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avcodec/vlc: Use structure instead of VLC_TYPE array as VLC element

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In C, qualifiers for arrays are broken:
const VLC_TYPE (*foo)[2] is a pointer to an array of two const VLC_TYPE
elements and unfortunately this is not compatible with a pointer
to a const array of two VLC_TYPE, because the latter does not exist
as array types are never qualified (the qualifier applies to the base
type instead). This is the reason why get_vlc2() doesn't accept
a const VLC table despite not modifying the table at all, as
there is no automatic conversion from VLC_TYPE (*)[2] to
const VLC_TYPE (*)[2].

Fix this by using a structure VLCElem for the VLC table.
This also has the advantage of making it clear which
element is which.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-06-13 23:02:57 +02:00
parent 97141ffeec
commit 2d764069be
43 changed files with 120 additions and 116 deletions
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24
libavcodec/get_bits.h
View file

@ -710,8 +710,8 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
unsigned int index; \
\
index = SHOW_UBITS(name, gb, bits); \
code = table[index][0]; \
n = table[index][1]; \
code = table[index].sym; \
n = table[index].len; \
\
if (max_depth > 1 && n < 0) { \
LAST_SKIP_BITS(name, gb, bits); \
@ -720,8 +720,8 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
nb_bits = -n; \
\
index = SHOW_UBITS(name, gb, nb_bits) + code; \
code = table[index][0]; \
n = table[index][1]; \
code = table[index].sym; \
n = table[index].len; \
if (max_depth > 2 && n < 0) { \
LAST_SKIP_BITS(name, gb, nb_bits); \
UPDATE_CACHE(name, gb); \
@ -729,8 +729,8 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
nb_bits = -n; \
\
index = SHOW_UBITS(name, gb, nb_bits) + code; \
code = table[index][0]; \
n = table[index][1]; \
code = table[index].sym; \
n = table[index].len; \
} \
} \
SKIP_BITS(name, gb, n); \
@ -775,15 +775,15 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
/* Return the LUT element for the given bitstream configuration. */
static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits,
VLC_TYPE (*table)[2])
const VLCElem *table)
{
unsigned idx;
*nb_bits = -*n;
idx = show_bits(s, *nb_bits) + code;
*n = table[idx][1];
*n = table[idx].len;
return table[idx][0];
return table[idx].sym;
}
/**
@ -795,14 +795,14 @@ static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits,
* = (max_vlc_length + bits - 1) / bits
* @returns the code parsed or -1 if no vlc matches
*/
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
static av_always_inline int get_vlc2(GetBitContext *s, const VLCElem *table,
int bits, int max_depth)
{
#if CACHED_BITSTREAM_READER
int nb_bits;
unsigned idx = show_bits(s, bits);
int code = table[idx][0];
int n = table[idx][1];
int code = table[idx].sym;
int n = table[idx].len;
if (max_depth > 1 && n < 0) {
skip_remaining(s, bits);