see.c

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/* Copyright 2013 Jorge Merlino

   This file is part of Context.

   Context 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 3 of the License, or
   (at your option) any later version.

   Context 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 Context.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include <assert.h>
#include <math.h> /* for log */
#include "see.h"
#include "debug.h"

static int get3ByteRepresentation (const Uint num, const Uint alphasize) {
  if (num <= 0) return 0;
  else if (num <= 1) return 1;
  else if (num <= 2) return 2;
  else if (num <= 4) return 3;
  else if (num <= (alphasize >= 150 ? 8 : 6)) return 4; 
  else if (num <= 9) return 5;
  else if (num <= (alphasize >= 150 ? 25 : 15)) return 6; 
  else return 7;
}

int getSeeStateEncoder (fsmTree_t tree, Uint allCount, Uint pos, Uint numMasked, const Uchar * text, Uint alphasize) {
  Uint state, syms; 

  if (allCount >= (alphasize >= 150 ? 128 : 30)) {
    return -1;
  }

  state = get3ByteRepresentation(tree->totalCount - allCount, alphasize); /* escapes */

  state <<= 3;
  state |= get3ByteRepresentation(allCount, alphasize);

  state <<= 3;
  state |= get3ByteRepresentation(numMasked, alphasize);

  syms = tree->totalSyms;

  if (alphasize < 150) {
    while (!isRootFsmTree(tree) && tree->totalSyms == syms) {
      tree = tree->parent->origin;
    }
    state <<=2;
    if (tree->totalSyms > 3) {
      state |= 3;
    }
    else {
      state |= tree->totalSyms;
    }
  }

  state <<=3;
  if ((pos > 0) && (text[pos-1] > 0)) {
    state |= (int)(log(text[pos-1])+0.5);
  }

  return state;
}

int getSeeStateDecoder (decoderTree_t tree, Uint allCount, Uint pos, Uint numMasked, const Uchar * text, Uint alphasize) {
  Uint state, syms;

  if (allCount >= (alphasize >= 150 ? 128 : 30)) {
    return -1;
  }

  state = get3ByteRepresentation(tree->totalCount - allCount, alphasize);

  state <<= 3;
  state |= get3ByteRepresentation(allCount, alphasize);

  state <<=3;
  state |= get3ByteRepresentation(numMasked, alphasize);
  
  syms = tree->totalSyms;

  if (alphasize < 150) {
    while (!isRootDecoderTree(tree) && tree->totalSyms == syms) {
      tree = tree->parent->origin;
    }
    state <<=2;
    if (tree->totalSyms > 3) {
      state |= 3;
    }
    else {
      state |= tree->totalSyms;
    }
  }

  state <<=3;
  if ((pos > 0) && (text[pos-1] > 0)) {
    state |= (int)(log(text[pos-1])+0.5);
  }

  return state;
}
  
void updateSee (Uint state, BOOL escape, Uint alphasize) {
  if (escape) {
    See[state][0] += 17;
    See[state][1] += 18;
  }
  else {
    if (See[state][0] >= (alphasize >= 100 ? 500 : 4000)) {
      See[state][0] = (See[state][0] >> 1) + 1;
      See[state][1] = (See[state][1] >> 1) + 1;
    }
    See[state][1] += (alphasize >= 100 ? 16 : 17);
  }

  if (See[state][1] >= (alphasize >= 100 ? 800 : 8000)) {
    See[state][0] = (See[state][0] >> 1) + 1;
    See[state][1] = (See[state][1] >> 1) + 1;
  }
}

void initSee () {
  int i=0;

  for (i=0; i< 1<<14; i++) {
    See[i][0]=20;
    See[i][1]=50;
  }
}