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@ -27,20 +27,33 @@ |
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#define AVCODEC_GET_BITS_H |
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#include <stdint.h> |
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#include <stdlib.h> |
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#include <assert.h> |
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#include "libavutil/bswap.h" |
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#include "libavutil/common.h" |
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#include "libavutil/intreadwrite.h" |
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#include "libavutil/log.h" |
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#include "mathops.h" |
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/* bit input */ |
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/* buffer, buffer_end and size_in_bits must be present and used by every reader */ |
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/*
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* Safe bitstream reading: |
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* optionally, the get_bits API can check to ensure that we |
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* don't read past input buffer boundaries. This is protected |
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* with CONFIG_SAFE_BITSTREAM_READER at the global level, and |
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* then below that with UNCHECKED_BITSTREAM_READER at the per- |
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* decoder level. This means that decoders that check internally |
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* can "#define UNCHECKED_BITSTREAM_READER 1" to disable |
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* overread checks. |
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* Boundary checking causes a minor performance penalty so for |
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* applications that won't want/need this, it can be disabled |
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* globally using "#define CONFIG_SAFE_BITSTREAM_READER 0". |
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*/ |
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#ifndef UNCHECKED_BITSTREAM_READER |
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#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER |
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#endif |
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typedef struct GetBitContext { |
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const uint8_t *buffer, *buffer_end; |
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int index; |
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int size_in_bits; |
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int size_in_bits_plus8; |
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} GetBitContext; |
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#define VLC_TYPE int16_t |
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@ -93,11 +106,8 @@ SKIP_CACHE(name, gb, num) |
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SKIP_COUNTER(name, gb, num) |
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will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS) |
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LAST_SKIP_CACHE(name, gb, num) |
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will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing |
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LAST_SKIP_BITS(name, gb, num) |
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is equivalent to LAST_SKIP_CACHE; SKIP_COUNTER |
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like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER |
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for examples see get_bits, show_bits, skip_bits, get_vlc |
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*/ |
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@ -115,29 +125,37 @@ for examples see get_bits, show_bits, skip_bits, get_vlc |
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#define CLOSE_READER(name, gb) (gb)->index = name##_index |
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#ifdef ALT_BITSTREAM_READER_LE |
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# ifdef LONG_BITSTREAM_READER |
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# define UPDATE_CACHE(name, gb) \ |
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name##_cache = AV_RL64((gb)->buffer+(name##_index>>3)) >> (name##_index&0x07) |
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# define UPDATE_CACHE(name, gb) name##_cache = \ |
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AV_RL64((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7) |
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# else |
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# define UPDATE_CACHE(name, gb) \ |
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name##_cache = AV_RL32((gb)->buffer+(name##_index>>3)) >> (name##_index&0x07) |
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# define UPDATE_CACHE(name, gb) name##_cache = \ |
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AV_RL32((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7) |
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# endif |
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# define SKIP_CACHE(name, gb, num) name##_cache >>= (num) |
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#else |
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# ifdef LONG_BITSTREAM_READER |
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# define UPDATE_CACHE(name, gb) \ |
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name##_cache = AV_RB64((gb)->buffer+(name##_index >> 3)) >> (32 - (name##_index & 0x07)) |
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# define UPDATE_CACHE(name, gb) name##_cache = \ |
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AV_RB64((gb)->buffer + (name##_index >> 3)) >> (32 - (name##_index & 7)) |
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# else |
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# define UPDATE_CACHE(name, gb) \ |
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name##_cache = AV_RB32((gb)->buffer+(name##_index>>3)) << (name##_index&0x07) |
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# define UPDATE_CACHE(name, gb) name##_cache = \ |
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AV_RB32((gb)->buffer + (name##_index >> 3)) << (name##_index & 7) |
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# endif |
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# define SKIP_CACHE(name, gb, num) name##_cache <<= (num) |
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#endif |
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// FIXME name?
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#if UNCHECKED_BITSTREAM_READER |
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# define SKIP_COUNTER(name, gb, num) name##_index += (num) |
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#else |
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# define SKIP_COUNTER(name, gb, num) \ |
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name##_index = FFMIN((gb)->size_in_bits_plus8, name##_index + (num)) |
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#endif |
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#define SKIP_BITS(name, gb, num) do { \ |
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SKIP_CACHE(name, gb, num); \
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@ -145,35 +163,37 @@ for examples see get_bits, show_bits, skip_bits, get_vlc |
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} while (0) |
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#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) |
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# define LAST_SKIP_CACHE(name, gb, num) |
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#ifdef ALT_BITSTREAM_READER_LE |
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# define SHOW_UBITS(name, gb, num) zero_extend(name##_cache, num) |
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# define SHOW_SBITS(name, gb, num) sign_extend(name##_cache, num) |
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#else |
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# define SHOW_UBITS(name, gb, num) NEG_USR32(name##_cache, num) |
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# define SHOW_SBITS(name, gb, num) NEG_SSR32(name##_cache, num) |
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#endif |
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#define GET_CACHE(name, gb) ((uint32_t)name##_cache) |
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static inline int get_bits_count(const GetBitContext *s){ |
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static inline int get_bits_count(const GetBitContext *s) |
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{ |
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return s->index; |
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} |
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static inline void skip_bits_long(GetBitContext *s, int n){ |
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#if UNCHECKED_BITSTREAM_READER |
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s->index += n; |
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#else |
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s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); |
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#endif |
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} |
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/**
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* read mpeg1 dc style vlc (sign bit + mantisse with no MSB). |
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* if MSB not set it is negative |
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* @param n length in bits |
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* @author BERO |
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*/ |
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static inline int get_xbits(GetBitContext *s, int n){ |
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static inline int get_xbits(GetBitContext *s, int n) |
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{ |
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register int sign; |
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register int32_t cache; |
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OPEN_READER(re, s); |
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@ -185,7 +205,8 @@ static inline int get_xbits(GetBitContext *s, int n){ |
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return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; |
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} |
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static inline int get_sbits(GetBitContext *s, int n){ |
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static inline int get_sbits(GetBitContext *s, int n) |
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{ |
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register int tmp; |
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OPEN_READER(re, s); |
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UPDATE_CACHE(re, s); |
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@ -198,7 +219,8 @@ static inline int get_sbits(GetBitContext *s, int n){ |
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/**
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* Read 1-25 bits. |
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*/ |
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static inline unsigned int get_bits(GetBitContext *s, int n){ |
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static inline unsigned int get_bits(GetBitContext *s, int n) |
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{ |
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register int tmp; |
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OPEN_READER(re, s); |
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UPDATE_CACHE(re, s); |
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@ -211,7 +233,8 @@ static inline unsigned int get_bits(GetBitContext *s, int n){ |
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/**
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* Show 1-25 bits. |
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*/ |
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static inline unsigned int show_bits(GetBitContext *s, int n){ |
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static inline unsigned int show_bits(GetBitContext *s, int n) |
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{ |
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register int tmp; |
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OPEN_READER(re, s); |
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UPDATE_CACHE(re, s); |
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@ -219,15 +242,16 @@ static inline unsigned int show_bits(GetBitContext *s, int n){ |
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return tmp; |
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} |
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static inline void skip_bits(GetBitContext *s, int n){ |
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//Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
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static inline void skip_bits(GetBitContext *s, int n) |
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{ |
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OPEN_READER(re, s); |
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UPDATE_CACHE(re, s); |
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LAST_SKIP_BITS(re, s, n); |
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CLOSE_READER(re, s); |
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} |
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static inline unsigned int get_bits1(GetBitContext *s){ |
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static inline unsigned int get_bits1(GetBitContext *s) |
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{ |
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unsigned int index = s->index; |
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uint8_t result = s->buffer[index>>3]; |
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#ifdef ALT_BITSTREAM_READER_LE |
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@ -236,6 +260,9 @@ static inline unsigned int get_bits1(GetBitContext *s){ |
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#else |
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result <<= index & 7; |
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result >>= 8 - 1; |
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#endif |
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#if !UNCHECKED_BITSTREAM_READER |
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if (s->index < s->size_in_bits_plus8) |
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#endif |
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index++; |
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s->index = index; |
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@ -243,19 +270,23 @@ static inline unsigned int get_bits1(GetBitContext *s){ |
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return result; |
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} |
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static inline unsigned int show_bits1(GetBitContext *s){ |
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static inline unsigned int show_bits1(GetBitContext *s) |
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{ |
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return show_bits(s, 1); |
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} |
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static inline void skip_bits1(GetBitContext *s){ |
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static inline void skip_bits1(GetBitContext *s) |
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{ |
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skip_bits(s, 1); |
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} |
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/**
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* Read 0-32 bits. |
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*/ |
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static inline unsigned int get_bits_long(GetBitContext *s, int n){ |
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if (n <= MIN_CACHE_BITS) return get_bits(s, n); |
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static inline unsigned int get_bits_long(GetBitContext *s, int n) |
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{ |
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if (n <= MIN_CACHE_BITS) |
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return get_bits(s, n); |
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else { |
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#ifdef ALT_BITSTREAM_READER_LE |
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int ret = get_bits(s, 16); |
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@ -270,15 +301,18 @@ static inline unsigned int get_bits_long(GetBitContext *s, int n){ |
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/**
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* Read 0-32 bits as a signed integer. |
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*/ |
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static inline int get_sbits_long(GetBitContext *s, int n) { |
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static inline int get_sbits_long(GetBitContext *s, int n) |
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{ |
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return sign_extend(get_bits_long(s, n), n); |
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} |
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/**
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* Show 0-32 bits. |
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*/ |
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static inline unsigned int show_bits_long(GetBitContext *s, int n){ |
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if (n <= MIN_CACHE_BITS) return show_bits(s, n); |
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static inline unsigned int show_bits_long(GetBitContext *s, int n) |
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{ |
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if (n <= MIN_CACHE_BITS) |
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return show_bits(s, n); |
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else { |
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GetBitContext gb = *s; |
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return get_bits_long(&gb, n); |
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@ -299,12 +333,9 @@ static inline int check_marker(GetBitContext *s, const char *msg) |
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* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger than the actual read bits |
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* because some optimized bitstream readers read 32 or 64 bit at once and could read over the end |
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* @param bit_size the size of the buffer in bits |
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* |
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* While GetBitContext stores the buffer size, for performance reasons you are |
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* responsible for checking for the buffer end yourself (take advantage of the padding)! |
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*/ |
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static inline void init_get_bits(GetBitContext *s, |
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const uint8_t *buffer, int bit_size) |
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static inline void init_get_bits(GetBitContext *s, const uint8_t *buffer, |
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int bit_size) |
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{ |
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int buffer_size = (bit_size+7)>>3; |
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if (buffer_size < 0 || bit_size < 0) { |
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@ -314,6 +345,7 @@ static inline void init_get_bits(GetBitContext *s, |
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s->buffer = buffer; |
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s->size_in_bits = bit_size; |
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s->size_in_bits_plus8 = bit_size + 8; |
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s->buffer_end = buffer + buffer_size; |
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s->index = 0; |
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} |
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@ -355,7 +387,8 @@ void free_vlc(VLC *vlc); |
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* If the vlc code is invalid and max_depth>1, then the number of bits removed |
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* is undefined. |
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*/ |
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#define GET_VLC(code, name, gb, table, bits, max_depth) do { \ |
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#define GET_VLC(code, name, gb, table, bits, max_depth) \ |
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do { \
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int n, nb_bits; \
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unsigned int index; \
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\
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@ -386,7 +419,8 @@ void free_vlc(VLC *vlc); |
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SKIP_BITS(name, gb, n); \
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} while (0) |
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#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update) do { \ |
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#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update) \ |
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do { \
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int n, nb_bits; \
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unsigned int index; \
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\
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@ -412,7 +446,7 @@ void free_vlc(VLC *vlc); |
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/**
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* Parse a vlc code, faster than get_vlc(). |
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* Parse a vlc code. |
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* @param bits is the number of bits which will be read at once, must be |
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* identical to nb_bits in init_vlc() |
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* @param max_depth is the number of times bits bits must be read to completely |
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@ -433,7 +467,8 @@ static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], |
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return code; |
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} |
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static inline int decode012(GetBitContext *gb){ |
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static inline int decode012(GetBitContext *gb) |
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{ |
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int n; |
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n = get_bits1(gb); |
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if (n == 0) |
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@ -442,7 +477,8 @@ static inline int decode012(GetBitContext *gb){ |
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return get_bits1(gb) + 1; |
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} |
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static inline int decode210(GetBitContext *gb){ |
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static inline int decode210(GetBitContext *gb) |
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{ |
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if (get_bits1(gb)) |
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return 0; |
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else |
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@ -457,7 +493,8 @@ static inline int get_bits_left(GetBitContext *gb) |
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//#define TRACE
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#ifdef TRACE |
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static inline void print_bin(int bits, int n){ |
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static inline void print_bin(int bits, int n) |
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{ |
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int i; |
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for (i = n-1; i >= 0; i--) { |
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@ -468,7 +505,8 @@ static inline void print_bin(int bits, int n){ |
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} |
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static inline int get_bits_trace(GetBitContext *s, int n, char *file, |
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const char *func, int line){ |
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const char *func, int line) |
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{ |
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int r = get_bits(s, n); |
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print_bin(r, n); |
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@ -478,7 +516,8 @@ static inline int get_bits_trace(GetBitContext *s, int n, char *file, |
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} |
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static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], |
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int bits, int max_depth, char *file, |
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const char *func, int line){ |
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const char *func, int line) |
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{ |
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int show = show_bits(s, 24); |
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int pos = get_bits_count(s); |
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int r = get_vlc2(s, table, bits, max_depth); |
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@ -492,7 +531,8 @@ static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], |
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return r; |
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} |
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static inline int get_xbits_trace(GetBitContext *s, int n, char *file, |
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const char *func, int line){ |
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const char *func, int line) |
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{ |
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int show = show_bits(s, n); |
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int r = get_xbits(s, n); |
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