Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavcodec/get_bits.h | 61 ++++++++++++++++++++++++++++++++++++++++---
1 file changed, 58 insertions(+), 3 deletions(-)
diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index 86cea00494a..806e4b16f49 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -668,13 +668,68 @@ static av_always_inline int get_vlc2(GetBitContext *s,
const VLCElem *table,
return code;
}
-static inline int get_vlc_multi(GetBitContext *s, uint8_t *dst,
+/**
+ * Parse a vlc / vlc_multi code.
+ * @param bits is the number of bits which will be read at once, must be
+ * identical to nb_bits in vlc_init(), should be known at compile
time
+ * @param max_depth is the number of times bits bits must be read to completely
+ * read the longest vlc code
+ * = (max_vlc_length + bits - 1) / bits
+ * @param dst the parsed symbol(s) will be stored here. Up to 8 bytes are
written
+ * @returns number of symbols parsed
+ * If the vlc code is invalid and max_depth=1, then no bits will be removed.
+ * If the vlc code is invalid and max_depth>1, then the number of bits removed
+ * is undefined.
+ */
+static inline int get_vlc_multi(GetBitContext *s, uint8_t * restrict dst,
const VLC_MULTI_ELEM *const Jtable,
const VLCElem *const table,
const int bits, const int max_depth)
{
- dst[0] = get_vlc2(s, table, bits, max_depth);
- return 1;
+ int ret, nb_bits, n;
+ unsigned int index;
+
+ OPEN_READER(re, s);
+ UPDATE_CACHE(re, s);
+
+ index = SHOW_UBITS(re, s, bits);
+ n = Jtable[index].len;
+ if (Jtable[index].num) {
+ AV_COPY64U(dst, Jtable[index].val);
+ ret = Jtable[index].num;
+ } else {
+ int code = table[index].sym;
+
+ if (av_builtin_constant_p(bits <= MIN_CACHE_BITS/2) && bits <=
MIN_CACHE_BITS/2) {
+ SKIP_BITS(re, s, bits);
+ } else {
+ LAST_SKIP_BITS(re, s, bits);
+ UPDATE_CACHE(re, s);
+ }
+
+ nb_bits = -n;
+
+ index = SHOW_UBITS(re, s, nb_bits) + code;
+ code = table[index].sym;
+ n = table[index].len;
+ if (max_depth > 2 && n < 0) {
+ LAST_SKIP_BITS(re, s, nb_bits);
+ UPDATE_CACHE(re, s);
+
+ nb_bits = -n;
+
+ index = SHOW_UBITS(re, s, nb_bits) + code;
+ code = table[index].sym;
+ n = table[index].len;
+ }
+ dst[0] = code;
+ ret = n > 0;
+ }
+ LAST_SKIP_BITS(re, s, n);
+
+ CLOSE_READER(re, s);
+
+ return ret;
}
static inline int decode012(GetBitContext *gb)
--
2.17.1
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