lavc/bitstream: templatize for BE/LE

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

4 files changed, 611 insertions, 450 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 3ab448dd49..68669b1b46 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1252,6 +1252,7 @@ SKIPHEADERS                            += %_tablegen.h                  \
                                           aaccoder_trellis.h            \
                                           aacenc_quantization.h         \
                                           aacenc_quantization_misc.h    \
+                                          bitstream_template.h          \
                                           $(ARCH)/vpx_arith.h          \
 
 SKIPHEADERS-$(CONFIG_AMF)              += amfenc.h
diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h
index 6fd321dba5..ef7d8d55c2 100644
--- a/libavcodec/bitstream.h
+++ b/libavcodec/bitstream.h
@@ -23,6 +23,21 @@
  * bitstream reader API header.
  */
 
+/*
+ * Bit order (endianness) is controlled by #defining BITSTREAM_BE and/or
+ * BITSTREAM_LE before #including this header. The corresponding bitreading
+ * functions are provided as bits_*_be()/bits_*_le() respectively.
+ *
+ * If neither or only BITSTREAM_BE is defined, then the default (unsuffixed)
+ * bits_*() will resolve to the big-endian implementation. If only BITSTREAM_LE
+ * is defined, little-endian will be the default.
+ *
+ * If both are defined, then the default can be controlled by defining at most
+ * one of BITSTREAM_DEFAULT_LE/BE. When BITSTREAM_DEFAULT_* is not defined, no
+ * default is provided and you must always explicitly use the _be() or _le()
+ * variants.
+ */
+
 #ifndef AVCODEC_BITSTREAM_H
 #define AVCODEC_BITSTREAM_H
 
@@ -42,461 +57,80 @@
 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
 #endif
 
-typedef struct BitstreamContext {
-    uint64_t bits;       // stores bits read from the buffer
-    const uint8_t *buffer, *buffer_end;
-    const uint8_t *ptr;  // pointer to the position inside a buffer
-    unsigned bits_valid; // number of bits left in bits field
-    unsigned size_in_bits;
-} BitstreamContext;
-
-/**
- * @return
- * - 0 on successful refill
- * - a negative number when bitstream end is hit
- *
- * Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
- */
-static inline int bits_priv_refill_64(BitstreamContext *bc)
-{
-#if !UNCHECKED_BITSTREAM_READER
-    if (bc->ptr >= bc->buffer_end)
-        return -1;
-#endif
-
-#ifdef BITSTREAM_READER_LE
-    bc->bits       = AV_RL64(bc->ptr);
-#else
-    bc->bits       = AV_RB64(bc->ptr);
-#endif
-    bc->ptr       += 8;
-    bc->bits_valid = 64;
-
-    return 0;
-}
-
-/**
- * @return
- * - 0 on successful refill
- * - a negative number when bitstream end is hit
- *
- * Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
- */
-static inline int bits_priv_refill_32(BitstreamContext *bc)
-{
-#if !UNCHECKED_BITSTREAM_READER
-    if (bc->ptr >= bc->buffer_end)
-        return -1;
-#endif
-
-#ifdef BITSTREAM_READER_LE
-    bc->bits      |= (uint64_t)AV_RL32(bc->ptr) << bc->bits_valid;
-#else
-    bc->bits      |= (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_valid);
-#endif
-    bc->ptr        += 4;
-    bc->bits_valid += 32;
-
-    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 bit_size the size of the buffer in bits
- * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
- */
-static inline int bits_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_valid = 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_valid   = 0;
-    bc->bits         = 0;
-
-    bits_priv_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 bits_init8(BitstreamContext *bc, const uint8_t *buffer,
-                             unsigned int byte_size)
-{
-    if (byte_size > INT_MAX / 8)
-        return AVERROR_INVALIDDATA;
-    return bits_init(bc, buffer, byte_size * 8);
-}
-
-/**
- * Return number of bits already read.
- */
-static inline int bits_tell(const BitstreamContext *bc)
-{
-    return (bc->ptr - bc->buffer) * 8 - bc->bits_valid;
-}
-
-/**
- * Return buffer size in bits.
- */
-static inline int bits_size(const BitstreamContext *bc)
-{
-    return bc->size_in_bits;
-}
-
-/**
- * Return the number of the bits left in a buffer.
- */
-static inline int bits_left(const BitstreamContext *bc)
-{
-    return (bc->buffer - bc->ptr) * 8 + bc->size_in_bits + bc->bits_valid;
-}
-
-static inline uint64_t bits_priv_val_show(BitstreamContext *bc, unsigned int n)
-{
-    av_assert2(n > 0 && n <= 64);
-
-#ifdef BITSTREAM_READER_LE
-    return bc->bits & (UINT64_MAX >> (64 - n));
-#else
-    return bc->bits >> (64 - n);
-#endif
-}
-
-static inline void bits_priv_skip_remaining(BitstreamContext *bc, unsigned int n)
-{
-#ifdef BITSTREAM_READER_LE
-    bc->bits >>= n;
-#else
-    bc->bits <<= n;
-#endif
-    bc->bits_valid -= n;
-}
-
-static inline uint64_t bits_priv_val_get(BitstreamContext *bc, unsigned int n)
-{
-    uint64_t ret;
-
-    av_assert2(n > 0 && n < 64);
-
-    ret = bits_priv_val_show(bc, n);
-    bits_priv_skip_remaining(bc, n);
-
-    return ret;
-}
-
-/**
- * Return one bit from the buffer.
- */
-static inline unsigned int bits_read_bit(BitstreamContext *bc)
-{
-    if (!bc->bits_valid && bits_priv_refill_64(bc) < 0)
-        return 0;
-
-    return bits_priv_val_get(bc, 1);
-}
-
-/**
- * Return n bits from the buffer, n has to be in the 1-32 range.
- * May be faster than bits_read() when n is not a compile-time constant and is
- * known to be non-zero;
- */
-static inline uint32_t bits_read_nz(BitstreamContext *bc, unsigned int n)
-{
-    av_assert2(n > 0 && n <= 32);
-
-    if (n > bc->bits_valid) {
-        if (bits_priv_refill_32(bc) < 0)
-            bc->bits_valid = n;
-    }
-
-    return bits_priv_val_get(bc, n);
-}
-
-/**
- * Return n bits from the buffer, n has to be in the 0-32  range.
- */
-static inline uint32_t bits_read(BitstreamContext *bc, unsigned int n)
-{
-    av_assert2(n <= 32);
-
-    if (!n)
-        return 0;
-
-    return bits_read_nz(bc, n);
-}
-
-/**
- * Return n bits from the buffer, n has to be in the 0-63 range.
- */
-static inline uint64_t bits_read_63(BitstreamContext *bc, unsigned int n)
-{
-    uint64_t ret = 0;
-    unsigned left = 0;
-
-    av_assert2(n <= 63);
-
-    if (!n)
-        return 0;
-
-    if (n > bc->bits_valid) {
-        left = bc->bits_valid;
-        n   -= left;
-
-        if (left)
-            ret = bits_priv_val_get(bc, left);
-
-        if (bits_priv_refill_64(bc) < 0)
-            bc->bits_valid = n;
-
-    }
-
-#ifdef BITSTREAM_READER_LE
-    ret = bits_priv_val_get(bc, n) << left | ret;
-#else
-    ret = bits_priv_val_get(bc, n) | ret << n;
+// select the default endianness, if any
+#if defined(BITSTREAM_LE) && defined(BITSTREAM_BE)
+
+# if defined(BITSTREAM_DEFAULT_BE) && defined(BITSTREAM_DEFAULT_LE)
+#  error "At most one of BITSTREAM_DEFAULT_BE/LE must be defined"
+# elif   defined(BITSTREAM_DEFAULT_BE)
+#  define BITS_DEFAULT_BE
+# elif   defined(BITSTREAM_DEFAULT_LE)
+#  define BITS_DEFAULT_LE
+# endif
+
+#elif defined(BITSTREAM_LE)
+# define BITS_DEFAULT_LE
+#else // select BE if nothing is requested explicitly
+# define BITS_DEFAULT_BE
+# define BITSTREAM_WANT_BE
 #endif
 
-    return ret;
-}
+#if defined(BITS_DEFAULT_LE)
+
+# define BitstreamContext   BitstreamContextLE
+# define bits_init          bits_init_le
+# define bits_init8         bits_init8_le
+# define bits_tell          bits_tell_le
+# define bits_size          bits_size_le
+# define bits_left          bits_left_le
+# define bits_read_bit      bits_read_bit_le
+# define bits_read_nz       bits_read_nz_le
+# define bits_read          bits_read_le
+# define bits_read_63       bits_read_63_le
+# define bits_read_64       bits_read_64_le
+# define bits_read_signed   bits_read_signed_le
+# define bits_peek_nz       bits_peek_nz_le
+# define bits_peek          bits_peek_le
+# define bits_peek_signed   bits_peek_signed_le
+# define bits_skip          bits_skip_le
+# define bits_seek          bits_seek_le
+# define bits_align         bits_align_le
+# define bits_read_xbits    bits_read_xbits_le
+# define bits_decode012     bits_decode012_le
+# define bits_decode210     bits_decode210_le
+# define bits_apply_sign    bits_apply_sign_le
+# define bits_read_vlc      bits_read_vlc_le
+
+#elif defined(BITS_DEFAULT_BE)
+
+# define BitstreamContext   BitstreamContextBE
+# define bits_init          bits_init_be
+# define bits_init8         bits_init8_be
+# define bits_tell          bits_tell_be
+# define bits_size          bits_size_be
+# define bits_left          bits_left_be
+# define bits_read_bit      bits_read_bit_be
+# define bits_read_nz       bits_read_nz_be
+# define bits_read          bits_read_be
+# define bits_read_63       bits_read_63_be
+# define bits_read_64       bits_read_64_be
+# define bits_read_signed   bits_read_signed_be
+# define bits_peek_nz       bits_peek_nz_be
+# define bits_peek          bits_peek_be
+# define bits_peek_signed   bits_peek_signed_be
+# define bits_skip          bits_skip_be
+# define bits_seek          bits_seek_be
+# define bits_align         bits_align_be
+# define bits_read_xbits    bits_read_xbits_be
+# define bits_decode012     bits_decode012_be
+# define bits_decode210     bits_decode210_be
+# define bits_apply_sign    bits_apply_sign_be
+# define bits_read_vlc      bits_read_vlc_be
 
-/**
- * Return n bits from the buffer, n has to be in the 0-64 range.
- */
-static inline uint64_t bits_read_64(BitstreamContext *bc, unsigned int n)
-{
-    av_assert2(n <= 64);
-
-    if (n == 64) {
-        uint64_t ret = bits_read_63(bc, 63);
-#ifdef BITSTREAM_READER_LE
-        return ret | ((uint64_t)bits_read_bit(bc) << 63);
-#else
-        return (ret << 1) | (uint64_t)bits_read_bit(bc);
 #endif
-    }
-    return bits_read_63(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 bits_read_signed(BitstreamContext *bc, unsigned int n)
-{
-    return sign_extend(bits_read(bc, n), n);
-}
-
-/**
- * Return n bits from the buffer but do not change the buffer state.
- * n has to be in the 1-32 range. May
- */
-static inline uint32_t bits_peek_nz(BitstreamContext *bc, unsigned int n)
-{
-    av_assert2(n > 0 && n <= 32);
-
-    if (n > bc->bits_valid)
-        bits_priv_refill_32(bc);
-
-    return bits_priv_val_show(bc, n);
-}
-
-/**
- * Return n bits from the buffer but do not change the buffer state.
- * n has to be in the 0-32 range.
- */
-static inline uint32_t bits_peek(BitstreamContext *bc, unsigned int n)
-{
-    av_assert2(n <= 32);
-
-    if (!n)
-        return 0;
 
-    return bits_peek_nz(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 bits_peek_signed(BitstreamContext *bc, unsigned int n)
-{
-    return sign_extend(bits_peek(bc, n), n);
-}
-
-/**
- * Skip n bits in the buffer.
- */
-static inline void bits_skip(BitstreamContext *bc, unsigned int n)
-{
-    if (n < bc->bits_valid)
-        bits_priv_skip_remaining(bc, n);
-    else {
-        n -= bc->bits_valid;
-        bc->bits       = 0;
-        bc->bits_valid = 0;
-
-        if (n >= 64) {
-            unsigned int skip = n / 8;
-
-            n -= skip * 8;
-            bc->ptr += skip;
-        }
-        bits_priv_refill_64(bc);
-        if (n)
-            bits_priv_skip_remaining(bc, n);
-    }
-}
-
-/**
- * Seek to the given bit position.
- */
-static inline void bits_seek(BitstreamContext *bc, unsigned pos)
-{
-    bc->ptr        = bc->buffer;
-    bc->bits       = 0;
-    bc->bits_valid = 0;
-
-    bits_skip(bc, pos);
-}
-
-/**
- * Skip bits to a byte boundary.
- */
-static inline const uint8_t *bits_align(BitstreamContext *bc)
-{
-    unsigned int n = -bits_tell(bc) & 7;
-    if (n)
-        bits_skip(bc, n);
-    return bc->buffer + (bits_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 bits_read_xbits(BitstreamContext *bc, unsigned int n)
-{
-    int32_t cache = bits_peek(bc, 32);
-    int sign = ~cache >> 31;
-    bits_priv_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 bits_decode012(BitstreamContext *bc)
-{
-    if (!bits_read_bit(bc))
-        return 0;
-    else
-        return bits_read_bit(bc) + 1;
-}
-
-/**
- * Return decoded truncated unary code for the values 2, 1, 0.
- */
-static inline int bits_decode210(BitstreamContext *bc)
-{
-    if (bits_read_bit(bc))
-        return 0;
-    else
-        return 2 - bits_read_bit(bc);
-}
-
-/* Read sign bit and flip the sign of the provided value accordingly. */
-static inline int bits_apply_sign(BitstreamContext *bc, int val)
-{
-    int sign = bits_read_signed(bc, 1);
-    return (val ^ sign) - sign;
-}
-
-static inline int bits_skip_1stop_8data(BitstreamContext *s)
-{
-    if (bits_left(s) <= 0)
-        return AVERROR_INVALIDDATA;
-
-    while (bits_read_bit(s)) {
-        bits_skip(s, 8);
-        if (bits_left(s) <= 0)
-            return AVERROR_INVALIDDATA;
-    }
-
-    return 0;
-}
-
-/**
- * Return the LUT element for the given bitstream configuration.
- */
-static inline int bits_priv_set_idx(BitstreamContext *bc, int code, int *n, int *nb_bits,
-                                    const VLCElem *table)
-{
-    unsigned idx;
-
-    *nb_bits = -*n;
-    idx = bits_peek(bc, *nb_bits) + code;
-    *n = table[idx].len;
-
-    return table[idx].sym;
-}
-
-/**
- * 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 bits_read_vlc(BitstreamContext *bc, const VLCElem *table,
-                                int bits, int max_depth)
-{
-    int nb_bits;
-    unsigned idx = bits_peek(bc, bits);
-    int code     = table[idx].sym;
-    int n        = table[idx].len;
-
-    if (max_depth > 1 && n < 0) {
-        bits_priv_skip_remaining(bc, bits);
-        code = bits_priv_set_idx(bc, code, &n, &nb_bits, table);
-        if (max_depth > 2 && n < 0) {
-            bits_priv_skip_remaining(bc, nb_bits);
-            code = bits_priv_set_idx(bc, code, &n, &nb_bits, table);
-        }
-    }
-    bits_priv_skip_remaining(bc, n);
-
-    return code;
-}
+#undef BITS_DEFAULT_LE
+#undef BITS_DEFAULT_BE
 
 #define BITS_RL_VLC(level, run, bc, table, bits, max_depth) \
     do {                                                    \
@@ -527,3 +161,32 @@ static inline int bits_read_vlc(BitstreamContext *bc, const VLCElem *table,
     } while (0)
 
 #endif /* AVCODEC_BITSTREAM_H */
+
+// the following is deliberately outside of the standard #include guards
+
+#if  defined(BITSTREAM_LE) && !defined(BITSTREAM_WANT_LE)
+# define BITSTREAM_WANT_LE
+#endif
+
+#if defined(BITSTREAM_BE) && !defined(BITSTREAM_WANT_BE)
+# define BITSTREAM_WANT_BE
+#endif
+
+#if defined(BITSTREAM_WANT_LE) && !defined(AVCODEC_BITSTREAM_LE)
+#define AVCODEC_BITSTREAM_LE
+
+#define BITSTREAM_TEMPLATE_LE
+#include "bitstream_template.h"
+#undef BITSTREAM_TEMPLATE_LE
+
+#endif
+
+#if defined(BITSTREAM_WANT_BE) && !defined(AVCODEC_BITSTREAM_BE)
+#define AVCODEC_BITSTREAM_BE
+
+#include "bitstream_template.h"
+
+#endif
+
+#undef BITSTREAM_WANT_LE
+#undef BITSTREAM_WANT_BE
diff --git a/libavcodec/bitstream_template.h b/libavcodec/bitstream_template.h
new file mode 100644
index 0000000000..f2c14fc4d3
--- /dev/null
+++ b/libavcodec/bitstream_template.h
@@ -0,0 +1,496 @@
+/*
+ * 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_TEMPLATE_LE
+#   define BS_SUFFIX_LOWER _le
+#   define BS_SUFFIX_UPPER LE
+#else
+#   define BS_SUFFIX_LOWER _be
+#   define BS_SUFFIX_UPPER BE
+#endif
+
+#define BS_JOIN(x, y, z) x ## y ## z
+#define BS_JOIN3(x, y, z) BS_JOIN(x, y, z)
+#define BS_FUNC(x) BS_JOIN3(bits_, x, BS_SUFFIX_LOWER)
+
+#define BSCTX BS_JOIN3(Bitstream, Context, BS_SUFFIX_UPPER)
+
+typedef struct BSCTX {
+    uint64_t bits;       // stores bits read from the buffer
+    const uint8_t *buffer, *buffer_end;
+    const uint8_t *ptr;  // pointer to the position inside a buffer
+    unsigned bits_valid; // number of bits left in bits field
+    unsigned size_in_bits;
+} BSCTX;
+
+/**
+ * @return
+ * - 0 on successful refill
+ * - a negative number when bitstream end is hit
+ *
+ * Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
+ */
+static inline int BS_FUNC(priv_refill_64)(BSCTX *bc)
+{
+#if !UNCHECKED_BITSTREAM_READER
+    if (bc->ptr >= bc->buffer_end)
+        return -1;
+#endif
+
+#ifdef BITSTREAM_TEMPLATE_LE
+    bc->bits       = AV_RL64(bc->ptr);
+#else
+    bc->bits       = AV_RB64(bc->ptr);
+#endif
+    bc->ptr       += 8;
+    bc->bits_valid = 64;
+
+    return 0;
+}
+
+/**
+ * @return
+ * - 0 on successful refill
+ * - a negative number when bitstream end is hit
+ *
+ * Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
+ */
+static inline int BS_FUNC(priv_refill_32)(BSCTX *bc)
+{
+#if !UNCHECKED_BITSTREAM_READER
+    if (bc->ptr >= bc->buffer_end)
+        return -1;
+#endif
+
+#ifdef BITSTREAM_TEMPLATE_LE
+    bc->bits      |= (uint64_t)AV_RL32(bc->ptr) << bc->bits_valid;
+#else
+    bc->bits      |= (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_valid);
+#endif
+    bc->ptr        += 4;
+    bc->bits_valid += 32;
+
+    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 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(init)(BSCTX *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_valid = 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_valid   = 0;
+    bc->bits         = 0;
+
+    BS_FUNC(priv_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(init8)(BSCTX *bc, const uint8_t *buffer,
+                                      unsigned int byte_size)
+{
+    if (byte_size > INT_MAX / 8)
+        return AVERROR_INVALIDDATA;
+    return BS_FUNC(init)(bc, buffer, byte_size * 8);
+}
+
+/**
+ * Return number of bits already read.
+ */
+static inline int BS_FUNC(tell)(const BSCTX *bc)
+{
+    return (bc->ptr - bc->buffer) * 8 - bc->bits_valid;
+}
+
+/**
+ * Return buffer size in bits.
+ */
+static inline int BS_FUNC(size)(const BSCTX *bc)
+{
+    return bc->size_in_bits;
+}
+
+/**
+ * Return the number of the bits left in a buffer.
+ */
+static inline int BS_FUNC(left)(const BSCTX *bc)
+{
+    return (bc->buffer - bc->ptr) * 8 + bc->size_in_bits + bc->bits_valid;
+}
+
+static inline uint64_t BS_FUNC(priv_val_show)(BSCTX *bc, unsigned int n)
+{
+    av_assert2(n > 0 && n <= 64);
+
+#ifdef BITSTREAM_TEMPLATE_LE
+    return bc->bits & (UINT64_MAX >> (64 - n));
+#else
+    return bc->bits >> (64 - n);
+#endif
+}
+
+static inline void BS_FUNC(priv_skip_remaining)(BSCTX *bc, unsigned int n)
+{
+#ifdef BITSTREAM_TEMPLATE_LE
+    bc->bits >>= n;
+#else
+    bc->bits <<= n;
+#endif
+    bc->bits_valid -= n;
+}
+
+static inline uint64_t BS_FUNC(priv_val_get)(BSCTX *bc, unsigned int n)
+{
+    uint64_t ret;
+
+    av_assert2(n > 0 && n < 64);
+
+    ret = BS_FUNC(priv_val_show)(bc, n);
+    BS_FUNC(priv_skip_remaining)(bc, n);
+
+    return ret;
+}
+
+/**
+ * Return one bit from the buffer.
+ */
+static inline unsigned int BS_FUNC(read_bit)(BSCTX *bc)
+{
+    if (!bc->bits_valid && BS_FUNC(priv_refill_64)(bc) < 0)
+        return 0;
+
+    return BS_FUNC(priv_val_get)(bc, 1);
+}
+
+/**
+ * Return n bits from the buffer, n has to be in the 1-32 range.
+ * May be faster than bits_read() when n is not a compile-time constant and is
+ * known to be non-zero;
+ */
+static inline uint32_t BS_FUNC(read_nz)(BSCTX *bc, unsigned int n)
+{
+    av_assert2(n > 0 && n <= 32);
+
+    if (n > bc->bits_valid) {
+        if (BS_FUNC(priv_refill_32)(bc) < 0)
+            bc->bits_valid = n;
+    }
+
+    return BS_FUNC(priv_val_get)(bc, n);
+}
+
+/**
+ * Return n bits from the buffer, n has to be in the 0-32  range.
+ */
+static inline uint32_t BS_FUNC(read)(BSCTX *bc, unsigned int n)
+{
+    av_assert2(n <= 32);
+
+    if (!n)
+        return 0;
+
+    return BS_FUNC(read_nz)(bc, n);
+}
+
+/**
+ * Return n bits from the buffer, n has to be in the 0-63 range.
+ */
+static inline uint64_t BS_FUNC(read_63)(BSCTX *bc, unsigned int n)
+{
+    uint64_t ret = 0;
+    unsigned left = 0;
+
+    av_assert2(n <= 63);
+
+    if (!n)
+        return 0;
+
+    if (n > bc->bits_valid) {
+        left = bc->bits_valid;
+        n   -= left;
+
+        if (left)
+            ret = BS_FUNC(priv_val_get)(bc, left);
+
+        if (BS_FUNC(priv_refill_64)(bc) < 0)
+            bc->bits_valid = n;
+
+    }
+
+#ifdef BITSTREAM_TEMPLATE_LE
+    ret = BS_FUNC(priv_val_get)(bc, n) << left | ret;
+#else
+    ret = BS_FUNC(priv_val_get)(bc, n) | ret << n;
+#endif
+
+    return ret;
+}
+
+/**
+ * Return n bits from the buffer, n has to be in the 0-64 range.
+ */
+static inline uint64_t BS_FUNC(read_64)(BSCTX *bc, unsigned int n)
+{
+    av_assert2(n <= 64);
+
+    if (n == 64) {
+        uint64_t ret = BS_FUNC(read_63)(bc, 63);
+#ifdef BITSTREAM_TEMPLATE_LE
+        return ret | ((uint64_t)BS_FUNC(read_bit)(bc) << 63);
+#else
+        return (ret << 1) | (uint64_t)BS_FUNC(read_bit)(bc);
+#endif
+    }
+    return BS_FUNC(read_63)(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(read_signed)(BSCTX *bc, unsigned int n)
+{
+    return sign_extend(BS_FUNC(read)(bc, n), n);
+}
+
+/**
+ * Return n bits from the buffer but do not change the buffer state.
+ * n has to be in the 1-32 range. May
+ */
+static inline uint32_t BS_FUNC(peek_nz)(BSCTX *bc, unsigned int n)
+{
+    av_assert2(n > 0 && n <= 32);
+
+    if (n > bc->bits_valid)
+        BS_FUNC(priv_refill_32)(bc);
+
+    return BS_FUNC(priv_val_show)(bc, n);
+}
+
+/**
+ * Return n bits from the buffer but do not change the buffer state.
+ * n has to be in the 0-32 range.
+ */
+static inline uint32_t BS_FUNC(peek)(BSCTX *bc, unsigned int n)
+{
+    av_assert2(n <= 32);
+
+    if (!n)
+        return 0;
+
+    return BS_FUNC(peek_nz)(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(peek_signed)(BSCTX *bc, unsigned int n)
+{
+    return sign_extend(BS_FUNC(peek)(bc, n), n);
+}
+
+/**
+ * Skip n bits in the buffer.
+ */
+static inline void BS_FUNC(skip)(BSCTX *bc, unsigned int n)
+{
+    if (n < bc->bits_valid)
+        BS_FUNC(priv_skip_remaining)(bc, n);
+    else {
+        n -= bc->bits_valid;
+        bc->bits       = 0;
+        bc->bits_valid = 0;
+
+        if (n >= 64) {
+            unsigned int skip = n / 8;
+
+            n -= skip * 8;
+            bc->ptr += skip;
+        }
+        BS_FUNC(priv_refill_64)(bc);
+        if (n)
+            BS_FUNC(priv_skip_remaining)(bc, n);
+    }
+}
+
+/**
+ * Seek to the given bit position.
+ */
+static inline void BS_FUNC(seek)(BSCTX *bc, unsigned pos)
+{
+    bc->ptr        = bc->buffer;
+    bc->bits       = 0;
+    bc->bits_valid = 0;
+
+    BS_FUNC(skip)(bc, pos);
+}
+
+/**
+ * Skip bits to a byte boundary.
+ */
+static inline const uint8_t *BS_FUNC(align)(BSCTX *bc)
+{
+    unsigned int n = -BS_FUNC(tell)(bc) & 7;
+    if (n)
+        BS_FUNC(skip)(bc, n);
+    return bc->buffer + (BS_FUNC(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(read_xbits)(BSCTX *bc, unsigned int n)
+{
+    int32_t cache = BS_FUNC(peek)(bc, 32);
+    int sign = ~cache >> 31;
+    BS_FUNC(priv_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(decode012)(BSCTX *bc)
+{
+    if (!BS_FUNC(read_bit)(bc))
+        return 0;
+    else
+        return BS_FUNC(read_bit)(bc) + 1;
+}
+
+/**
+ * Return decoded truncated unary code for the values 2, 1, 0.
+ */
+static inline int BS_FUNC(decode210)(BSCTX *bc)
+{
+    if (BS_FUNC(read_bit)(bc))
+        return 0;
+    else
+        return 2 - BS_FUNC(read_bit)(bc);
+}
+
+/* Read sign bit and flip the sign of the provided value accordingly. */
+static inline int BS_FUNC(apply_sign)(BSCTX *bc, int val)
+{
+    int sign = BS_FUNC(read_signed)(bc, 1);
+    return (val ^ sign) - sign;
+}
+
+static inline int BS_FUNC(skip_1stop_8data)(BSCTX *s)
+{
+    if (BS_FUNC(left)(s) <= 0)
+        return AVERROR_INVALIDDATA;
+
+    while (BS_FUNC(read_bit)(s)) {
+        BS_FUNC(skip)(s, 8);
+        if (BS_FUNC(left)(s) <= 0)
+            return AVERROR_INVALIDDATA;
+    }
+
+    return 0;
+}
+
+/**
+ * Return the LUT element for the given bitstream configuration.
+ */
+static inline int BS_FUNC(priv_set_idx)(BSCTX *bc, int code, int *n,
+                                             int *nb_bits, const VLCElem *table)
+{
+    unsigned idx;
+
+    *nb_bits = -*n;
+    idx = BS_FUNC(peek)(bc, *nb_bits) + code;
+    *n = table[idx].len;
+
+    return table[idx].sym;
+}
+
+/**
+ * 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(read_vlc)(BSCTX *bc, const VLCElem *table,
+                                         int bits, int max_depth)
+{
+    int nb_bits;
+    unsigned idx = BS_FUNC(peek)(bc, bits);
+    int code     = table[idx].sym;
+    int n        = table[idx].len;
+
+    if (max_depth > 1 && n < 0) {
+        BS_FUNC(priv_skip_remaining)(bc, bits);
+        code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
+        if (max_depth > 2 && n < 0) {
+            BS_FUNC(priv_skip_remaining)(bc, nb_bits);
+            code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
+        }
+    }
+    BS_FUNC(priv_skip_remaining)(bc, n);
+
+    return code;
+}
+
+#undef BSCTX
+#undef BS_FUNC
+#undef BS_JOIN3
+#undef BS_JOIN
+#undef BS_SUFFIX_UPPER
+#undef BS_SUFFIX_LOWER
diff --git a/tests/ref/fate/source b/tests/ref/fate/source
index 16ea7ef9c1..3b7ea9c379 100644
--- a/tests/ref/fate/source
+++ b/tests/ref/fate/source
@@ -21,6 +21,7 @@ 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: