lavc/bitstream: templatize for BE/LE

Allows using both BE and LE bitstream readers in the same file.

3 files changed, 415 insertions, 357 deletions

diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h
index 85f1af28c8..3fa63695d3 100644
--- a/libavcodec/bitstream.h
+++ b/libavcodec/bitstream.h
@@ -49,88 +49,6 @@ typedef struct BitstreamContext {
     unsigned size_in_bits;
 } BitstreamContext;
 
-static inline void refill_64(BitstreamContext *bc)
-{
-#if !UNCHECKED_BITSTREAM_READER
-    if (bc->ptr >= bc->buffer_end)
-        return;
-#endif
-
-#ifdef BITSTREAM_READER_LE
-    bc->bits       = AV_RL64(bc->ptr);
-#else
-    bc->bits       = AV_RB64(bc->ptr);
-#endif
-    bc->ptr       += 8;
-    bc->bits_left  = 64;
-}
-
-static inline void refill_32(BitstreamContext *bc)
-{
-#if !UNCHECKED_BITSTREAM_READER
-    if (bc->ptr >= bc->buffer_end)
-        return;
-#endif
-
-#ifdef BITSTREAM_READER_LE
-    bc->bits       = (uint64_t)AV_RL32(bc->ptr) << bc->bits_left | bc->bits;
-#else
-    bc->bits       = bc->bits | (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_left);
-#endif
-    bc->ptr       += 4;
-    bc->bits_left += 32;
-}
-
-/**
- * Initialize BitstreamContext.
- * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
- *        larger than the actual read bits because some optimized bitstream
- *        readers read 32 or 64 bits at once and could read over the end
- * @param bit_size the size of the buffer in bits
- * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
- */
-static inline int bitstream_init(BitstreamContext *bc, const uint8_t *buffer,
-                                 unsigned int bit_size)
-{
-    unsigned int buffer_size;
-
-    if (bit_size > INT_MAX - 7 || !buffer) {
-        bc->buffer    = NULL;
-        bc->ptr       = NULL;
-        bc->bits_left = 0;
-        return AVERROR_INVALIDDATA;
-    }
-
-    buffer_size = (bit_size + 7) >> 3;
-
-    bc->buffer       = buffer;
-    bc->buffer_end   = buffer + buffer_size;
-    bc->ptr          = bc->buffer;
-    bc->size_in_bits = bit_size;
-    bc->bits_left    = 0;
-    bc->bits         = 0;
-
-    refill_64(bc);
-
-    return 0;
-}
-
-/**
- * Initialize BitstreamContext.
- * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
- *        larger than the actual read bits because some optimized bitstream
- *        readers read 32 or 64 bits at once and could read over the end
- * @param byte_size the size of the buffer in bytes
- * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow
- */
-static inline int bitstream_init8(BitstreamContext *bc, const uint8_t *buffer,
-                                  unsigned int byte_size)
-{
-    if (byte_size > INT_MAX / 8)
-        return AVERROR_INVALIDDATA;
-    return bitstream_init(bc, buffer, byte_size * 8);
-}
-
 /**
  * Return number of bits already read.
  */
@@ -155,235 +73,6 @@ static inline int bitstream_bits_left(const BitstreamContext *bc)
     return (bc->buffer - bc->ptr) * 8 + bc->size_in_bits + bc->bits_left;
 }
 
-static inline uint64_t get_val(BitstreamContext *bc, unsigned int n)
-{
-    uint64_t ret;
-
-#ifdef BITSTREAM_READER_LE
-    ret = bc->bits & ((UINT64_C(1) << n) - 1);
-    bc->bits >>= n;
-#else
-    ret = bc->bits >> (64 - n);
-    bc->bits <<= n;
-#endif
-    bc->bits_left -= n;
-
-    return ret;
-}
-
-/**
- * Return one bit from the buffer.
- */
-static inline unsigned int bitstream_read_bit(BitstreamContext *bc)
-{
-    if (!bc->bits_left)
-        refill_64(bc);
-
-    return get_val(bc, 1);
-}
-
-/**
- * Return n bits from the buffer, n has to be in the 0-63 range.
- */
-static inline uint64_t bitstream_read_63(BitstreamContext *bc, unsigned int n)
-{
-    uint64_t ret = 0;
-#ifdef BITSTREAM_READER_LE
-    uint64_t left = 0;
-#endif
-
-    if (!n)
-        return 0;
-
-    if (n > bc->bits_left) {
-        n -= bc->bits_left;
-#ifdef BITSTREAM_READER_LE
-        left = bc->bits_left;
-#endif
-        ret = get_val(bc, bc->bits_left);
-        refill_64(bc);
-    }
-
-#ifdef BITSTREAM_READER_LE
-    ret = get_val(bc, n) << left | ret;
-#else
-    ret = get_val(bc, n) | ret << n;
-#endif
-
-    return ret;
-}
-
-/**
- * Return n bits from the buffer, n has to be in the 0-32  range.
- */
-static inline uint32_t bitstream_read(BitstreamContext *bc, unsigned int n)
-{
-    if (!n)
-        return 0;
-
-    if (n > bc->bits_left) {
-        refill_32(bc);
-        if (bc->bits_left < 32)
-            bc->bits_left = n;
-    }
-
-    return get_val(bc, n);
-}
-
-/**
- * Return n bits from the buffer as a signed integer.
- * n has to be in the 0-32 range.
- */
-static inline int32_t bitstream_read_signed(BitstreamContext *bc, unsigned int n)
-{
-    return sign_extend(bitstream_read(bc, n), n);
-}
-
-static inline unsigned int show_val(BitstreamContext *bc, unsigned int n)
-{
-#ifdef BITSTREAM_READER_LE
-    return bc->bits & ((UINT64_C(1) << n) - 1);
-#else
-    return bc->bits >> (64 - n);
-#endif
-}
-
-/**
- * Return n bits from the buffer but do not change the buffer state.
- * n has to be in the 0-32 range.
- */
-static inline unsigned int bitstream_peek(BitstreamContext *bc, unsigned int n)
-{
-    if (n > bc->bits_left)
-        refill_32(bc);
-
-    return show_val(bc, n);
-}
-
-/**
- * Return n bits from the buffer as a signed integer,
- * do not change the buffer state.
- * n has to be in the 0-32 range.
- */
-static inline int bitstream_peek_signed(BitstreamContext *bc, unsigned int n)
-{
-    return sign_extend(bitstream_peek(bc, n), n);
-}
-
-static inline void skip_remaining(BitstreamContext *bc, unsigned int n)
-{
-#ifdef BITSTREAM_READER_LE
-    bc->bits >>= n;
-#else
-    bc->bits <<= n;
-#endif
-    bc->bits_left -= n;
-}
-
-/**
- * Skip n bits in the buffer.
- */
-static inline void bitstream_skip(BitstreamContext *bc, unsigned int n)
-{
-    if (n < bc->bits_left)
-        skip_remaining(bc, n);
-    else {
-        n -= bc->bits_left;
-        bc->bits      = 0;
-        bc->bits_left = 0;
-
-        if (n >= 64) {
-            unsigned int skip = n / 8;
-
-            n -= skip * 8;
-            bc->ptr += skip;
-        }
-        refill_64(bc);
-        if (n)
-            skip_remaining(bc, n);
-    }
-}
-
-/**
- * Seek to the given bit position.
- */
-static inline void bitstream_seek(BitstreamContext *bc, unsigned pos)
-{
-    bc->ptr       = bc->buffer;
-    bc->bits      = 0;
-    bc->bits_left = 0;
-
-    bitstream_skip(bc, pos);
-}
-
-/**
- * Skip bits to a byte boundary.
- */
-static inline const uint8_t *bitstream_align(BitstreamContext *bc)
-{
-    unsigned int n = -bitstream_tell(bc) & 7;
-    if (n)
-        bitstream_skip(bc, n);
-    return bc->buffer + (bitstream_tell(bc) >> 3);
-}
-
-/**
- * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
- * If MSB not set it is negative.
- * @param n length in bits
- */
-static inline int bitstream_read_xbits(BitstreamContext *bc, unsigned int n)
-{
-    int32_t cache = bitstream_peek(bc, 32);
-    int sign = ~cache >> 31;
-    skip_remaining(bc, n);
-
-    return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign;
-}
-
-/**
- * Return decoded truncated unary code for the values 0, 1, 2.
- */
-static inline int bitstream_decode012(BitstreamContext *bc)
-{
-    if (!bitstream_read_bit(bc))
-        return 0;
-    else
-        return bitstream_read_bit(bc) + 1;
-}
-
-/**
- * Return decoded truncated unary code for the values 2, 1, 0.
- */
-static inline int bitstream_decode210(BitstreamContext *bc)
-{
-    if (bitstream_read_bit(bc))
-        return 0;
-    else
-        return 2 - bitstream_read_bit(bc);
-}
-
-/* Read sign bit and flip the sign of the provided value accordingly. */
-static inline int bitstream_apply_sign(BitstreamContext *bc, int val)
-{
-    int sign = bitstream_read_signed(bc, 1);
-    return (val ^ sign) - sign;
-}
-
-static inline int bitstream_skip_1stop_8data(BitstreamContext *s)
-{
-    if (bitstream_bits_left(s) <= 0)
-        return AVERROR_INVALIDDATA;
-
-    while (bitstream_read(s, 1)) {
-        bitstream_skip(s, 8);
-        if (bitstream_bits_left(s) <= 0)
-            return AVERROR_INVALIDDATA;
-    }
-
-    return 0;
-}
-
 /* Unwind the cache so a refill_32 can fill it again. */
 static inline void bitstream_unwind(BitstreamContext *bc)
 {
@@ -412,52 +101,28 @@ static inline void bitstream_unget(BitstreamContext *bc, uint64_t value,
     bc->bits_left += amount;
 }
 
-/**
- * Return the LUT element for the given bitstream configuration.
- */
-static inline int set_idx(BitstreamContext *bc, int code, int *n, int *nb_bits,
-                          VLC_TYPE (*table)[2])
-{
-    unsigned idx;
-
-    *nb_bits = -*n;
-    idx = bitstream_peek(bc, *nb_bits) + code;
-    *n = table[idx][1];
-
-    return table[idx][0];
-}
-
-/**
- * Parse a vlc code.
- * @param bits is the number of bits which will be read at once, must be
- *             identical to nb_bits in init_vlc()
- * @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
- * 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 bitstream_read_vlc(BitstreamContext *bc, VLC_TYPE (*table)[2],
-                                     int bits, int max_depth)
-{
-    int nb_bits;
-    unsigned idx = bitstream_peek(bc, bits);
-    int code     = table[idx][0];
-    int n        = table[idx][1];
-
-    if (max_depth > 1 && n < 0) {
-        skip_remaining(bc, bits);
-        code = set_idx(bc, code, &n, &nb_bits, table);
-        if (max_depth > 2 && n < 0) {
-            skip_remaining(bc, nb_bits);
-            code = set_idx(bc, code, &n, &nb_bits, table);
-        }
-    }
-    skip_remaining(bc, n);
-
-    return code;
-}
+#define BITSTREAM_LE
+#include "bitstream_template.h"
+
+#undef BITSTREAM_LE
+#include "bitstream_template.h"
+
+#define bitstream_init          bitstream_init_be
+#define bitstream_init8         bitstream_init8_be
+#define bitstream_read_bit      bitstream_read_bit_be
+#define bitstream_read_63       bitstream_read_63_be
+#define bitstream_read          bitstream_read_be
+#define bitstream_read_signed   bitstream_read_signed_be
+#define bitstream_peek          bitstream_peek_be
+#define bitstream_peek_signed   bitstream_peek_signed_be
+#define bitstream_skip          bitstream_skip_be
+#define bitstream_seek          bitstream_seek_be
+#define bitstream_align         bitstream_align_be
+#define bitstream_read_xbits    bitstream_read_xbits_be
+#define bitstream_decode012     bitstream_decode012_be
+#define bitstream_decode210     bitstream_decode210_be
+#define bitstream_apply_sign    bitstream_apply_sign_be
+#define bitstream_read_vlc      bitstream_read_vlc_be
 
 #define BITSTREAM_RL_VLC(level, run, bc, table, bits, max_depth) \
     do {                                                         \
diff --git a/libavcodec/bitstream_template.h b/libavcodec/bitstream_template.h
new file mode 100644
index 0000000000..14a420139c
--- /dev/null
+++ b/libavcodec/bitstream_template.h
@@ -0,0 +1,392 @@
+/*
+ * Copyright (c) 2016 Alexandra Hájková
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifdef BITSTREAM_LE
+#   define BS_SUFFIX le
+#else
+#   define BS_SUFFIX be
+#endif
+
+#define BS_JOIN(x, y) x ## _ ## y
+#define BS_FUNC2(x, y) BS_JOIN(x, y)
+#define BS_FUNC(x) BS_FUNC2(x, BS_SUFFIX)
+
+static inline void BS_FUNC(refill_64)(BitstreamContext *bc)
+{
+#if !UNCHECKED_BITSTREAM_READER
+    if (bc->ptr >= bc->buffer_end)
+        return;
+#endif
+
+#ifdef BITSTREAM_LE
+    bc->bits       = AV_RL64(bc->ptr);
+#else
+    bc->bits       = AV_RB64(bc->ptr);
+#endif
+    bc->ptr       += 8;
+    bc->bits_left  = 64;
+}
+
+static inline void BS_FUNC(refill_32)(BitstreamContext *bc)
+{
+#if !UNCHECKED_BITSTREAM_READER
+    if (bc->ptr >= bc->buffer_end)
+        return;
+#endif
+
+#ifdef BITSTREAM_LE
+    bc->bits       = (uint64_t)AV_RL32(bc->ptr) << bc->bits_left | bc->bits;
+#else
+    bc->bits       = bc->bits | (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_left);
+#endif
+    bc->ptr       += 4;
+    bc->bits_left += 32;
+}
+
+/**
+ * Initialize BitstreamContext.
+ * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
+ *        larger than the actual read bits because some optimized bitstream
+ *        readers read 32 or 64 bits at once and could read over the end
+ * @param bit_size the size of the buffer in bits
+ * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
+ */
+static inline int BS_FUNC(bitstream_init)(BitstreamContext *bc, const uint8_t *buffer,
+                                          unsigned int bit_size)
+{
+    unsigned int buffer_size;
+
+    if (bit_size > INT_MAX - 7 || !buffer) {
+        bc->buffer    = NULL;
+        bc->ptr       = NULL;
+        bc->bits_left = 0;
+        return AVERROR_INVALIDDATA;
+    }
+
+    buffer_size = (bit_size + 7) >> 3;
+
+    bc->buffer       = buffer;
+    bc->buffer_end   = buffer + buffer_size;
+    bc->ptr          = bc->buffer;
+    bc->size_in_bits = bit_size;
+    bc->bits_left    = 0;
+    bc->bits         = 0;
+
+    BS_FUNC(refill_64)(bc);
+
+    return 0;
+}
+
+/**
+ * Initialize BitstreamContext.
+ * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
+ *        larger than the actual read bits because some optimized bitstream
+ *        readers read 32 or 64 bits at once and could read over the end
+ * @param byte_size the size of the buffer in bytes
+ * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow
+ */
+static inline int BS_FUNC(bitstream_init8)(BitstreamContext *bc, const uint8_t *buffer,
+                                           unsigned int byte_size)
+{
+    if (byte_size > INT_MAX / 8)
+        return AVERROR_INVALIDDATA;
+    return BS_FUNC(bitstream_init)(bc, buffer, byte_size * 8);
+}
+
+static inline uint64_t BS_FUNC(get_val)(BitstreamContext *bc, unsigned int n)
+{
+    uint64_t ret;
+
+#ifdef BITSTREAM_LE
+    ret = bc->bits & ((UINT64_C(1) << n) - 1);
+    bc->bits >>= n;
+#else
+    ret = bc->bits >> (64 - n);
+    bc->bits <<= n;
+#endif
+    bc->bits_left -= n;
+
+    return ret;
+}
+
+/**
+ * Return one bit from the buffer.
+ */
+static inline unsigned int BS_FUNC(bitstream_read_bit)(BitstreamContext *bc)
+{
+    if (!bc->bits_left)
+        BS_FUNC(refill_64)(bc);
+
+    return BS_FUNC(get_val)(bc, 1);
+}
+
+/**
+ * Return n bits from the buffer, n has to be in the 0-63 range.
+ */
+static inline uint64_t BS_FUNC(bitstream_read_63)(BitstreamContext *bc, unsigned int n)
+{
+    uint64_t ret = 0;
+#ifdef BITSTREAM_LE
+    uint64_t left = 0;
+#endif
+
+    if (!n)
+        return 0;
+
+    if (n > bc->bits_left) {
+        n -= bc->bits_left;
+#ifdef BITSTREAM_LE
+        left = bc->bits_left;
+#endif
+        ret = BS_FUNC(get_val)(bc, bc->bits_left);
+        BS_FUNC(refill_64)(bc);
+    }
+
+#ifdef BITSTREAM_LE
+    ret = get_val_le(bc, n) << left | ret;
+#else
+    ret = get_val_be(bc, n) | ret << n;
+#endif
+
+    return ret;
+}
+
+/**
+ * Return n bits from the buffer, n has to be in the 0-32  range.
+ */
+static inline uint32_t BS_FUNC(bitstream_read)(BitstreamContext *bc, unsigned int n)
+{
+    if (!n)
+        return 0;
+
+    if (n > bc->bits_left) {
+        BS_FUNC(refill_32)(bc);
+        if (bc->bits_left < 32)
+            bc->bits_left = n;
+    }
+
+    return BS_FUNC(get_val)(bc, n);
+}
+
+/**
+ * Return n bits from the buffer as a signed integer.
+ * n has to be in the 0-32 range.
+ */
+static inline int32_t BS_FUNC(bitstream_read_signed)(BitstreamContext *bc, unsigned int n)
+{
+    return sign_extend(BS_FUNC(bitstream_read)(bc, n), n);
+}
+
+static inline unsigned int BS_FUNC(show_val)(BitstreamContext *bc, unsigned int n)
+{
+#ifdef BITSTREAM_LE
+    return bc->bits & ((UINT64_C(1) << n) - 1);
+#else
+    return bc->bits >> (64 - n);
+#endif
+}
+
+/**
+ * Return n bits from the buffer but do not change the buffer state.
+ * n has to be in the 0-32 range.
+ */
+static inline unsigned int BS_FUNC(bitstream_peek)(BitstreamContext *bc, unsigned int n)
+{
+    if (n > bc->bits_left)
+        BS_FUNC(refill_32)(bc);
+
+    return BS_FUNC(show_val)(bc, n);
+}
+
+/**
+ * Return n bits from the buffer as a signed integer,
+ * do not change the buffer state.
+ * n has to be in the 0-32 range.
+ */
+static inline int BS_FUNC(bitstream_peek_signed)(BitstreamContext *bc, unsigned int n)
+{
+    return sign_extend(BS_FUNC(bitstream_peek)(bc, n), n);
+}
+
+static inline void BS_FUNC(skip_remaining)(BitstreamContext *bc, unsigned int n)
+{
+#ifdef BITSTREAM_LE
+    bc->bits >>= n;
+#else
+    bc->bits <<= n;
+#endif
+    bc->bits_left -= n;
+}
+
+/**
+ * Skip n bits in the buffer.
+ */
+static inline void BS_FUNC(bitstream_skip)(BitstreamContext *bc, unsigned int n)
+{
+    if (n < bc->bits_left)
+        BS_FUNC(skip_remaining)(bc, n);
+    else {
+        n -= bc->bits_left;
+        bc->bits      = 0;
+        bc->bits_left = 0;
+
+        if (n >= 64) {
+            unsigned int skip = n / 8;
+
+            n -= skip * 8;
+            bc->ptr += skip;
+        }
+        BS_FUNC(refill_64)(bc);
+        if (n)
+            BS_FUNC(skip_remaining)(bc, n);
+    }
+}
+
+/**
+ * Seek to the given bit position.
+ */
+static inline void BS_FUNC(bitstream_seek)(BitstreamContext *bc, unsigned pos)
+{
+    bc->ptr       = bc->buffer;
+    bc->bits      = 0;
+    bc->bits_left = 0;
+
+    BS_FUNC(bitstream_skip)(bc, pos);
+}
+
+/**
+ * Skip bits to a byte boundary.
+ */
+static inline const uint8_t *BS_FUNC(bitstream_align)(BitstreamContext *bc)
+{
+    unsigned int n = -bitstream_tell(bc) & 7;
+    if (n)
+        BS_FUNC(bitstream_skip)(bc, n);
+    return bc->buffer + (bitstream_tell(bc) >> 3);
+}
+
+/**
+ * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
+ * If MSB not set it is negative.
+ * @param n length in bits
+ */
+static inline int BS_FUNC(bitstream_read_xbits)(BitstreamContext *bc, unsigned int n)
+{
+    int32_t cache = BS_FUNC(bitstream_peek)(bc, 32);
+    int sign = ~cache >> 31;
+    BS_FUNC(skip_remaining)(bc, n);
+
+    return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign;
+}
+
+/**
+ * Return decoded truncated unary code for the values 0, 1, 2.
+ */
+static inline int BS_FUNC(bitstream_decode012)(BitstreamContext *bc)
+{
+    if (!BS_FUNC(bitstream_read_bit)(bc))
+        return 0;
+    else
+        return BS_FUNC(bitstream_read_bit)(bc) + 1;
+}
+
+/**
+ * Return decoded truncated unary code for the values 2, 1, 0.
+ */
+static inline int BS_FUNC(bitstream_decode210)(BitstreamContext *bc)
+{
+    if (BS_FUNC(bitstream_read_bit)(bc))
+        return 0;
+    else
+        return 2 - BS_FUNC(bitstream_read_bit)(bc);
+}
+
+/* Read sign bit and flip the sign of the provided value accordingly. */
+static inline int BS_FUNC(bitstream_apply_sign)(BitstreamContext *bc, int val)
+{
+    int sign = BS_FUNC(bitstream_read_signed)(bc, 1);
+    return (val ^ sign) - sign;
+}
+
+static inline int BS_FUNC(bitstream_skip_1stop_8data)(BitstreamContext *s)
+{
+    if (bitstream_bits_left(s) <= 0)
+        return AVERROR_INVALIDDATA;
+
+    while (BS_FUNC(bitstream_read)(s, 1)) {
+        BS_FUNC(bitstream_skip)(s, 8);
+        if (bitstream_bits_left(s) <= 0)
+            return AVERROR_INVALIDDATA;
+    }
+
+    return 0;
+}
+
+/**
+ * Return the LUT element for the given bitstream configuration.
+ */
+static inline int BS_FUNC(set_idx)(BitstreamContext *bc, int code, int *n, int *nb_bits,
+                                   VLC_TYPE (*table)[2])
+{
+    unsigned idx;
+
+    *nb_bits = -*n;
+    idx = BS_FUNC(bitstream_peek)(bc, *nb_bits) + code;
+    *n = table[idx][1];
+
+    return table[idx][0];
+}
+
+/**
+ * Parse a vlc code.
+ * @param bits is the number of bits which will be read at once, must be
+ *             identical to nb_bits in init_vlc()
+ * @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
+ * 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 BS_FUNC(bitstream_read_vlc)(BitstreamContext *bc, VLC_TYPE (*table)[2],
+                                              int bits, int max_depth)
+{
+    int nb_bits;
+    unsigned idx = BS_FUNC(bitstream_peek)(bc, bits);
+    int code     = table[idx][0];
+    int n        = table[idx][1];
+
+    if (max_depth > 1 && n < 0) {
+        BS_FUNC(skip_remaining)(bc, bits);
+        code = BS_FUNC(set_idx)(bc, code, &n, &nb_bits, table);
+        if (max_depth > 2 && n < 0) {
+            BS_FUNC(skip_remaining)(bc, nb_bits);
+            code = BS_FUNC(set_idx)(bc, code, &n, &nb_bits, table);
+        }
+    }
+    BS_FUNC(skip_remaining)(bc, n);
+
+    return code;
+}
+
+#undef BS_FUNC
+#undef BS_FUNC2
+#undef BS_JOIN
+#undef BS_SUFFIX
diff --git a/tests/ref/fate/source b/tests/ref/fate/source
index 69dcdc4f27..497f296196 100644
--- a/tests/ref/fate/source
+++ b/tests/ref/fate/source
@@ -20,6 +20,7 @@ Headers without standard inclusion guards:
 compat/djgpp/math.h
 compat/float/float.h
 compat/float/limits.h
+libavcodec/bitstream_template.h
 tools/decode_simple.h
 Use of av_clip() where av_clip_uintp2() could be used:
 Use of av_clip() where av_clip_intp2() could be used: