--- trunk/xvidcore/src/bitstream/bitstream.h	2005/05/23 09:29:43	1617
+++ branches/release-1_3-branch/xvidcore/src/bitstream/bitstream.h	2019/11/12 14:48:35	2180
@@ -19,7 +19,7 @@
  *  along with this program ; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  *
- * $Id: bitstream.h,v 1.22 2005-05-23 09:29:43 Skal Exp $
+ * $Id$
  *
  ****************************************************************************/
 
@@ -137,7 +137,8 @@
 
 void BitstreamWriteVolHeader(Bitstream * const bs,
 							 const MBParam * pParam,
-							 const FRAMEINFO * const frame);
+							 const FRAMEINFO * const frame,
+							 const int num_slices);
 
 void BitstreamWriteVopHeader(Bitstream * const bs,
 							 const MBParam * pParam,
@@ -162,6 +163,18 @@
                                const FRAMEINFO * const frame,
                                int mbnum);
 
+/*****************************************************************************
+ * Bitstream
+ ****************************************************************************/
+
+/* Input buffer should be readable as full chunks of 8bytes, including
+the end of the buffer. Padding might be appropriate. If only chunks
+of 4bytes are applicable, define XVID_SAFE_BS_TAIL. Note that this will
+slow decoding, so consider this as a last-resort solution */
+#ifndef XVID_HAVE_PADDED_BS_BUFFER
+#define XVID_SAFE_BS_TAIL
+#endif
+
 /* initialise bitstream structure */
 
 static void __inline
@@ -193,8 +206,12 @@
 #endif
 	bs->bufb = tmp;
 
-	bs->buf = 0;
-	bs->pos = bs->initpos = bitpos*8;
+	bs->pos = bs->initpos = (uint32_t) bitpos*8;
+	/* preserve the intervening bytes */
+	if (bs->initpos > 0)
+		bs->buf = bs->bufa & (0xffffffff << (32 - bs->initpos));
+	else
+		bs->buf = 0;
 	bs->length = length;
 }
 
@@ -220,7 +237,11 @@
 #endif
 	bs->bufb = tmp;
 
-	bs->buf = 0;
+	/* preserve the intervening bytes */
+	if (bs->initpos > 0)
+		bs->buf = bs->bufa & (0xffffffff << (32 - bs->initpos));
+	else
+		bs->buf = 0;
 	bs->pos = bs->initpos;
 }
 
@@ -255,12 +276,22 @@
 		uint32_t tmp;
 
 		bs->bufa = bs->bufb;
-		tmp = *((uint32_t *) bs->tail + 2);
+#if defined(XVID_SAFE_BS_TAIL)
+		if (bs->tail<(bs->start+((bs->length+3)>>2)))
+#endif
+		{
+			tmp = *((uint32_t *) bs->tail + 2);
 #ifndef ARCH_IS_BIG_ENDIAN
-		BSWAP(tmp);
+			BSWAP(tmp);
+#endif
+			bs->bufb = tmp;
+			bs->tail++;
+		}
+#if defined(XVID_SAFE_BS_TAIL)
+		else {
+			bs->bufb = 0;
+		}
 #endif
-		bs->bufb = tmp;
-		bs->tail++;
 		bs->pos -= 32;
 	}
 }