get_bits: add get_bits_le()

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/get_bits.h

@@ -139,27 +139,34 @@ typedef struct RL_VLC_ELEM {
 
 #define CLOSE_READER(name, gb) (gb)->index = name ## _index
 
+# ifdef LONG_BITSTREAM_READER
+
+# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
+      AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
+
+# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
+      AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))
+
+#else
+
+# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
+      AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
+
+# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
+      AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)
+
+#endif
+
+
 #ifdef BITSTREAM_READER_LE
 
-# ifdef LONG_BITSTREAM_READER
-#   define UPDATE_CACHE(name, gb) name ## _cache = \
-        AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
-# else
-#   define UPDATE_CACHE(name, gb) name ## _cache = \
-        AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
-# endif
+# define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb)
 
 # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num)
 
 #else
 
-# ifdef LONG_BITSTREAM_READER
-#   define UPDATE_CACHE(name, gb) name ## _cache = \
-        AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))
-# else
-#   define UPDATE_CACHE(name, gb) name ## _cache = \
-        AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)
-# endif
+# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)
 
 # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num)
 
@@ -180,12 +187,18 @@ typedef struct RL_VLC_ELEM {
 
 #define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 
+#define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num)
+#define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num)
+
+#define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num)
+#define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num)
+
 #ifdef BITSTREAM_READER_LE
-#   define SHOW_UBITS(name, gb, num) zero_extend(name ## _cache, num)
-#   define SHOW_SBITS(name, gb, num) sign_extend(name ## _cache, num)
+#   define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num)
+#   define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num)
 #else
-#   define SHOW_UBITS(name, gb, num) NEG_USR32(name ## _cache, num)
-#   define SHOW_SBITS(name, gb, num) NEG_SSR32(name ## _cache, num)
+#   define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)
+#   define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num)
 #endif
 
 #define GET_CACHE(name, gb) ((uint32_t) name ## _cache)
@@ -250,6 +263,18 @@ static inline unsigned int get_bits(GetBitContext *s, int n)
     return tmp;
 }
 
+static inline unsigned int get_bits_le(GetBitContext *s, int n)
+{
+    register int tmp;
+    OPEN_READER(re, s);
+    av_assert2(n>0 && n<=25);
+    UPDATE_CACHE_LE(re, s);
+    tmp = SHOW_UBITS_LE(re, s, n);
+    LAST_SKIP_BITS(re, s, n);
+    CLOSE_READER(re, s);
+    return tmp;
+}
+
 /**
  * Show 1-25 bits.
  */