/*
  * 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.
  */
 
 #include <string.h>
 

 #include "libavutil/common.h"

 #include "libavutil/timer.h"

 #include "get_bits.h"

 #include "cabac.h"

 #include "cabac_functions.h"

 uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63] = {
  9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
  4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 };
 

 static const uint8_t lps_range[64][4]= {

 {128,176,208,240}, {128,167,197,227}, {128,158,187,216}, {123,150,178,205},
 {116,142,169,195}, {111,135,160,185}, {105,128,152,175}, {100,122,144,166},
 { 95,116,137,158}, { 90,110,130,150}, { 85,104,123,142}, { 81, 99,117,135},
 { 77, 94,111,128}, { 73, 89,105,122}, { 69, 85,100,116}, { 66, 80, 95,110},
 { 62, 76, 90,104}, { 59, 72, 86, 99}, { 56, 69, 81, 94}, { 53, 65, 77, 89},
 { 51, 62, 73, 85}, { 48, 59, 69, 80}, { 46, 56, 66, 76}, { 43, 53, 63, 72},
 { 41, 50, 59, 69}, { 39, 48, 56, 65}, { 37, 45, 54, 62}, { 35, 43, 51, 59},
 { 33, 41, 48, 56}, { 32, 39, 46, 53}, { 30, 37, 43, 50}, { 29, 35, 41, 48},
 { 27, 33, 39, 45}, { 26, 31, 37, 43}, { 24, 30, 35, 41}, { 23, 28, 33, 39},
 { 22, 27, 32, 37}, { 21, 26, 30, 35}, { 20, 24, 29, 33}, { 19, 23, 27, 31},
 { 18, 22, 26, 30}, { 17, 21, 25, 28}, { 16, 20, 23, 27}, { 15, 19, 22, 25},
 { 14, 18, 21, 24}, { 14, 17, 20, 23}, { 13, 16, 19, 22}, { 12, 15, 18, 21},
 { 12, 14, 17, 20}, { 11, 14, 16, 19}, { 11, 13, 15, 18}, { 10, 12, 15, 17},
 { 10, 12, 14, 16}, {  9, 11, 13, 15}, {  9, 11, 12, 14}, {  8, 10, 12, 14},
 {  8,  9, 11, 13}, {  7,  9, 11, 12}, {  7,  9, 10, 12}, {  7,  8, 10, 11},
 {  6,  8,  9, 11}, {  6,  7,  9, 10}, {  6,  7,  8,  9}, {  2,  2,  2,  2},
 };
 

 static const uint8_t mps_state[64]= {

   1, 2, 3, 4, 5, 6, 7, 8,
   9,10,11,12,13,14,15,16,
  17,18,19,20,21,22,23,24,
  25,26,27,28,29,30,31,32,
  33,34,35,36,37,38,39,40,
  41,42,43,44,45,46,47,48,
  49,50,51,52,53,54,55,56,
  57,58,59,60,61,62,62,63,
 };
 

 static const uint8_t lps_state[64]= {

   0, 0, 1, 2, 2, 4, 4, 5,
   6, 7, 8, 9, 9,11,11,12,
  13,13,15,15,16,16,18,18,
  19,19,21,21,22,22,23,24,
  24,25,26,26,27,27,28,29,
  29,30,30,30,31,32,32,33,
  33,33,34,34,35,35,35,36,
  36,36,37,37,37,38,38,63,
 };

 static const uint8_t last_coeff_flag_offset_8x8[63] = {
  0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
  5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8

 };

 /**
  *
  * @param buf_size size of buf in bits
  */
 void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){

     init_put_bits(&c->pb, buf, buf_size);

 
     c->low= 0;
     c->range= 0x1FE;
     c->outstanding_count= 0;
     c->pb.bit_left++; //avoids firstBitFlag
 }
 
 /**
  *
  * @param buf_size size of buf in bits
  */

 void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){

     c->bytestream_start=

     c->bytestream= buf;

     c->bytestream_end= buf + buf_size;

 #if CABAC_BITS == 16
     c->low =  (*c->bytestream++)<<18;
     c->low+=  (*c->bytestream++)<<10;
 #else
     c->low =  (*c->bytestream++)<<10;
 #endif
     c->low+= ((*c->bytestream++)<<2) + 2;

     c->range= 0x1FE;

 }
 

 void ff_init_cabac_states(void)
 {

     int i, j;

     static int initialized = 0;
 
     if (initialized)
         return;

     for(i=0; i<64; i++){

         for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save

             ff_h264_lps_range[j*2*64+2*i+0]=
             ff_h264_lps_range[j*2*64+2*i+1]= lps_range[i][j];

         }

         ff_h264_mlps_state[128 + 2 * i + 0] = 2 * mps_state[i] + 0;
         ff_h264_mlps_state[128 + 2 * i + 1] = 2 * mps_state[i] + 1;

         if( i ){

             ff_h264_mlps_state[128-2*i-1]= 2*lps_state[i]+0;
             ff_h264_mlps_state[128-2*i-2]= 2*lps_state[i]+1;

         }else{

             ff_h264_mlps_state[128-2*i-1]= 1;
             ff_h264_mlps_state[128-2*i-2]= 0;

         }
     }

     for(i=0; i< 63; i++){
       ff_h264_last_coeff_flag_offset_8x8[i] = last_coeff_flag_offset_8x8[i];
     }

 
     initialized = 1;

 }
 

 #ifdef TEST

 #define SIZE 10240

 #include "libavutil/lfg.h"

 #include "avcodec.h"
 

 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;
     }
 }
 

 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_mlps_state[128 + *state];

     }else{
         c->low += c->range - RangeLPS;
         c->range = RangeLPS;

         *state= ff_h264_mlps_state[127 - *state];

     }
 
     renorm_cabac_encoder(c);
 }
 
 /**
  * @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;
     }
 }
 
 /**
  *
  * @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);
 

         av_assert0(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
     }
 
     return (put_bits_count(&c->pb)+7)>>3;
 }
 

 int main(void){

     CABACContext c;
     uint8_t b[9*SIZE];

     uint8_t r[9*SIZE];

     int i;

     uint8_t state[10]= {0};

     AVLFG prng;

     av_lfg_init(&prng, 1);

     ff_init_cabac_encoder(&c, b, SIZE);

     ff_init_cabac_states();

     for(i=0; i<SIZE; i++){

         if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
         else         r[i] = (i>>8)&1;

     }

     for(i=0; i<SIZE; i++){
 START_TIMER

         put_cabac_bypass(&c, r[i]&1);

 STOP_TIMER("put_cabac_bypass")
     }

     for(i=0; i<SIZE; i++){
 START_TIMER

         put_cabac(&c, state, r[i]&1);

 STOP_TIMER("put_cabac")
     }
 
     put_cabac_terminate(&c, 1);

     ff_init_cabac_decoder(&c, b, SIZE);

     memset(state, 0, sizeof(state));

     for(i=0; i<SIZE; i++){
 START_TIMER

         if( (r[i]&1) != get_cabac_bypass(&c) )

             av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);

 STOP_TIMER("get_cabac_bypass")
     }

     for(i=0; i<SIZE; i++){
 START_TIMER

         if( (r[i]&1) != get_cabac_noinline(&c, state) )

             av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);

 STOP_TIMER("get_cabac")
     }
     if(!get_cabac_terminate(&c))

         av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");

     return 0;
 }
 

 #endif /* TEST */