[FFmpeg-devel] [PATCH 3/3] Deobfuscate LE SHOW_[SU]BITS; these are simple sign/zero extend

Mans Rullgard mans
Sun Feb 21 01:35:59 CET 2010


---
 libavcodec/get_bits.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index bb40ff4..7c4ee43 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -166,10 +166,10 @@ for examples see get_bits, show_bits, skip_bits, get_vlc
 
 # ifdef ALT_BITSTREAM_READER_LE
 #   define SHOW_UBITS(name, gb, num)\
-        ((name##_cache) & (NEG_USR32(0xffffffff,num)))
+        zero_extend(name##_cache, num)
 
 #   define SHOW_SBITS(name, gb, num)\
-        NEG_SSR32((name##_cache)<<(32-(num)), num)
+        sign_extend(name##_cache, num)
 # else
 #   define SHOW_UBITS(name, gb, num)\
         NEG_USR32(name##_cache, num)
-- 
1.7.0




More information about the ffmpeg-devel mailing list