X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fget_bits.h;h=648c958cb02aa6e8038be54b96f3b9b683a6157a;hb=c48883163d6c7ff0806687bf3ee33ca9f8e7dede;hp=3b09dfd2859f36676b5d425950de245488218806;hpb=2f9d6ffda78725e11b351a7a5d69414a32010810;p=ffmpeg diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h index 3b09dfd2859..648c958cb02 100644 --- a/libavcodec/get_bits.h +++ b/libavcodec/get_bits.h @@ -27,40 +27,33 @@ #define AVCODEC_GET_BITS_H #include -#include -#include -#include "libavutil/bswap.h" #include "libavutil/common.h" #include "libavutil/intreadwrite.h" #include "libavutil/log.h" #include "mathops.h" -#if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER) -# define ALT_BITSTREAM_READER -#endif - -#if !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER) -# if ARCH_ARM && !HAVE_FAST_UNALIGNED -# define A32_BITSTREAM_READER -# else -# define ALT_BITSTREAM_READER -//#define A32_BITSTREAM_READER -# endif +/* + * Safe bitstream reading: + * optionally, the get_bits API can check to ensure that we + * don't read past input buffer boundaries. This is protected + * with CONFIG_SAFE_BITSTREAM_READER at the global level, and + * then below that with UNCHECKED_BITSTREAM_READER at the per- + * decoder level. This means that decoders that check internally + * can "#define UNCHECKED_BITSTREAM_READER 1" to disable + * overread checks. + * Boundary checking causes a minor performance penalty so for + * applications that won't want/need this, it can be disabled + * globally using "#define CONFIG_SAFE_BITSTREAM_READER 0". + */ +#ifndef UNCHECKED_BITSTREAM_READER +#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER #endif -/* bit input */ -/* buffer, buffer_end and size_in_bits must be present and used by every reader */ typedef struct GetBitContext { const uint8_t *buffer, *buffer_end; -#ifdef ALT_BITSTREAM_READER int index; -#elif defined A32_BITSTREAM_READER - uint32_t *buffer_ptr; - uint32_t cache0; - uint32_t cache1; - int bit_count; -#endif int size_in_bits; + int size_in_bits_plus8; } GetBitContext; #define VLC_TYPE int16_t @@ -85,13 +78,13 @@ gb getbitcontext OPEN_READER(name, gb) - loads gb into local variables + load gb into local variables CLOSE_READER(name, gb) - stores local vars in gb + store local vars in gb UPDATE_CACHE(name, gb) - refills the internal cache from the bitstream + refill the internal cache from the bitstream after this call at least MIN_CACHE_BITS will be available, GET_CACHE(name, gb) @@ -113,148 +106,94 @@ SKIP_CACHE(name, gb, num) SKIP_COUNTER(name, gb, num) will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS) -LAST_SKIP_CACHE(name, gb, num) - will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing - LAST_SKIP_BITS(name, gb, num) - is equivalent to LAST_SKIP_CACHE; SKIP_COUNTER + like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER for examples see get_bits, show_bits, skip_bits, get_vlc */ -#ifdef ALT_BITSTREAM_READER +#ifdef LONG_BITSTREAM_READER +# define MIN_CACHE_BITS 32 +#else # define MIN_CACHE_BITS 25 +#endif -# define OPEN_READER(name, gb) \ +#define OPEN_READER(name, gb) \ unsigned int name##_index = (gb)->index; \ av_unused unsigned int name##_cache -# define CLOSE_READER(name, gb) (gb)->index = name##_index +#define CLOSE_READER(name, gb) (gb)->index = name##_index -# ifdef ALT_BITSTREAM_READER_LE -# define UPDATE_CACHE(name, gb) \ - name##_cache = AV_RL32(((const uint8_t *)(gb)->buffer)+(name##_index>>3)) >> (name##_index&0x07) +#ifdef BITSTREAM_READER_LE -# define SKIP_CACHE(name, gb, num) name##_cache >>= (num) +# ifdef LONG_BITSTREAM_READER +# define UPDATE_CACHE(name, gb) name##_cache = \ + AV_RL64((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7) # else -# define UPDATE_CACHE(name, gb) \ - name##_cache = AV_RB32(((const uint8_t *)(gb)->buffer)+(name##_index>>3)) << (name##_index&0x07) +# define UPDATE_CACHE(name, gb) name##_cache = \ + AV_RL32((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7) +# endif -# define SKIP_CACHE(name, gb, num) name##_cache <<= (num) +# define SKIP_CACHE(name, gb, num) name##_cache >>= (num) + +#else + +# ifdef LONG_BITSTREAM_READER +# define UPDATE_CACHE(name, gb) name##_cache = \ + AV_RB64((gb)->buffer + (name##_index >> 3)) >> (32 - (name##_index & 7)) +# else +# define UPDATE_CACHE(name, gb) name##_cache = \ + AV_RB32((gb)->buffer + (name##_index >> 3)) << (name##_index & 7) # endif -// FIXME name? +# define SKIP_CACHE(name, gb, num) name##_cache <<= (num) + +#endif + +#if UNCHECKED_BITSTREAM_READER # define SKIP_COUNTER(name, gb, num) name##_index += (num) +#else +# define SKIP_COUNTER(name, gb, num) \ + name##_index = FFMIN((gb)->size_in_bits_plus8, name##_index + (num)) +#endif -# define SKIP_BITS(name, gb, num) do { \ +#define SKIP_BITS(name, gb, num) do { \ SKIP_CACHE(name, gb, num); \ SKIP_COUNTER(name, gb, num); \ } while (0) -# define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) -# define LAST_SKIP_CACHE(name, gb, num) +#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) -# ifdef ALT_BITSTREAM_READER_LE +#ifdef BITSTREAM_READER_LE # define SHOW_UBITS(name, gb, num) zero_extend(name##_cache, num) - # define SHOW_SBITS(name, gb, num) sign_extend(name##_cache, num) -# else +#else # define SHOW_UBITS(name, gb, num) NEG_USR32(name##_cache, num) - # define SHOW_SBITS(name, gb, num) NEG_SSR32(name##_cache, num) -# endif +#endif -# define GET_CACHE(name, gb) ((uint32_t)name##_cache) +#define GET_CACHE(name, gb) ((uint32_t)name##_cache) -static inline int get_bits_count(const GetBitContext *s){ +static inline int get_bits_count(const GetBitContext *s) +{ return s->index; } static inline void skip_bits_long(GetBitContext *s, int n){ +#if UNCHECKED_BITSTREAM_READER s->index += n; -} - -#elif defined A32_BITSTREAM_READER - -# define MIN_CACHE_BITS 32 - -# define OPEN_READER(name, gb) \ - int name##_bit_count = (gb)->bit_count; \ - uint32_t name##_cache0 = (gb)->cache0; \ - uint32_t name##_cache1 = (gb)->cache1; \ - uint32_t *name##_buffer_ptr = (gb)->buffer_ptr - -# define CLOSE_READER(name, gb) do { \ - (gb)->bit_count = name##_bit_count; \ - (gb)->cache0 = name##_cache0; \ - (gb)->cache1 = name##_cache1; \ - (gb)->buffer_ptr = name##_buffer_ptr; \ - } while (0) - -# define UPDATE_CACHE(name, gb) do { \ - if(name##_bit_count > 0){ \ - const uint32_t next = av_be2ne32(*name##_buffer_ptr); \ - name##_cache0 |= NEG_USR32(next, name##_bit_count); \ - name##_cache1 |= next << name##_bit_count; \ - name##_buffer_ptr++; \ - name##_bit_count -= 32; \ - } \ - } while (0) - -#if ARCH_X86 -# define SKIP_CACHE(name, gb, num) \ - __asm__("shldl %2, %1, %0 \n\t" \ - "shll %2, %1 \n\t" \ - : "+r" (name##_cache0), "+r" (name##_cache1) \ - : "Ic" ((uint8_t)(num))) #else -# define SKIP_CACHE(name, gb, num) do { \ - name##_cache0 <<= (num); \ - name##_cache0 |= NEG_USR32(name##_cache1,num); \ - name##_cache1 <<= (num); \ - } while (0) + s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); #endif - -# define SKIP_COUNTER(name, gb, num) name##_bit_count += (num) - -# define SKIP_BITS(name, gb, num) do { \ - SKIP_CACHE(name, gb, num); \ - SKIP_COUNTER(name, gb, num); \ - } while (0) - -# define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num) -# define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num) - -# define SHOW_UBITS(name, gb, num) NEG_USR32(name##_cache0, num) - -# define SHOW_SBITS(name, gb, num) NEG_SSR32(name##_cache0, num) - -# define GET_CACHE(name, gb) name##_cache0 - -static inline int get_bits_count(const GetBitContext *s) { - return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count; -} - -static inline void skip_bits_long(GetBitContext *s, int n){ - OPEN_READER(re, s); - re_bit_count += n; - re_buffer_ptr += re_bit_count>>5; - re_bit_count &= 31; - re_cache0 = av_be2ne32(re_buffer_ptr[-1]) << re_bit_count; - re_cache1 = 0; - UPDATE_CACHE(re, s); - CLOSE_READER(re, s); } -#endif - /** * read mpeg1 dc style vlc (sign bit + mantisse with no MSB). * if MSB not set it is negative * @param n length in bits - * @author BERO */ -static inline int get_xbits(GetBitContext *s, int n){ +static inline int get_xbits(GetBitContext *s, int n) +{ register int sign; register int32_t cache; OPEN_READER(re, s); @@ -266,7 +205,8 @@ static inline int get_xbits(GetBitContext *s, int n){ return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; } -static inline int get_sbits(GetBitContext *s, int n){ +static inline int get_sbits(GetBitContext *s, int n) +{ register int tmp; OPEN_READER(re, s); UPDATE_CACHE(re, s); @@ -279,7 +219,8 @@ static inline int get_sbits(GetBitContext *s, int n){ /** * Read 1-25 bits. */ -static inline unsigned int get_bits(GetBitContext *s, int n){ +static inline unsigned int get_bits(GetBitContext *s, int n) +{ register int tmp; OPEN_READER(re, s); UPDATE_CACHE(re, s); @@ -290,9 +231,10 @@ static inline unsigned int get_bits(GetBitContext *s, int n){ } /** - * Shows 1-25 bits. + * Show 1-25 bits. */ -static inline unsigned int show_bits(GetBitContext *s, int n){ +static inline unsigned int show_bits(GetBitContext *s, int n) +{ register int tmp; OPEN_READER(re, s); UPDATE_CACHE(re, s); @@ -300,49 +242,53 @@ static inline unsigned int show_bits(GetBitContext *s, int n){ return tmp; } -static inline void skip_bits(GetBitContext *s, int n){ - //Note gcc seems to optimize this to s->index+=n for the ALT_READER :)) +static inline void skip_bits(GetBitContext *s, int n) +{ OPEN_READER(re, s); UPDATE_CACHE(re, s); LAST_SKIP_BITS(re, s, n); CLOSE_READER(re, s); } -static inline unsigned int get_bits1(GetBitContext *s){ -#ifdef ALT_BITSTREAM_READER +static inline unsigned int get_bits1(GetBitContext *s) +{ unsigned int index = s->index; uint8_t result = s->buffer[index>>3]; -#ifdef ALT_BITSTREAM_READER_LE +#ifdef BITSTREAM_READER_LE result >>= index & 7; result &= 1; #else result <<= index & 7; result >>= 8 - 1; #endif - index++; +#if !UNCHECKED_BITSTREAM_READER + if (s->index < s->size_in_bits_plus8) +#endif + index++; s->index = index; return result; -#else - return get_bits(s, 1); -#endif } -static inline unsigned int show_bits1(GetBitContext *s){ +static inline unsigned int show_bits1(GetBitContext *s) +{ return show_bits(s, 1); } -static inline void skip_bits1(GetBitContext *s){ +static inline void skip_bits1(GetBitContext *s) +{ skip_bits(s, 1); } /** - * reads 0-32 bits. + * Read 0-32 bits. */ -static inline unsigned int get_bits_long(GetBitContext *s, int n){ - if (n <= MIN_CACHE_BITS) return get_bits(s, n); +static inline unsigned int get_bits_long(GetBitContext *s, int n) +{ + if (n <= MIN_CACHE_BITS) + return get_bits(s, n); else { -#ifdef ALT_BITSTREAM_READER_LE +#ifdef BITSTREAM_READER_LE int ret = get_bits(s, 16); return ret | (get_bits(s, n-16) << 16); #else @@ -353,17 +299,20 @@ static inline unsigned int get_bits_long(GetBitContext *s, int n){ } /** - * reads 0-32 bits as a signed integer. + * Read 0-32 bits as a signed integer. */ -static inline int get_sbits_long(GetBitContext *s, int n) { +static inline int get_sbits_long(GetBitContext *s, int n) +{ return sign_extend(get_bits_long(s, n), n); } /** - * shows 0-32 bits. + * Show 0-32 bits. */ -static inline unsigned int show_bits_long(GetBitContext *s, int n){ - if (n <= MIN_CACHE_BITS) return show_bits(s, n); +static inline unsigned int show_bits_long(GetBitContext *s, int n) +{ + if (n <= MIN_CACHE_BITS) + return show_bits(s, n); else { GetBitContext gb = *s; return get_bits_long(&gb, n); @@ -380,16 +329,13 @@ static inline int check_marker(GetBitContext *s, const char *msg) } /** - * init GetBitContext. + * Inititalize GetBitContext. * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger than 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 - * - * While GetBitContext stores the buffer size, for performance reasons you are - * responsible for checking for the buffer end yourself (take advantage of the padding)! */ -static inline void init_get_bits(GetBitContext *s, - const uint8_t *buffer, int bit_size) +static inline void init_get_bits(GetBitContext *s, const uint8_t *buffer, + int bit_size) { int buffer_size = (bit_size+7)>>3; if (buffer_size < 0 || bit_size < 0) { @@ -399,14 +345,9 @@ static inline void init_get_bits(GetBitContext *s, s->buffer = buffer; s->size_in_bits = bit_size; + s->size_in_bits_plus8 = bit_size + 8; s->buffer_end = buffer + buffer_size; -#ifdef ALT_BITSTREAM_READER s->index = 0; -#elif defined A32_BITSTREAM_READER - s->buffer_ptr = (uint32_t*)((intptr_t)buffer & ~3); - s->bit_count = 32 + 8*((intptr_t)buffer & 3); - skip_bits_long(s, 0); -#endif } static inline void align_get_bits(GetBitContext *s) @@ -442,12 +383,12 @@ void free_vlc(VLC *vlc); /** - * * 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. */ -#define GET_VLC(code, name, gb, table, bits, max_depth) do { \ +#define GET_VLC(code, name, gb, table, bits, max_depth) \ + do { \ int n, nb_bits; \ unsigned int index; \ \ @@ -478,7 +419,8 @@ void free_vlc(VLC *vlc); SKIP_BITS(name, gb, n); \ } while (0) -#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update) do { \ +#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update) \ + do { \ int n, nb_bits; \ unsigned int index; \ \ @@ -504,7 +446,7 @@ void free_vlc(VLC *vlc); /** - * parses a vlc code, faster than get_vlc() + * 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 @@ -512,7 +454,7 @@ void free_vlc(VLC *vlc); * = (max_vlc_length + bits - 1) / bits */ static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], - int bits, int max_depth) + int bits, int max_depth) { int code; @@ -525,7 +467,8 @@ static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], return code; } -static inline int decode012(GetBitContext *gb){ +static inline int decode012(GetBitContext *gb) +{ int n; n = get_bits1(gb); if (n == 0) @@ -534,7 +477,8 @@ static inline int decode012(GetBitContext *gb){ return get_bits1(gb) + 1; } -static inline int decode210(GetBitContext *gb){ +static inline int decode210(GetBitContext *gb) +{ if (get_bits1(gb)) return 0; else @@ -549,7 +493,8 @@ static inline int get_bits_left(GetBitContext *gb) //#define TRACE #ifdef TRACE -static inline void print_bin(int bits, int n){ +static inline void print_bin(int bits, int n) +{ int i; for (i = n-1; i >= 0; i--) { @@ -560,7 +505,8 @@ static inline void print_bin(int bits, int n){ } static inline int get_bits_trace(GetBitContext *s, int n, char *file, - const char *func, int line){ + const char *func, int line) +{ int r = get_bits(s, n); print_bin(r, n); @@ -570,7 +516,8 @@ static inline int get_bits_trace(GetBitContext *s, int n, char *file, } static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, - const char *func, int line){ + const char *func, int line) +{ int show = show_bits(s, 24); int pos = get_bits_count(s); int r = get_vlc2(s, table, bits, max_depth); @@ -584,7 +531,8 @@ static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], return r; } static inline int get_xbits_trace(GetBitContext *s, int n, char *file, - const char *func, int line){ + const char *func, int line) +{ int show = show_bits(s, n); int r = get_xbits(s, n);