Module: libav Branch: master Commit: f59bb3d8f3eb50aa182b0d7ae209848b94a507cc
Author: Mans Rullgard <[email protected]> Committer: Mans Rullgard <[email protected]> Date: Sun Oct 9 12:57:08 2011 +0100 mathops: remove undefined behaviour from sign_extend() This function intentionally overflows the signed range on the left shift. Using this type-punning avoids errors from the overflow checker without disabling this test globally. Signed-off-by: Mans Rullgard <[email protected]> --- libavcodec/mathops.h | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/libavcodec/mathops.h b/libavcodec/mathops.h index ec76eaa..45b1ecf 100644 --- a/libavcodec/mathops.h +++ b/libavcodec/mathops.h @@ -116,7 +116,9 @@ static inline av_const int mid_pred(int a, int b, int c) #ifndef sign_extend static inline av_const int sign_extend(int val, unsigned bits) { - return (val << ((8 * sizeof(int)) - bits)) >> ((8 * sizeof(int)) - bits); + unsigned shift = 8 * sizeof(int) - bits; + union { unsigned u; int s; } v = { (unsigned) val << shift }; + return v.s >> shift; } #endif _______________________________________________ libav-commits mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-commits
