X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=bitstream.h;h=5890d08c89d4033f7fefb9a19be525860a701d77;hp=88b62f94032a242ee16fd17400dacf63f75fdb39;hb=741c19c2a25c5d9e165cb99f7ff512209b7bade6;hpb=232020d1a15641c8a492c07f79f59df7d4d279ea diff --git a/bitstream.h b/bitstream.h index 88b62f94..5890d08c 100644 --- a/bitstream.h +++ b/bitstream.h @@ -11,9 +11,9 @@ /** Structure for bistream I/O. */ struct getbit_context { - /* Start of the internal buffer. */ + /** Start of the internal buffer. */ const uint8_t *buffer; - /* End of the internal buffer. */ + /** End of the internal buffer. */ const uint8_t *buffer_end; /** Bit counter. */ int index; @@ -21,10 +21,16 @@ struct getbit_context { #define VLC_TYPE int16_t +/** A variable length code table. */ struct vlc { + /** Number of bits of the table. */ int bits; - VLC_TYPE(*table)[2]; ///< code, bits - int table_size, table_allocated; + /** The code and the bits table. */ + VLC_TYPE(*table)[2]; + /** The size of the table. */ + int table_size; + /** Amount of memory allocated so far. */ + int table_allocated; }; static inline uint32_t show_bits(struct getbit_context *gbc, int num) @@ -63,11 +69,13 @@ static inline unsigned int get_bit(struct getbit_context *gbc) /** * Initialize a getbit_context structure. * - * \param buffer The bitstream buffer. It must be FF_INPUT_BUFFER_PADDING_SIZE - * 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 gbc The structure to initialize. + * \param buffer The bitstream buffer. + * \param size The size of the buffer in bytes. * - * \param bit_size The size of the buffer in bytes. + * The bitstream buffer must be 4 bytes larger then the actual read bits + * because the bitstream reader might read 32 bits at once and could read over + * the end. */ static inline void init_get_bits(struct getbit_context *gbc, const uint8_t *buffer, int size) @@ -79,40 +87,6 @@ static inline void init_get_bits(struct getbit_context *gbc, 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() - * - * \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. - */ -static inline int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2], - int bits, int max_depth) -{ - int n, idx, nb_bits, code; - - idx = show_bits(gbc, bits); - code = table[idx][0]; - n = table[idx][1]; - if (max_depth > 1 && n < 0) { - skip_bits(gbc, bits); - nb_bits = -n; - idx = show_bits(gbc, nb_bits) + code; - code = table[idx][0]; - n = table[idx][1]; - if (max_depth > 2 && n < 0) { - skip_bits(gbc, nb_bits); - nb_bits = -n; - idx = show_bits(gbc, nb_bits) + code; - code = table[idx][0]; - n = table[idx][1]; - } - } - skip_bits(gbc, n); - return code; -} +int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2], int bits, + int max_depth);