From ca079b0954997affe4df8cf3120197875f75f3d7 Mon Sep 17 00:00:00 2001 From: Paul B Mahol Date: Fri, 7 Jul 2017 16:56:10 +0200 Subject: avcodec/get_bits: add cached bitstream reader Signed-off-by: Paul B Mahol --- libavcodec/get_bits.h | 218 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 216 insertions(+), 2 deletions(-) (limited to 'libavcodec/get_bits.h') diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h index 56ef5f0cbe..58ebb64656 100644 --- a/libavcodec/get_bits.h +++ b/libavcodec/get_bits.h @@ -1,5 +1,6 @@ /* - * copyright (c) 2004 Michael Niedermayer + * Copyright (c) 2004 Michael Niedermayer + * Copyright (c) 2016 Alexandra Hájková * * This file is part of FFmpeg. * @@ -55,11 +56,19 @@ typedef struct GetBitContext { const uint8_t *buffer, *buffer_end; +#ifdef CACHED_BITSTREAM_READER + uint64_t cache; + unsigned bits_left; +#endif int index; int size_in_bits; int size_in_bits_plus8; } GetBitContext; +static inline unsigned int get_bits(GetBitContext *s, int n); +static inline void skip_bits(GetBitContext *s, int n); +static inline unsigned int show_bits(GetBitContext *s, int n); + /* Bitstream reader API docs: * name * arbitrary name which is used as prefix for the internal variables @@ -107,12 +116,16 @@ typedef struct GetBitContext { * For examples see get_bits, show_bits, skip_bits, get_vlc. */ -#ifdef LONG_BITSTREAM_READER +#ifdef CACHED_BITSTREAM_READER +# define MIN_CACHE_BITS 64 +#elif defined LONG_BITSTREAM_READER # define MIN_CACHE_BITS 32 #else # define MIN_CACHE_BITS 25 #endif +#ifndef CACHED_BITSTREAM_READER + #define OPEN_READER_NOSIZE(name, gb) \ unsigned int name ## _index = (gb)->index; \ unsigned int av_unused name ## _cache @@ -197,11 +210,75 @@ typedef struct GetBitContext { #define GET_CACHE(name, gb) ((uint32_t) name ## _cache) +#endif + static inline int get_bits_count(const GetBitContext *s) { +#ifdef CACHED_BITSTREAM_READER + return s->index - s->bits_left; +#else return s->index; +#endif +} + +#ifdef CACHED_BITSTREAM_READER +static inline void refill_32(GetBitContext *s) +{ +#if !UNCHECKED_BITSTREAM_READER + if (s->index >> 3 >= s->buffer_end - s->buffer) + return; +#endif + +#ifdef BITSTREAM_READER_LE + s->cache = (uint64_t)AV_RL32(s->buffer + (s->index >> 3)) << s->bits_left | s->cache; +#else + s->cache = s->cache | (uint64_t)AV_RB32(s->buffer + (s->index >> 3)) << (32 - s->bits_left); +#endif + s->index += 32; + s->bits_left += 32; } +static inline void refill_64(GetBitContext *s) +{ +#if !UNCHECKED_BITSTREAM_READER + if (s->index >> 3 >= s->buffer_end - s->buffer) + return; +#endif + +#ifdef BITSTREAM_READER_LE + s->cache = AV_RL64(s->buffer + (s->index >> 3)); +#else + s->cache = AV_RB64(s->buffer + (s->index >> 3)); +#endif + s->index += 64; + s->bits_left = 64; +} + +static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le) +{ + uint64_t ret; + av_assert2(n>0 && n<=63); + if (is_le) { + ret = s->cache & ((UINT64_C(1) << n) - 1); + s->cache >>= n; + } else { + ret = s->cache >> (64 - n); + s->cache <<= n; + } + s->bits_left -= n; + return ret; +} + +static inline unsigned show_val(const GetBitContext *s, unsigned n) +{ +#ifdef BITSTREAM_READER_LE + return s->cache & ((UINT64_C(1) << n) - 1); +#else + return s->cache >> (64 - n); +#endif +} +#endif + /** * Skips the specified number of bits. * @param n the number of bits to skip, @@ -211,13 +288,29 @@ static inline int get_bits_count(const GetBitContext *s) */ static inline void skip_bits_long(GetBitContext *s, int n) { +#ifdef CACHED_BITSTREAM_READER + skip_bits(s, n); +#else #if UNCHECKED_BITSTREAM_READER s->index += n; #else s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); #endif +#endif } +#ifdef CACHED_BITSTREAM_READER +static inline void skip_remaining(GetBitContext *s, unsigned n) +{ +#ifdef BITSTREAM_READER_LE + s->cache >>= n; +#else + s->cache <<= n; +#endif + s->bits_left -= n; +} +#endif + /** * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB). * if MSB not set it is negative @@ -225,6 +318,13 @@ static inline void skip_bits_long(GetBitContext *s, int n) */ static inline int get_xbits(GetBitContext *s, int n) { +#ifdef CACHED_BITSTREAM_READER + int32_t cache = show_bits(s, 32); + int sign = ~cache >> 31; + skip_remaining(s, n); + + return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign; +#else register int sign; register int32_t cache; OPEN_READER(re, s); @@ -235,8 +335,10 @@ static inline int get_xbits(GetBitContext *s, int n) LAST_SKIP_BITS(re, s, n); CLOSE_READER(re, s); return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; +#endif } +#ifndef CACHED_BITSTREAM_READER static inline int get_xbits_le(GetBitContext *s, int n) { register int sign; @@ -250,16 +352,22 @@ static inline int get_xbits_le(GetBitContext *s, int n) CLOSE_READER(re, s); return (zero_extend(sign ^ cache, n) ^ sign) - sign; } +#endif static inline int get_sbits(GetBitContext *s, int n) { register int tmp; +#ifdef CACHED_BITSTREAM_READER + av_assert2(n>0 && n<=25); + tmp = sign_extend(get_bits(s, n), n); +#else OPEN_READER(re, s); av_assert2(n>0 && n<=25); UPDATE_CACHE(re, s); tmp = SHOW_SBITS(re, s, n); LAST_SKIP_BITS(re, s, n); CLOSE_READER(re, s); +#endif return tmp; } @@ -269,12 +377,28 @@ static inline int get_sbits(GetBitContext *s, int n) static inline unsigned int get_bits(GetBitContext *s, int n) { register int tmp; +#ifdef CACHED_BITSTREAM_READER + + av_assert2(n>0 && n<=32); + if (n > s->bits_left) { + refill_32(s); + if (s->bits_left < 32) + s->bits_left = n; + } + +#ifdef BITSTREAM_READER_LE + tmp = get_val(s, n, 1); +#else + tmp = get_val(s, n, 0); +#endif +#else OPEN_READER(re, s); av_assert2(n>0 && n<=25); UPDATE_CACHE(re, s); tmp = SHOW_UBITS(re, s, n); LAST_SKIP_BITS(re, s, n); CLOSE_READER(re, s); +#endif return tmp; } @@ -288,6 +412,16 @@ static av_always_inline int get_bitsz(GetBitContext *s, int n) static inline unsigned int get_bits_le(GetBitContext *s, int n) { +#ifdef CACHED_BITSTREAM_READER + av_assert2(n>0 && n<=32); + if (n > s->bits_left) { + refill_32(s); + if (s->bits_left < 32) + s->bits_left = n; + } + + return get_val(s, n, 1); +#else register int tmp; OPEN_READER(re, s); av_assert2(n>0 && n<=25); @@ -296,6 +430,7 @@ static inline unsigned int get_bits_le(GetBitContext *s, int n) LAST_SKIP_BITS(re, s, n); CLOSE_READER(re, s); return tmp; +#endif } /** @@ -304,22 +439,59 @@ static inline unsigned int get_bits_le(GetBitContext *s, int n) static inline unsigned int show_bits(GetBitContext *s, int n) { register int tmp; +#ifdef CACHED_BITSTREAM_READER + if (n > s->bits_left) + refill_32(s); + + tmp = show_val(s, n); +#else OPEN_READER_NOSIZE(re, s); av_assert2(n>0 && n<=25); UPDATE_CACHE(re, s); tmp = SHOW_UBITS(re, s, n); +#endif return tmp; } static inline void skip_bits(GetBitContext *s, int n) { +#ifdef CACHED_BITSTREAM_READER + if (n < s->bits_left) + skip_remaining(s, n); + else { + n -= s->bits_left; + s->cache = 0; + s->bits_left = 0; + + if (n >= 64) { + unsigned skip = (n / 8) * 8; + + n -= skip; + s->index += skip; + } + refill_64(s); + if (n) + skip_remaining(s, n); + } +#else OPEN_READER(re, s); LAST_SKIP_BITS(re, s, n); CLOSE_READER(re, s); +#endif } static inline unsigned int get_bits1(GetBitContext *s) { +#ifdef CACHED_BITSTREAM_READER + if (!s->bits_left) + refill_64(s); + +#ifdef BITSTREAM_READER_LE + return get_val(s, 1, 1); +#else + return get_val(s, 1, 0); +#endif +#else unsigned int index = s->index; uint8_t result = s->buffer[index >> 3]; #ifdef BITSTREAM_READER_LE @@ -336,6 +508,7 @@ static inline unsigned int get_bits1(GetBitContext *s) s->index = index; return result; +#endif } static inline unsigned int show_bits1(GetBitContext *s) @@ -356,6 +529,10 @@ static inline unsigned int get_bits_long(GetBitContext *s, int n) av_assert2(n>=0 && n<=32); if (!n) { return 0; +#ifdef CACHED_BITSTREAM_READER + } + return get_bits(s, n); +#else } else if (n <= MIN_CACHE_BITS) { return get_bits(s, n); } else { @@ -367,6 +544,7 @@ static inline unsigned int get_bits_long(GetBitContext *s, int n) return ret | get_bits(s, n - 16); #endif } +#endif } /** @@ -450,6 +628,10 @@ static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer, s->buffer_end = buffer + buffer_size; s->index = 0; +#ifdef CACHED_BITSTREAM_READER + refill_64(s); +#endif + return ret; } @@ -551,6 +733,19 @@ static inline const uint8_t *align_get_bits(GetBitContext *s) SKIP_BITS(name, gb, n); \ } while (0) +/* Return the LUT element for the given bitstream configuration. */ +static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits, + VLC_TYPE (*table)[2]) +{ + unsigned idx; + + *nb_bits = -*n; + idx = show_bits(s, *nb_bits) + code; + *n = table[idx][1]; + + return table[idx][0]; +} + /** * Parse a vlc code. * @param bits is the number of bits which will be read at once, must be @@ -563,6 +758,24 @@ static inline const uint8_t *align_get_bits(GetBitContext *s) static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth) { +#ifdef CACHED_BITSTREAM_READER + int nb_bits; + unsigned idx = show_bits(s, bits); + int code = table[idx][0]; + int n = table[idx][1]; + + if (max_depth > 1 && n < 0) { + skip_remaining(s, bits); + code = set_idx(s, code, &n, &nb_bits, table); + if (max_depth > 2 && n < 0) { + skip_remaining(s, nb_bits); + code = set_idx(s, code, &n, &nb_bits, table); + } + } + skip_remaining(s, n); + + return code; +#else int code; OPEN_READER(re, s); @@ -573,6 +786,7 @@ static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], CLOSE_READER(re, s); return code; +#endif } static inline int decode012(GetBitContext *gb) -- cgit v1.2.3