diff --git a/libavcodec/vlc.c b/libavcodec/vlc.c index 7786043086..aa84ca6b3c 100644 --- a/libavcodec/vlc.c +++ b/libavcodec/vlc.c @@ -350,6 +350,74 @@ fail: return AVERROR_INVALIDDATA; } +av_cold void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size, + int nb_bits, int nb_codes, + const int8_t *lens, int lens_wrap, + const void *symbols, int symbols_wrap, int symbols_size, + int offset, int flags) +{ + VLC vlc = { .table = table, .table_allocated = table_size }; + + ff_vlc_init_from_lengths(&vlc, nb_bits, nb_codes, lens, lens_wrap, + symbols, symbols_wrap, symbols_size, + offset, flags | VLC_INIT_USE_STATIC, NULL); +} + +av_cold const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state, + int nb_bits, int nb_codes, + const int8_t *lens, int lens_wrap, + const void *symbols, int symbols_wrap, int symbols_size, + int offset, int flags) +{ + VLC vlc = { .table = state->table, .table_allocated = state->size }; + + ff_vlc_init_from_lengths(&vlc, nb_bits, nb_codes, lens, lens_wrap, + symbols, symbols_wrap, symbols_size, + offset, flags | VLC_INIT_STATIC_OVERLONG, NULL); + + state->table += vlc.table_size; + state->size -= vlc.table_size; + + return vlc.table; +} + +av_cold void ff_vlc_init_table_sparse(VLCElem table[], int table_size, + int nb_bits, int nb_codes, + const void *bits, int bits_wrap, int bits_size, + const void *codes, int codes_wrap, int codes_size, + const void *symbols, int symbols_wrap, int symbols_size, + int flags) +{ + VLC vlc = { .table = table, .table_allocated = table_size }; + + ff_vlc_init_sparse(&vlc, nb_bits, nb_codes, + bits, bits_wrap, bits_size, + codes, codes_wrap, codes_size, + symbols, symbols_wrap, symbols_size, + flags | VLC_INIT_USE_STATIC); +} + +av_cold const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state, + int nb_bits, int nb_codes, + const void *bits, int bits_wrap, int bits_size, + const void *codes, int codes_wrap, int codes_size, + const void *symbols, int symbols_wrap, int symbols_size, + int flags) +{ + VLC vlc = { .table = state->table, .table_allocated = state->size }; + + ff_vlc_init_sparse(&vlc, nb_bits, nb_codes, + bits, bits_wrap, bits_size, + codes, codes_wrap, codes_size, + symbols, symbols_wrap, symbols_size, + flags | VLC_INIT_STATIC_OVERLONG); + + state->table += vlc.table_size; + state->size -= vlc.table_size; + + return vlc.table; +} + static void add_level(VLC_MULTI_ELEM *table, const int is16bit, const int num, const int numbits, const VLCcode *buf, diff --git a/libavcodec/vlc.h b/libavcodec/vlc.h index 3f7c033a78..679666801a 100644 --- a/libavcodec/vlc.h +++ b/libavcodec/vlc.h @@ -19,8 +19,11 @@ #ifndef AVCODEC_VLC_H #define AVCODEC_VLC_H +#include #include +#include "libavutil/macros.h" + #define VLC_MULTI_MAX_SYMBOLS 6 // When changing this, be sure to also update tableprint_vlc.h accordingly. @@ -223,4 +226,103 @@ void ff_vlc_free(VLC *vlc); NULL); \ } while (0) +/** + * For static VLCs, the number of bits can often be hardcoded + * at each get_vlc2() callsite. Then using a full VLC would be uneconomical, + * because only VLC.table would ever be accessed after initialization. + * The following functions provide wrappers around the relevant ff_vlc_init_* + * functions suitable for said task. + * + * The ff_vlc_init_tables_* functions are intended to be used for initializing + * a series of VLCs. The user initializes a VLCInitState with the details + * about the underlying array of VLCElem; it is automatically updated by + * the ff_vlc_init_tables_* functions (i.e. table is incremented and size + * decremented by the number of elements of the current table). + * The VLC_INIT_STATIC_OVERLONG flag is also automatically added. + * These functions return a pointer to the table just initialized, + * potentially to be used in arrays of pointer to VLC tables. + * + * The ff_vlc_init_table_* functions are intended to be used for initializing + * a single VLC table, given by table and table_size. The VLC_INIT_USE_STATIC + * flag is automatically added. + */ + +typedef struct VLCInitState { + VLCElem *table; ///< points to where the next VLC table will be placed + unsigned size; ///< remaining number of elements in table +} VLCInitState; + +#define VLC_INIT_STATE(_table) { .table = (_table), .size = FF_ARRAY_ELEMS(_table) } + +void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size, + int nb_bits, int nb_codes, + const int8_t *lens, int lens_wrap, + const void *symbols, int symbols_wrap, int symbols_size, + int offset, int flags); + +const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state, + int nb_bits, int nb_codes, + const int8_t *lens, int lens_wrap, + const void *symbols, int symbols_wrap, int symbols_size, + int offset, int flags); + +void ff_vlc_init_table_sparse(VLCElem table[], int table_size, + int nb_bits, int nb_codes, + const void *bits, int bits_wrap, int bits_size, + const void *codes, int codes_wrap, int codes_size, + const void *symbols, int symbols_wrap, int symbols_size, + int flags); + +const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state, + int nb_bits, int nb_codes, + const void *bits, int bits_wrap, int bits_size, + const void *codes, int codes_wrap, int codes_size, + const void *symbols, int symbols_wrap, int symbols_size, + int flags); + +static inline +const VLCElem *ff_vlc_init_tables(VLCInitState *state, + int nb_bits, int nb_codes, + const void *bits, int bits_wrap, int bits_size, + const void *codes, int codes_wrap, int codes_size, + int flags) +{ + return ff_vlc_init_tables_sparse(state, nb_bits, nb_codes, + bits, bits_wrap, bits_size, + codes, codes_wrap, codes_size, + NULL, 0, 0, flags); +} + +#define VLC_INIT_STATIC_SPARSE_TABLE(vlc_table, nb_bits, nb_codes, \ + bits, bits_wrap, bits_size, \ + codes, codes_wrap, codes_size, \ + symbols, symbols_wrap, symbols_size, \ + flags) \ + ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \ + (nb_bits), (nb_codes), \ + (bits), (bits_wrap), (bits_size), \ + (codes), (codes_wrap), (codes_size), \ + (symbols), (symbols_wrap), (symbols_size), \ + (flags)) + +#define VLC_INIT_STATIC_TABLE(vlc_table, nb_bits, nb_codes, \ + bits, bits_wrap, bits_size, \ + codes, codes_wrap, codes_size, \ + flags) \ + ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \ + (nb_bits), (nb_codes), \ + (bits), (bits_wrap), (bits_size), \ + (codes), (codes_wrap), (codes_size), \ + NULL, 0, 0, (flags)) + +#define VLC_INIT_STATIC_TABLE_FROM_LENGTHS(vlc_table, nb_bits, nb_codes, \ + lens, lens_wrap, \ + syms, syms_wrap, syms_size, \ + offset, flags) \ + ff_vlc_init_table_from_lengths(vlc_table, FF_ARRAY_ELEMS(vlc_table), \ + (nb_bits), (nb_codes), \ + (lens), (lens_wrap), \ + (syms), (syms_wrap), (syms_size), \ + (offset), (flags)) + #endif /* AVCODEC_VLC_H */