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+/*
+Copyright (C) 2004-2007 Christian Wieninger
+
+This program 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 program 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 program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+Or, point your browser to http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+
+The author can be reached at cwieninger@gmx.de
+
+The project's page is at http://winni.vdr-developer.org/epgsearch
+*/
+
+//---------------------------------------------------
+// Levenshtein Distance
+// by Michael Gilleland, Merriam Park Software
+//
+// source:
+// http://www.merriampark.com/ld.htm#CPLUSPLUS
+//
+//---------------------------------------------------
+
+#include "distance.h"
+#include <string.h>
+#include <malloc.h>
+#include <vdr/tools.h>
+
+
+//****************************
+// Get minimum of three values
+//****************************
+
+int Distance::Minimum (int a, int b, int c)
+{
+int mi;
+
+  mi = a;
+  if (b < mi) {
+    mi = b;
+  }
+  if (c < mi) {
+    mi = c;
+  }
+  return mi;
+
+}
+
+//**************************************************
+// Get a pointer to the specified cell of the matrix
+//************************************************** 
+
+int *Distance::GetCellPointer (int *pOrigin, int col, int row, int nCols)
+{
+  return pOrigin + col + (row * (nCols + 1));
+}
+
+//*****************************************************
+// Get the contents of the specified cell in the matrix 
+//*****************************************************
+
+int Distance::GetAt (int *pOrigin, int col, int row, int nCols)
+{
+int *pCell;
+
+  pCell = GetCellPointer (pOrigin, col, row, nCols);
+  return *pCell;
+
+}
+
+//*******************************************************
+// Fill the specified cell in the matrix with the value x
+//*******************************************************
+
+void Distance::PutAt (int *pOrigin, int col, int row, int nCols, int x)
+{
+int *pCell;
+
+  pCell = GetCellPointer (pOrigin, col, row, nCols);
+  *pCell = x;
+
+}
+
+//*****************************
+// Compute Levenshtein distance
+//*****************************
+
+int Distance::LD (char const *s, char const *t, int maxLength)
+{
+int *d; // pointer to matrix
+int n; // length of s
+int m; // length of t
+int i; // iterates through s
+int j; // iterates through t
+char s_i; // ith character of s
+char t_j; // jth character of t
+int cost; // cost
+int result; // result
+int cell; // contents of target cell
+int above; // contents of cell immediately above
+int left; // contents of cell immediately to left
+int diag; // contents of cell immediately above and to left
+int sz; // number of cells in matrix
+
+  // Step 1     
+
+  n = min((int)strlen(s), maxLength);
+  m = min((int)strlen(t), maxLength);
+  if (n == 0) {
+    return m;
+  }
+  if (m == 0) {
+    return n;
+  }
+  sz = (n+1) * (m+1) * sizeof (int);
+  d = (int *) malloc (sz);
+
+  // Step 2
+
+  for (i = 0; i <= n; i++) {
+    PutAt (d, i, 0, n, i);
+  }
+
+  for (j = 0; j <= m; j++) {
+    PutAt (d, 0, j, n, j);
+  }
+
+  // Step 3
+
+  for (i = 1; i <= n; i++) {
+
+    s_i = s[i-1];
+
+    // Step 4
+
+    for (j = 1; j <= m; j++) {
+
+      t_j = t[j-1];
+
+      // Step 5
+
+      if (s_i == t_j) {
+        cost = 0;
+      }
+      else {
+        cost = 1;
+      }
+
+      // Step 6 
+
+      above = GetAt (d,i-1,j, n);
+      left = GetAt (d,i, j-1, n);
+      diag = GetAt (d, i-1,j-1, n);
+      cell = Minimum (above + 1, left + 1, diag + cost);
+      PutAt (d, i, j, n, cell);
+    }
+  }
+
+  // Step 7
+
+  result = GetAt (d, n, m, n);
+  free (d);
+  return result;
+        
+}
+