path: root/encoder.h

/*  Lzlib - Compression library for the lzip format
    Copyright (C) 2009-2015 Antonio Diaz Diaz.

    This library is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    This library 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this library.  If not, see <http://www.gnu.org/licenses/>.

    As a special exception, you may use this file as part of a free
    software library without restriction.  Specifically, if other files
    instantiate templates or use macros or inline functions from this
    file, or you compile this file and link it with other files to
    produce an executable, this file does not by itself cause the
    resulting executable to be covered by the GNU General Public
    License.  This exception does not however invalidate any other
    reasons why the executable file might be covered by the GNU General
    Public License.
*/

struct Len_prices
  {
  const struct Len_model * lm;
  int len_symbols;
  int count;
  int prices[pos_states][max_len_symbols];
  int counters[pos_states];
  };

static inline void Lp_update_low_mid_prices( struct Len_prices * const lp,
                                             const int pos_state )
  {
  int * const pps = lp->prices[pos_state];
  int tmp = price0( lp->lm->choice1 );
  int len = 0;
  lp->counters[pos_state] = lp->count;
  for( ; len < len_low_symbols && len < lp->len_symbols; ++len )
    pps[len] = tmp + price_symbol( lp->lm->bm_low[pos_state], len, len_low_bits );
  if( len >= lp->len_symbols ) return;
  tmp = price1( lp->lm->choice1 ) + price0( lp->lm->choice2 );
  for( ; len < len_low_symbols + len_mid_symbols && len < lp->len_symbols; ++len )
    pps[len] = tmp +
               price_symbol( lp->lm->bm_mid[pos_state], len - len_low_symbols, len_mid_bits );
    }

static inline void Lp_update_high_prices( struct Len_prices * const lp )
  {
  const int tmp = price1( lp->lm->choice1 ) + price1( lp->lm->choice2 );
  int len;
  for( len = len_low_symbols + len_mid_symbols; len < lp->len_symbols; ++len )
    /* using 4 slots per value makes "Lp_price" faster */
    lp->prices[3][len] = lp->prices[2][len] =
    lp->prices[1][len] = lp->prices[0][len] = tmp +
      price_symbol( lp->lm->bm_high, len - len_low_symbols - len_mid_symbols, len_high_bits );
  }

static inline void Lp_reset( struct Len_prices * const lp )
  { int i; for( i = 0; i < pos_states; ++i ) lp->counters[i] = 0; }

static inline void Lp_init( struct Len_prices * const lp,
                            const struct Len_model * const lm,
                            const int match_len_limit )
  {
  lp->lm = lm;
  lp->len_symbols = match_len_limit + 1 - min_match_len;
  lp->count = ( match_len_limit > 12 ) ? 1 : lp->len_symbols;
  Lp_reset( lp );
  }

static inline void Lp_decrement_counter( struct Len_prices * const lp,
                                         const int pos_state )
  { --lp->counters[pos_state]; }

static inline void Lp_update_prices( struct Len_prices * const lp )
  {
  int pos_state;
  bool high_pending = false;
  for( pos_state = 0; pos_state < pos_states; ++pos_state )
    if( lp->counters[pos_state] <= 0 )
      { Lp_update_low_mid_prices( lp, pos_state ); high_pending = true; }
  if( high_pending && lp->len_symbols > len_low_symbols + len_mid_symbols )
    Lp_update_high_prices( lp );
  }

static inline int Lp_price( const struct Len_prices * const lp,
                            const int symbol, const int pos_state )
  { return lp->prices[pos_state][symbol - min_match_len]; }


struct Pair			/* distance-length pair */
  {
  int dis;
  int len;
  };

enum { infinite_price = 0x0FFFFFFF,
       max_num_trials = 1 << 13,
       single_step_trial = -2,
       dual_step_trial = -1 };

struct Trial
  {
  State state;
  int price;		/* dual use var; cumulative price, match length */
  int dis;		/* rep index or match distance. (-1 for literal) */
  int prev_index;	/* index of prev trial in trials[] */
  int prev_index2;	/*   -2  trial is single step */
			/*   -1  literal + rep0 */
			/* >= 0  ( rep or match ) + literal + rep0 */
  int reps[num_rep_distances];
  };

static inline void Tr_update( struct Trial * const trial, const int pr,
                              const int distance, const int p_i )
  {
  if( pr < trial->price )
    {
    trial->price = pr; trial->dis = distance; trial->prev_index = p_i;
    trial->prev_index2 = single_step_trial;
    }
  }

static inline void Tr_update2( struct Trial * const trial, const int pr,
                               const int p_i )
  {
  if( pr < trial->price )
    {
    trial->price = pr; trial->dis = 0; trial->prev_index = p_i;
    trial->prev_index2 = dual_step_trial;
    }
  }

static inline void Tr_update3( struct Trial * const trial, const int pr,
                               const int distance, const int p_i,
                               const int p_i2 )
  {
  if( pr < trial->price )
    {
    trial->price = pr; trial->dis = distance; trial->prev_index = p_i;
    trial->prev_index2 = p_i2;
    }
  }


struct LZ_encoder
  {
  struct LZ_encoder_base eb;
  int cycles;
  int match_len_limit;
  struct Len_prices match_len_prices;
  struct Len_prices rep_len_prices;
  int pending_num_pairs;
  struct Pair pairs[max_match_len+1];
  struct Trial trials[max_num_trials];

  int dis_slot_prices[len_states][2*max_dictionary_bits];
  int dis_prices[len_states][modeled_distances];
  int align_prices[dis_align_size];
  int num_dis_slots;
  int price_counter;
  int dis_price_counter;
  int align_price_counter;
  bool been_flushed;
  };

static inline bool Mb_dec_pos( struct Matchfinder_base * const mb,
                               const int ahead )
  {
  if( ahead < 0 || mb->pos < ahead ) return false;
  mb->pos -= ahead;
  mb->cyclic_pos -= ahead;
  if( mb->cyclic_pos < 0 ) mb->cyclic_pos += mb->dictionary_size + 1;
  return true;
  }

static int LZe_get_match_pairs( struct LZ_encoder * const e, struct Pair * pairs );

       /* move-to-front dis in/into reps if( dis > 0 ) */
static inline void mtf_reps( const int dis, int reps[num_rep_distances] )
  {
  int i;
  if( dis >= num_rep_distances )
    {
    for( i = num_rep_distances - 1; i > 0; --i ) reps[i] = reps[i-1];
    reps[0] = dis - num_rep_distances;
    }
  else if( dis > 0 )
    {
    const int distance = reps[dis];
    for( i = dis; i > 0; --i ) reps[i] = reps[i-1];
    reps[0] = distance;
    }
  }

static inline int LZeb_price_shortrep( const struct LZ_encoder_base * const eb,
                                       const State state, const int pos_state )
  {
  return price0( eb->bm_rep0[state] ) + price0( eb->bm_len[state][pos_state] );
  }

static inline int LZeb_price_rep( const struct LZ_encoder_base * const eb,
                                  const int rep,
                                  const State state, const int pos_state )
  {
  int price;
  if( rep == 0 ) return price0( eb->bm_rep0[state] ) +
                        price1( eb->bm_len[state][pos_state] );
  price = price1( eb->bm_rep0[state] );
  if( rep == 1 )
    price += price0( eb->bm_rep1[state] );
  else
    {
    price += price1( eb->bm_rep1[state] );
    price += price_bit( eb->bm_rep2[state], rep - 2 );
    }
  return price;
  }

static inline int LZe_price_rep0_len( const struct LZ_encoder * const e,
                                      const int len,
                                      const State state, const int pos_state )
  {
  return LZeb_price_rep( &e->eb, 0, state, pos_state ) +
         Lp_price( &e->rep_len_prices, len, pos_state );
  }

static inline int LZe_price_pair( const struct LZ_encoder * const e,
                                  const int dis, const int len,
                                  const int pos_state )
  {
  const int price = Lp_price( &e->match_len_prices, len, pos_state );
  const int len_state = get_len_state( len );
  if( dis < modeled_distances )
    return price + e->dis_prices[len_state][dis];
  else
    return price + e->dis_slot_prices[len_state][get_slot( dis )] +
           e->align_prices[dis & (dis_align_size - 1)];
  }

static inline int LZe_read_match_distances( struct LZ_encoder * const e )
  {
  const int num_pairs = LZe_get_match_pairs( e, e->pairs );
  if( num_pairs > 0 )
    {
    int len = e->pairs[num_pairs-1].len;
    if( len == e->match_len_limit && len < max_match_len )
      {
      len += Mb_true_match_len( &e->eb.mb, len, e->pairs[num_pairs-1].dis + 1,
                                max_match_len - len );
      e->pairs[num_pairs-1].len = len;
      }
    }
  return num_pairs;
  }

static inline bool LZe_move_and_update( struct LZ_encoder * const e, int n )
  {
  while( true )
    {
    if( !Mb_move_pos( &e->eb.mb ) ) return false;
    if( --n <= 0 ) break;
    LZe_get_match_pairs( e, 0 );
    }
  return true;
  }

static inline void LZe_backward( struct LZ_encoder * const e, int cur )
  {
  int * const dis = &e->trials[cur].dis;
  while( cur > 0 )
    {
    const int prev_index = e->trials[cur].prev_index;
    struct Trial * const prev_trial = &e->trials[prev_index];

    if( e->trials[cur].prev_index2 != single_step_trial )
      {
      prev_trial->dis = -1;
      prev_trial->prev_index = prev_index - 1;
      prev_trial->prev_index2 = single_step_trial;
      if( e->trials[cur].prev_index2 >= 0 )
        {
        struct Trial * const prev_trial2 = &e->trials[prev_index-1];
        prev_trial2->dis = *dis; *dis = 0;
        prev_trial2->prev_index = e->trials[cur].prev_index2;
        prev_trial2->prev_index2 = single_step_trial;
        }
      }
    prev_trial->price = cur - prev_index;			/* len */
    cur = *dis; *dis = prev_trial->dis; prev_trial->dis = cur;
    cur = prev_index;
    }
  }

enum { num_prev_positions3 = 1 << 16,
       num_prev_positions2 = 1 << 10 };

static inline bool LZe_init( struct LZ_encoder * const e,
                             const int dict_size, const int len_limit,
                             const unsigned long long member_size )
  {
  enum { before = max_num_trials + 1,
         /* bytes to keep in buffer after pos */
         after_size = max_num_trials + ( 2 * max_match_len ) + 1,
         dict_factor = 2,
         num_prev_positions23 = num_prev_positions2 + num_prev_positions3,
         pos_array_factor = 2,
         min_free_bytes = 2 * max_num_trials };

  if( !LZeb_init( &e->eb, before, dict_size, after_size, dict_factor,
                  num_prev_positions23, pos_array_factor, min_free_bytes,
                  member_size ) ) return false;
  e->cycles = ( len_limit < max_match_len ) ? 16 + ( len_limit / 2 ) : 256;
  e->match_len_limit = len_limit;
  Lp_init( &e->match_len_prices, &e->eb.match_len_model, e->match_len_limit );
  Lp_init( &e->rep_len_prices, &e->eb.rep_len_model, e->match_len_limit );
  e->pending_num_pairs = 0;
  e->num_dis_slots = 2 * real_bits( e->eb.mb.dictionary_size - 1 );
  e->price_counter = 0;
  e->dis_price_counter = 0;
  e->align_price_counter = 0;
  e->been_flushed = false;
  return true;
  }

static inline void LZe_reset( struct LZ_encoder * const e,
                              const unsigned long long member_size )
  {
  LZeb_reset( &e->eb, member_size );
  Lp_reset( &e->match_len_prices );
  Lp_reset( &e->rep_len_prices );
  e->pending_num_pairs = 0;
  e->price_counter = 0;
  e->dis_price_counter = 0;
  e->align_price_counter = 0;
  e->been_flushed = false;
  }