AK: Prevent bit counter underflows in the new BitStream

Our current `peek_bits` function allows retrieving more bits than we can
actually provide, so whenever someone discards the requested bit count
afterwards we were underflowing the value instead.

1 files changed, 4 insertions, 0 deletions

diff --git a/AK/BitStream.h b/AK/BitStream.h
index 3ddca57267..c03ac22ada 100644
--- a/AK/BitStream.h
+++ b/AK/BitStream.h
@@ -222,6 +222,10 @@ public:
 
     ALWAYS_INLINE void discard_previously_peeked_bits(u8 count)
     {
+        // We allow "retrieving" more bits than we can provide, but we need to make sure that we don't underflow the current bit counter.
+        if (count > m_bit_count)
+            count = m_bit_count;
+
         m_bit_offset += count;
         m_bit_count -= count;
     }