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/*

 * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder

 * Copyright (c) 2003 Michael Niedermayer 

 *

 * 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 

#include "cabac.h"

#include "config.h"

#ifndef UNCHECKED_BITSTREAM_READER

#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER

#endif

#if ARCH_AARCH64

#   include "aarch64/cabac.h"

#endif

#if ARCH_ARM

#   include "arm/cabac.h"

#endif

#if ARCH_X86

#   include "x86/cabac.h"

#endif

static CABAC_TABLE_CONST uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;

static CABAC_TABLE_CONST uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;

static CABAC_TABLE_CONST uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET;

static CABAC_TABLE_CONST 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;

    unsigned 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<

#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;

    if (ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n) < 0)

        return NULL;

    return ptr;

}

#endif /* AVCODEC_CABAC_FUNCTIONS_H */