/*
  * 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 */