src/gallium/auxiliary/vl/vl_bitstream_parser.c
new file mode 100644
index 0000000000..3193ea5f41
--- /dev/null
+++ b/src/gallium/auxiliary/vl/vl_bitstream_parser.c
@@ -0,0 +1,167 @@
+/**************************************************************************
+ * 
+ * Copyright 2009 Younes Manton.
+ * All Rights Reserved.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ * 
+ **************************************************************************/
+
+#include "vl_bitstream_parser.h"
+#include <assert.h>
+#include <limits.h>
+#include <util/u_memory.h>
+
+static unsigned
+grab_bits(unsigned cursor, unsigned how_many_bits, unsigned bitstream_elt)
+{
+   unsigned excess_bits = sizeof(unsigned) * CHAR_BIT - how_many_bits - cursor;
+	
+   assert(cursor < sizeof(unsigned) * CHAR_BIT);
+   assert(how_many_bits > 0 && how_many_bits <= sizeof(unsigned) * CHAR_BIT);
+   assert(cursor + how_many_bits <= sizeof(unsigned) * CHAR_BIT);
+
+   return (bitstream_elt << excess_bits) >> (excess_bits + cursor);
+}
+
+static unsigned
+show_bits(unsigned cursor, unsigned how_many_bits, const unsigned *bitstream)
+{	
+   unsigned cur_int = cursor / (sizeof(unsigned) * CHAR_BIT);
+   unsigned cur_bit = cursor % (sizeof(unsigned) * CHAR_BIT);
+	
+   assert(bitstream);
+	
+   if (cur_bit + how_many_bits > sizeof(unsigned) * CHAR_BIT) {
+      unsigned lower = grab_bits(cur_bit, sizeof(unsigned) * CHAR_BIT - cur_bit,
+                                 bitstream[cur_int]);
+      unsigned upper = grab_bits(0, cur_bit + how_many_bits - sizeof(unsigned) * CHAR_BIT,
+                                 bitstream[cur_int + 1]);
+      return lower | upper << (sizeof(unsigned) * CHAR_BIT - cur_bit);
+   }
+   else
+      return grab_bits(cur_bit, how_many_bits, bitstream[cur_int]);
+}
+
+bool vl_bitstream_parser_init(struct vl_bitstream_parser *parser,
+                              unsigned num_bitstreams,
+                              const void **bitstreams,
+                              const unsigned *sizes)
+{
+   assert(parser);
+   assert(num_bitstreams);
+   assert(bitstreams);
+   assert(sizes);
+
+   parser->num_bitstreams = num_bitstreams;
+   parser->bitstreams = (const unsigned**)bitstreams;
+   parser->sizes = sizes;
+   parser->cur_bitstream = 0;
+   parser->cursor = 0;
+
+   return true;
+}
+
+void vl_bitstream_parser_cleanup(struct vl_bitstream_parser *parser)
+{
+   assert(parser);
+}
+
+unsigned
+vl_bitstream_parser_get_bits(struct vl_bitstream_parser *parser,
+                             unsigned how_many_bits)
+{
+   unsigned bits;
+
+   assert(parser);
+
+   bits = vl_bitstream_parser_show_bits(parser, how_many_bits);
+
+   vl_bitstream_parser_forward(parser, how_many_bits);
+
+   return bits;
+}
+
+unsigned
+vl_bitstream_parser_show_bits(struct vl_bitstream_parser *parser,
+                              unsigned how_many_bits)
+{	
+   unsigned bits = 0;
+   unsigned shift = 0;
+   unsigned cursor;
+   unsigned cur_bitstream;
+
+   assert(parser);
+
+   cursor = parser->cursor;
+   cur_bitstream = parser->cur_bitstream;
+
+   while (1) {
+      unsigned bits_left = parser->sizes[cur_bitstream] * CHAR_BIT - cursor;
+      unsigned bits_to_show = how_many_bits > bits_left ? bits_left : how_many_bits;
+
+      bits |= show_bits(cursor, bits_to_show,
+                        parser->bitstreams[cur_bitstream]) << shift;
+		
+      if (how_many_bits > bits_to_show) {
+         how_many_bits -= bits_to_show;
+         cursor = 0;
+         ++cur_bitstream;
+         shift += bits_to_show;
+      }
+      else
+         break;
+   }
+
+   return bits;
+}
+
+void vl_bitstream_parser_forward(struct vl_bitstream_parser *parser,
+                                 unsigned how_many_bits)
+{
+   assert(parser);
+   assert(how_many_bits);
+
+   parser->cursor += how_many_bits;
+
+   while (parser->cursor > parser->sizes[parser->cur_bitstream] * CHAR_BIT) {
+      parser->cursor -= parser->sizes[parser->cur_bitstream++] * CHAR_BIT;
+      assert(parser->cur_bitstream < parser->num_bitstreams);
+   }
+}
+
+void vl_bitstream_parser_rewind(struct vl_bitstream_parser *parser,
+                                unsigned how_many_bits)
+{
+   signed c;
+	
+   assert(parser);
+   assert(how_many_bits);
+	
+   c = parser->cursor - how_many_bits;
+
+   while (c < 0) {
+      c += parser->sizes[parser->cur_bitstream--] * CHAR_BIT;
+      assert(parser->cur_bitstream < parser->num_bitstreams);
+   }
+
+   parser->cursor = (unsigned)c;
+}