restored bitMask for shift values

since corrupted bitstreams can generate too large values.

This slightly reduces the benefits from clang on my laptop.
gcc results and code generation are not affected.

diff --git a/lib/common/bitstream.h b/lib/common/bitstream.h
index f8ec7efc9a96b5876169c6210e3873ed81aee3f0..ef89b9878e2208ef11083e31632875a923dca1de 100644 (file)
--- a/lib/common/bitstream.h
+++ b/lib/common/bitstream.h
@@ -339,9 +339,10 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start)
 
 MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits)
 {
+    U32 const regMask = sizeof(bitContainer)*8 - 1;
+    /* if start > regMask, bitstream is corrupted, and result is undefined */
     assert(nbBits < BIT_MASK_SIZE);
-    /* if start > bitMask, bitstream is corrupted, and result is undefined */
-    return (bitContainer >> start) & BIT_mask[nbBits];
+    return (bitContainer >> (start & regMask)) & BIT_mask[nbBits];
 }
 
 MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)