libavcodec/cabac.h - third_party/ffmpeg - Git at Google

 /*
  * 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.
  */

 #ifndef AVCODEC_CABAC_H
 #define AVCODEC_CABAC_H

 #include <stddef.h>

 #include "put_bits.h"

 //#undef NDEBUG
 #include <assert.h>

 #define CABAC_BITS 16
 #define CABAC_MASK ((1<<CABAC_BITS)-1)

 typedef struct CABACContext{
     int low;
     int range;
     int outstanding_count;
 #ifdef STRICT_LIMITS
     int symCount;
 #endif
     const uint8_t *bytestream_start;
     const uint8_t *bytestream;
     const uint8_t *bytestream_end;
     PutBitContext pb;
 }CABACContext;

 extern uint8_t ff_h264_mlps_state[4*64];
 extern uint8_t ff_h264_lps_range[4*2*64];  ///< rangeTabLPS
 extern uint8_t ff_h264_mps_state[2*64];     ///< transIdxMPS
 extern uint8_t ff_h264_lps_state[2*64];     ///< transIdxLPS
 extern const uint8_t ff_h264_norm_shift[512];

 #if ARCH_X86
 #   include "x86/cabac.h"
 #endif

 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size);
 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size);
 void ff_init_cabac_states(CABACContext *c);


 static inline void put_cabac_bit(CABACContext *c, int b){
     put_bits(&c->pb, 1, b);
     for(;c->outstanding_count; c->outstanding_count--){
         put_bits(&c->pb, 1, 1-b);
     }
 }

 static inline void renorm_cabac_encoder(CABACContext *c){
     while(c->range < 0x100){
         //FIXME optimize
         if(c->low<0x100){
             put_cabac_bit(c, 0);
         }else if(c->low<0x200){
             c->outstanding_count++;
             c->low -= 0x100;
         }else{
             put_cabac_bit(c, 1);
             c->low -= 0x200;
         }

         c->range+= c->range;
         c->low += c->low;
     }
 }

 #ifdef TEST
 static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
     int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];

     if(bit == ((*state)&1)){
         c->range -= RangeLPS;
         *state= ff_h264_mps_state[*state];
     }else{
         c->low += c->range - RangeLPS;
         c->range = RangeLPS;
         *state= ff_h264_lps_state[*state];
     }

     renorm_cabac_encoder(c);

 #ifdef STRICT_LIMITS
     c->symCount++;
 #endif
 }

 static void put_cabac_static(CABACContext *c, int RangeLPS, int bit){
     assert(c->range > RangeLPS);

     if(!bit){
         c->range -= RangeLPS;
     }else{
         c->low += c->range - RangeLPS;
         c->range = RangeLPS;
     }

     renorm_cabac_encoder(c);

 #ifdef STRICT_LIMITS
     c->symCount++;
 #endif
 }

 /**
  * @param bit 0 -> write zero bit, !=0 write one bit
  */
 static void put_cabac_bypass(CABACContext *c, int bit){
     c->low += c->low;

     if(bit){
         c->low += c->range;
     }
 //FIXME optimize
     if(c->low<0x200){
         put_cabac_bit(c, 0);
     }else if(c->low<0x400){
         c->outstanding_count++;
         c->low -= 0x200;
     }else{
         put_cabac_bit(c, 1);
         c->low -= 0x400;
     }

 #ifdef STRICT_LIMITS
     c->symCount++;
 #endif
 }

 /**
  *
  * @return the number of bytes written
  */
 static int put_cabac_terminate(CABACContext *c, int bit){
     c->range -= 2;

     if(!bit){
         renorm_cabac_encoder(c);
     }else{
         c->low += c->range;
         c->range= 2;

         renorm_cabac_encoder(c);

         assert(c->low <= 0x1FF);
         put_cabac_bit(c, c->low>>9);
         put_bits(&c->pb, 2, ((c->low>>7)&3)|1);

         flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
     }

 #ifdef STRICT_LIMITS
     c->symCount++;
 #endif

     return (put_bits_count(&c->pb)+7)>>3;
 }

 /**
  * put (truncated) unary binarization.
  */
 static void put_cabac_u(CABACContext *c, uint8_t * state, int v, int max, int max_index, int truncated){
     int i;

     assert(v <= max);

 #if 1
     for(i=0; i<v; i++){
         put_cabac(c, state, 1);
         if(i < max_index) state++;
     }
     if(truncated==0 || v<max)
         put_cabac(c, state, 0);
 #else
     if(v <= max_index){
         for(i=0; i<v; i++){
             put_cabac(c, state+i, 1);
         }
         if(truncated==0 || v<max)
             put_cabac(c, state+i, 0);
     }else{
         for(i=0; i<=max_index; i++){
             put_cabac(c, state+i, 1);
         }
         for(; i<v; i++){
             put_cabac(c, state+max_index, 1);
         }
         if(truncated==0 || v<max)
             put_cabac(c, state+max_index, 0);
     }
 #endif
 }

 /**
  * put unary exp golomb k-th order binarization.
  */
 static void put_cabac_ueg(CABACContext *c, uint8_t * state, int v, int max, int is_signed, int k, int max_index){
     int i;

     if(v==0)
         put_cabac(c, state, 0);
     else{
         const int sign= v < 0;

         if(is_signed) v= FFABS(v);

         if(v<max){
             for(i=0; i<v; i++){
                 put_cabac(c, state, 1);
                 if(i < max_index) state++;
             }

             put_cabac(c, state, 0);
         }else{
             int m= 1<<k;

             for(i=0; i<max; i++){
                 put_cabac(c, state, 1);
                 if(i < max_index) state++;
             }

             v -= max;
             while(v >= m){ //FIXME optimize
                 put_cabac_bypass(c, 1);
                 v-= m;
                 m+= m;
             }
             put_cabac_bypass(c, 0);
             while(m>>=1){
                 put_cabac_bypass(c, v&m);
             }
         }

         if(is_signed)
             put_cabac_bypass(c, sign);
     }
 }
 #endif /* TEST */

 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;
     c->bytestream+= CABAC_BITS/8;
 }

 static inline void renorm_cabac_decoder(CABACContext *c){
     while(c->range < 0x100){
         c->range+= c->range;
         c->low+= c->low;
         if(!(c->low & CABAC_MASK))
             refill(c);
     }
 }

 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;
     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);
 }

 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;
     }
 }


 #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;
     }
 }

 #if 0
 /**
  * Get (truncated) unary binarization.
  */
 static int get_cabac_u(CABACContext *c, uint8_t * state, int max, int max_index, int truncated){
     int i;

     for(i=0; i<max; i++){
         if(get_cabac(c, state)==0)
             return i;

         if(i< max_index) state++;
     }

     return truncated ? max : -1;
 }

 /**
  * get unary exp golomb k-th order binarization.
  */
 static int get_cabac_ueg(CABACContext *c, uint8_t * state, int max, int is_signed, int k, int max_index){
     int i, v;
     int m= 1<<k;

     if(get_cabac(c, state)==0)
         return 0;

     if(0 < max_index) state++;

     for(i=1; i<max; i++){
         if(get_cabac(c, state)==0){
             if(is_signed && get_cabac_bypass(c)){
                 return -i;
             }else
                 return i;
         }

         if(i < max_index) state++;
     }

     while(get_cabac_bypass(c)){
         i+= m;
         m+= m;
     }

     v=0;
     while(m>>=1){
         v+= v + get_cabac_bypass(c);
     }
     i += v;

     if(is_signed && get_cabac_bypass(c)){
         return -i;
     }else
         return i;
 }
 #endif /* 0 */

 #endif /* AVCODEC_CABAC_H */
	/*
	* 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.
	*/

	#ifndef AVCODEC_CABAC_H
	#define AVCODEC_CABAC_H

	#include <stddef.h>

	#include "put_bits.h"

	//#undef NDEBUG
	#include <assert.h>

	#define CABAC_BITS 16
	#define CABAC_MASK ((1<<CABAC_BITS)-1)

	typedef struct CABACContext{
	int low;
	int range;
	int outstanding_count;
	#ifdef STRICT_LIMITS
	int symCount;
	#endif
	const uint8_t *bytestream_start;
	const uint8_t *bytestream;
	const uint8_t *bytestream_end;
	PutBitContext pb;
	}CABACContext;

	extern uint8_t ff_h264_mlps_state[4*64];
	extern uint8_t ff_h264_lps_range[4264]; ///< rangeTabLPS
	extern uint8_t ff_h264_mps_state[2*64]; ///< transIdxMPS
	extern uint8_t ff_h264_lps_state[2*64]; ///< transIdxLPS
	extern const uint8_t ff_h264_norm_shift[512];

	#if ARCH_X86
	# include "x86/cabac.h"
	#endif

	void ff_init_cabac_encoder(CABACContext c, uint8_t buf, int buf_size);
	void ff_init_cabac_decoder(CABACContext c, const uint8_t buf, int buf_size);
	void ff_init_cabac_states(CABACContext *c);


	static inline void put_cabac_bit(CABACContext *c, int b){
	put_bits(&c->pb, 1, b);
	for(;c->outstanding_count; c->outstanding_count--){
	put_bits(&c->pb, 1, 1-b);
	}
	}

	static inline void renorm_cabac_encoder(CABACContext *c){
	while(c->range < 0x100){
	//FIXME optimize
	if(c->low<0x100){
	put_cabac_bit(c, 0);
	}else if(c->low<0x200){
	c->outstanding_count++;
	c->low -= 0x100;
	}else{
	put_cabac_bit(c, 1);
	c->low -= 0x200;
	}

	c->range+= c->range;
	c->low += c->low;
	}
	}

	#ifdef TEST
	static void put_cabac(CABACContext c, uint8_t const state, int bit){
	int RangeLPS= ff_h264_lps_range[2(c->range&0xC0) + state];

	if(bit == ((*state)&1)){
	c->range -= RangeLPS;
	state= ff_h264_mps_state[state];
	}else{
	c->low += c->range - RangeLPS;
	c->range = RangeLPS;
	state= ff_h264_lps_state[state];
	}

	renorm_cabac_encoder(c);

	#ifdef STRICT_LIMITS
	c->symCount++;
	#endif
	}

	static void put_cabac_static(CABACContext *c, int RangeLPS, int bit){
	assert(c->range > RangeLPS);

	if(!bit){
	c->range -= RangeLPS;
	}else{
	c->low += c->range - RangeLPS;
	c->range = RangeLPS;
	}

	renorm_cabac_encoder(c);

	#ifdef STRICT_LIMITS
	c->symCount++;
	#endif
	}

	/**
	* @param bit 0 -> write zero bit, !=0 write one bit
	*/
	static void put_cabac_bypass(CABACContext *c, int bit){
	c->low += c->low;

	if(bit){
	c->low += c->range;
	}
	//FIXME optimize
	if(c->low<0x200){
	put_cabac_bit(c, 0);
	}else if(c->low<0x400){
	c->outstanding_count++;
	c->low -= 0x200;
	}else{
	put_cabac_bit(c, 1);
	c->low -= 0x400;
	}

	#ifdef STRICT_LIMITS
	c->symCount++;
	#endif
	}

	/**
	*
	* @return the number of bytes written
	*/
	static int put_cabac_terminate(CABACContext *c, int bit){
	c->range -= 2;

	if(!bit){
	renorm_cabac_encoder(c);
	}else{
	c->low += c->range;
	c->range= 2;

	renorm_cabac_encoder(c);

	assert(c->low <= 0x1FF);
	put_cabac_bit(c, c->low>>9);
	put_bits(&c->pb, 2, ((c->low>>7)&3)\|1);

	flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
	}

	#ifdef STRICT_LIMITS
	c->symCount++;
	#endif

	return (put_bits_count(&c->pb)+7)>>3;
	}

	/**
	* put (truncated) unary binarization.
	*/
	static void put_cabac_u(CABACContext c, uint8_t state, int v, int max, int max_index, int truncated){
	int i;

	assert(v <= max);

	#if 1
	for(i=0; i<v; i++){
	put_cabac(c, state, 1);
	if(i < max_index) state++;
	}
	if(truncated==0 \|\| v<max)
	put_cabac(c, state, 0);
	#else
	if(v <= max_index){
	for(i=0; i<v; i++){
	put_cabac(c, state+i, 1);
	}
	if(truncated==0 \|\| v<max)
	put_cabac(c, state+i, 0);
	}else{
	for(i=0; i<=max_index; i++){
	put_cabac(c, state+i, 1);
	}
	for(; i<v; i++){
	put_cabac(c, state+max_index, 1);
	}
	if(truncated==0 \|\| v<max)
	put_cabac(c, state+max_index, 0);
	}
	#endif
	}

	/**
	* put unary exp golomb k-th order binarization.
	*/
	static void put_cabac_ueg(CABACContext c, uint8_t state, int v, int max, int is_signed, int k, int max_index){
	int i;

	if(v==0)
	put_cabac(c, state, 0);
	else{
	const int sign= v < 0;

	if(is_signed) v= FFABS(v);

	if(v<max){
	for(i=0; i<v; i++){
	put_cabac(c, state, 1);
	if(i < max_index) state++;
	}

	put_cabac(c, state, 0);
	}else{
	int m= 1<<k;

	for(i=0; i<max; i++){
	put_cabac(c, state, 1);
	if(i < max_index) state++;
	}

	v -= max;
	while(v >= m){ //FIXME optimize
	put_cabac_bypass(c, 1);
	v-= m;
	m+= m;
	}
	put_cabac_bypass(c, 0);
	while(m>>=1){
	put_cabac_bypass(c, v&m);
	}
	}

	if(is_signed)
	put_cabac_bypass(c, sign);
	}
	}
	#endif /* TEST */

	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;
	c->bytestream+= CABAC_BITS/8;
	}

	static inline void renorm_cabac_decoder(CABACContext *c){
	while(c->range < 0x100){
	c->range+= c->range;
	c->low+= c->low;
	if(!(c->low & CABAC_MASK))
	refill(c);
	}
	}

	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;
	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);
	}

	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;
	}
	}


	#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;
	}
	}

	#if 0
	/**
	* Get (truncated) unary binarization.
	*/
	static int get_cabac_u(CABACContext c, uint8_t state, int max, int max_index, int truncated){
	int i;

	for(i=0; i<max; i++){
	if(get_cabac(c, state)==0)
	return i;

	if(i< max_index) state++;
	}

	return truncated ? max : -1;
	}

	/**
	* get unary exp golomb k-th order binarization.
	*/
	static int get_cabac_ueg(CABACContext c, uint8_t state, int max, int is_signed, int k, int max_index){
	int i, v;
	int m= 1<<k;

	if(get_cabac(c, state)==0)
	return 0;

	if(0 < max_index) state++;

	for(i=1; i<max; i++){
	if(get_cabac(c, state)==0){
	if(is_signed && get_cabac_bypass(c)){
	return -i;
	}else
	return i;
	}

	if(i < max_index) state++;
	}

	while(get_cabac_bypass(c)){
	i+= m;
	m+= m;
	}

	v=0;
	while(m>>=1){
	v+= v + get_cabac_bypass(c);
	}
	i += v;

	if(is_signed && get_cabac_bypass(c)){
	return -i;
	}else
	return i;
	}
	#endif /* 0 */

	#endif /* AVCODEC_CABAC_H */