dust.c

#include <math.h>
#include <ctype.h>
#include "dust.h"

void set_dust_level(value)
int value;
{
  level = value;
}

void set_dust_window(value)
int value;
{
  window = value;
  window2 = window / 2;
}

void set_dust_word(value)
int value;
{
  word = value;
}

static void wo1(len, s, ivv)
int len;
char *s;
int ivv;
{
  int i, ii, j, v, t, n, n1, sum;
  static int counts[32*32*32];
  static int iis[32*32*32];
  int js, nis;
  
  n = 32 * 32 * 32;
  n1 = n - 1;
  nis = 0;
  i = 0;
  ii = 0;
  sum = 0;
  v = 0;
  for (j=0; j < len; j++, s++) {
    ii <<= 5;
    if (isalpha(*s)) {
      if (islower(*s)) {
	ii |= *s - 'a';
      } else {
	ii |= *s - 'A';
      }
    } else {
      i = 0;
      continue;
    }
    ii &= n1;
    i++;
    if (i >= word) {
      for (js=0; js < nis && iis[js] != ii; js++) ;
      if (js == nis) {
	iis[nis] = ii;
	counts[ii] = 0;
	nis++;
      }
      if ((t = counts[ii]) > 0) {
	sum += t;
	v = 10 * sum / j;
	if (mv < v) {
	  mv = v;
	  iv = ivv;
	  jv = j;
	}
      }
      counts[ii]++;
    }
  }
}

static int wo(len, s, beg, end)
int len;
char *s;
int *beg, *end;
{
  int i, j, l1, v;
  
  l1 = len - word + 1;
  if (l1 < 0) {
    *beg = 0;
    *end = len - 1;
    return 0;
  }
  mv = 0;
  iv = 0;
  jv = 0;
  for (i=0; i < l1; i++) {
    wo1(len-i, s+i, i);
  }
  *beg = iv;
  *end = iv + jv;
  return mv;
}

void dust(len, s, sum)
int len;
char *s;
int *sum;
{
  int i, j, l, from, to, a, b, v;
  
  from = 0;
  to = -1;
  for (i=0; i < len; i += window2) {
    from -= window2;
    to -= window2;
    l = (len > i+window) ? window : len-i;
    v = wo(l, s+i, &a, &b);
    for (j = from; j <= to; j++) {
      if (isalpha(s[i+j]))
	//s[i+j] = tolower(s[i+j]); //'N';
	s[i+j] = 'N';
    }
    if (v > level) {
      for (j = a; j <= b && j < window2; j++) {
	if (isalpha(s[i+j])) {
	  //s[i+j] = tolower(s[i+j]); //'N';
	  s[i+j] = 'N';
	  (*sum)++;
	}
      }
      from = j;
      to = b;
    }
    else {
      from = 0;
      to = -1;
    }
  }
}

REGION *dust_segs(len, s)
int len;
char *s;
{
  int i, j, l, from, to, a, b, v;
  
  nreg = 0;
  from = 0;
  to = -1;
  for (i=0; i < len; i += window2) {
    l = (len > i+window) ? window : len-i;
    v = wo(l, s+i, &a, &b);
    if (v > level) {
      if (nreg > 0 && reg[nreg-1].to+1 >= a+i) {
	reg[nreg-1].to = b + i;
      } else if (nreg < MAXREG-1) {
	reg[nreg].from = a + i;
	reg[nreg].to = b + i;
	nreg++;
      }
      if (b < window2) {
	i += b - window2;
      }
    }
  }
  reg[nreg].from = 0;
  reg[nreg].to = -1;
  return reg;
}

REGION *dust_mix(len, s)
int len;
char *s;
{
  int i, j, l, from, to, a, b, v;
  
  nreg = 0;
  from = 0;
  to = -1;
  for (i=0; i < len; i += window2) {
    from -= window2;
    to -= window2;
    l = (len > i+window) ? window : len-i;
    v = wo(l, s+i, &a, &b);
    for (j = from; j <= to; j++) {
      if (isalpha(s[i+j]))
	s[i+j] = 'N';
    }
    if (v > level) {
      for (j = a; j <= b && j < window2; j++) {
	if (isalpha(s[i+j]))
	  s[i+j] = 'N';
      }
      
      from = j;
      to = b;
      
      if (nreg > 0 && reg[nreg-1].to+1 >= a+i) {
	reg[nreg-1].to = b + i;
      }
      else if (nreg < MAXREG-1) {
	reg[nreg].from = a + i;
	reg[nreg].to = b + i;
	nreg++;
      }
    }
    else {
      from = 0;
      to = -1;
    }
  }
  reg[nreg].from = 0;
  reg[nreg].to = -1;
  return reg;
}