(((const uint8_t*)(x))[2] << 8) | \
((const uint8_t*)(x))[3])
-# define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
+#define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
-/**
- * Structure for bistream I/O.
- *
- * The buffer, buffer_end and size_in_bits fields must be present and are used
- * by every reader.
- */
+/** Structure for bistream I/O. */
struct getbit_context {
- const uint8_t *buffer, *buffer_end;
+ /* Start of the internal buffer. */
+ const uint8_t *buffer;
+ /* End of the internal buffer. */
+ const uint8_t *buffer_end;
+ /** Bit counter. */
int index;
- int size_in_bits;
};
#define VLC_TYPE int16_t
* Refill the internal cache from the bitstream.
*/
#define UPDATE_CACHE(name, gb)\
- name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer) \
+ name##_cache= AV_RB32( ((gb)->buffer) \
+ (name##_index >> 3) ) << (name##_index & 0x07);\
/**
/**
* Increment the internal bit counter.
*
- * \sa SKIP_CACHE, SKIP_BITS.
+ * \sa SKIP_CACHE.
*/
#define SKIP_COUNTER(name, gb, num)\
name##_index += (num);\
-/**
- * Skip over the next num bits.
- *
- * This is equivalent to SKIP_CACHE; SKIP_COUNTER.
- */
-#define SKIP_BITS(name, gb, num)\
- {\
- SKIP_CACHE(name, gb, num)\
- SKIP_COUNTER(name, gb, num)\
- }\
-
-/** This is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER. */
-#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
-
/** Return the next num bits. */
#define SHOW_UBITS(name, gb, num)\
NEG_USR32(name##_cache, num)
OPEN_READER(re, s)
UPDATE_CACHE(re, s)
tmp = SHOW_UBITS(re, s, n);
- LAST_SKIP_BITS(re, s, n)
+ SKIP_COUNTER(re, s, n)
CLOSE_READER(re, s)
return tmp;
}
-/**
- * Show 1-17 bits.
- */
-static inline unsigned int show_bits(struct getbit_context *s, int n)
-{
- register int tmp;
- OPEN_READER(re, s)
- UPDATE_CACHE(re, s)
- tmp = SHOW_UBITS(re, s, n);
- return tmp;
-}
-
static inline void skip_bits(struct getbit_context *s, int n)
{
/* gcc seems to optimize this to s->index+=n for the ALT_READER :)) */
OPEN_READER(re, s)
UPDATE_CACHE(re, s)
- LAST_SKIP_BITS(re, s, n)
+ SKIP_COUNTER(re, s, n)
CLOSE_READER(re, s)
}
* bytes larger then the actual read bits * because some optimized bitstream
* readers read 32 or 64 bit at once and could read over the end.
*
- * \param bit_size The size of the buffer in bits.
+ * \param bit_size The size of the buffer in bytes.
*/
static inline void init_get_bits(struct getbit_context *s,
- const uint8_t * buffer, int bit_size)
+ const uint8_t *buffer, int size)
{
- int buffer_size = (bit_size + 7) >> 3;
- if (buffer_size < 0 || bit_size < 0) {
- buffer_size = bit_size = 0;
- buffer = NULL;
- }
s->buffer = buffer;
- s->size_in_bits = bit_size;
- s->buffer_end = buffer + buffer_size;
+ s->buffer_end = buffer + size;
s->index = 0;
}
-int init_vlc(struct vlc *vlc, int nb_bits, int nb_codes,
- const void *bits, int bits_wrap, int bits_size,
- const void *codes, int codes_wrap, int codes_size);
+void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
+ const void *codes, int codes_size);
void free_vlc(struct vlc *vlc);
/**
+ * Parse a vlc code.
+ *
+ * \param bits The number of bits which will be read at once, must be
+ * identical to nb_bits in init_vlc()
*
- * if the vlc code is invalid and max_depth=1 than no bits will be removed
- * if the vlc code is invalid and max_depth>1 than the number of bits removed
- * is undefined
+ * \param max_depth The number of times bits bits must be read to completely
+ * read the longest vlc code = (max_vlc_length + bits - 1) / bits.
*/
-#define GET_VLC(code, name, gb, table, bits, max_depth)\
-{\
- int n, index, nb_bits;\
-\
- index= SHOW_UBITS(name, gb, bits);\
- code = table[index][0];\
- n = table[index][1];\
-\
- if(max_depth > 1 && n < 0){\
- LAST_SKIP_BITS(name, gb, bits)\
- UPDATE_CACHE(name, gb)\
-\
- nb_bits = -n;\
-\
- index= SHOW_UBITS(name, gb, nb_bits) + code;\
- code = table[index][0];\
- n = table[index][1];\
- if(max_depth > 2 && n < 0){\
- LAST_SKIP_BITS(name, gb, nb_bits)\
- UPDATE_CACHE(name, gb)\
-\
- nb_bits = -n;\
-\
- index= SHOW_UBITS(name, gb, nb_bits) + code;\
- code = table[index][0];\
- n = table[index][1];\
- }\
- }\
- SKIP_BITS(name, gb, n)\
+static inline int get_vlc(struct getbit_context *gb, VLC_TYPE(*table)[2],
+ int bits, int max_depth)
+{
+ int n, idx, nb_bits, code;
+
+ OPEN_READER(re, gb)
+ UPDATE_CACHE(re, gb)
+ idx = SHOW_UBITS(re, gb, bits);
+ code = table[idx][0];
+ n = table[idx][1];
+ if (max_depth > 1 && n < 0) {
+ SKIP_COUNTER(re, gb, bits)
+ UPDATE_CACHE(re, gb)
+ nb_bits = -n;
+ idx = SHOW_UBITS(re, gb, nb_bits) + code;
+ code = table[idx][0];
+ n = table[idx][1];
+ if (max_depth > 2 && n < 0) {
+ SKIP_COUNTER(re, gb, nb_bits)
+ UPDATE_CACHE(re, gb)
+ nb_bits = -n;
+ idx = SHOW_UBITS(re, gb, nb_bits) + code;
+ code = table[idx][0];
+ n = table[idx][1];
+ }
+ }
+ SKIP_CACHE(re, gb, n)
+ SKIP_COUNTER(re, gb, n)
+ CLOSE_READER(re, gb)
+ return code;
}
projects / paraslash.git / blobdiff