0,0 → 1,189 |
/* |
* H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder |
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at> |
* |
* This file is part of FFmpeg. |
* |
* FFmpeg is free software; you can redistribute it and/or |
* modify it under the terms of the GNU Lesser General Public |
* License as published by the Free Software Foundation; either |
* version 2.1 of the License, or (at your option) any later version. |
* |
* FFmpeg is distributed in the hope that it will be useful, |
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
* Lesser General Public License for more details. |
* |
* You should have received a copy of the GNU Lesser General Public |
* License along with FFmpeg; if not, write to the Free Software |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
*/ |
|
/** |
* @file |
* Context Adaptive Binary Arithmetic Coder inline functions |
*/ |
|
#ifndef AVCODEC_CABAC_FUNCTIONS_H |
#define AVCODEC_CABAC_FUNCTIONS_H |
|
#include <stdint.h> |
|
#include "cabac.h" |
#include "config.h" |
|
#if ARCH_X86 |
# include "x86/cabac.h" |
#endif |
|
extern uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63]; |
static uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET; |
static uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET; |
static uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET; |
static uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET; |
|
static void refill(CABACContext *c){ |
#if CABAC_BITS == 16 |
c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); |
#else |
c->low+= c->bytestream[0]<<1; |
#endif |
c->low -= CABAC_MASK; |
#if !UNCHECKED_BITSTREAM_READER |
if (c->bytestream < c->bytestream_end) |
#endif |
c->bytestream += CABAC_BITS / 8; |
} |
|
static inline void renorm_cabac_decoder_once(CABACContext *c){ |
int shift= (uint32_t)(c->range - 0x100)>>31; |
c->range<<= shift; |
c->low <<= shift; |
if(!(c->low & CABAC_MASK)) |
refill(c); |
} |
|
#ifndef get_cabac_inline |
static void refill2(CABACContext *c){ |
int i, x; |
|
x= c->low ^ (c->low-1); |
i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)]; |
|
x= -CABAC_MASK; |
|
#if CABAC_BITS == 16 |
x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); |
#else |
x+= c->bytestream[0]<<1; |
#endif |
|
c->low += x<<i; |
#if !UNCHECKED_BITSTREAM_READER |
if (c->bytestream < c->bytestream_end) |
#endif |
c->bytestream += CABAC_BITS/8; |
} |
|
static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){ |
int s = *state; |
int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s]; |
int bit, lps_mask; |
|
c->range -= RangeLPS; |
lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31; |
|
c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask; |
c->range += (RangeLPS - c->range) & lps_mask; |
|
s^=lps_mask; |
*state= (ff_h264_mlps_state+128)[s]; |
bit= s&1; |
|
lps_mask= ff_h264_norm_shift[c->range]; |
c->range<<= lps_mask; |
c->low <<= lps_mask; |
if(!(c->low & CABAC_MASK)) |
refill2(c); |
return bit; |
} |
#endif |
|
static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){ |
return get_cabac_inline(c,state); |
} |
|
static int av_unused get_cabac(CABACContext *c, uint8_t * const state){ |
return get_cabac_inline(c,state); |
} |
|
#ifndef get_cabac_bypass |
static int av_unused get_cabac_bypass(CABACContext *c){ |
int range; |
c->low += c->low; |
|
if(!(c->low & CABAC_MASK)) |
refill(c); |
|
range= c->range<<(CABAC_BITS+1); |
if(c->low < range){ |
return 0; |
}else{ |
c->low -= range; |
return 1; |
} |
} |
#endif |
|
#ifndef get_cabac_bypass_sign |
static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){ |
int range, mask; |
c->low += c->low; |
|
if(!(c->low & CABAC_MASK)) |
refill(c); |
|
range= c->range<<(CABAC_BITS+1); |
c->low -= range; |
mask= c->low >> 31; |
range &= mask; |
c->low += range; |
return (val^mask)-mask; |
} |
#endif |
|
/** |
* |
* @return the number of bytes read or 0 if no end |
*/ |
static int av_unused get_cabac_terminate(CABACContext *c){ |
c->range -= 2; |
if(c->low < c->range<<(CABAC_BITS+1)){ |
renorm_cabac_decoder_once(c); |
return 0; |
}else{ |
return c->bytestream - c->bytestream_start; |
} |
} |
|
/** |
* Skip @p n bytes and reset the decoder. |
* @return the address of the first skipped byte or NULL if there's less than @p n bytes left |
*/ |
static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) { |
const uint8_t *ptr = c->bytestream; |
|
if (c->low & 0x1) |
ptr--; |
#if CABAC_BITS == 16 |
if (c->low & 0x1FF) |
ptr--; |
#endif |
if ((int) (c->bytestream_end - ptr) < n) |
return NULL; |
ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n); |
|
return ptr; |
} |
|
#endif /* AVCODEC_CABAC_FUNCTIONS_H */ |