tesseract/cutil/bitvec.cpp

/******************************************************************************
 **	Filename:    bitvec.c
 **	Purpose:     Routines for manipulating bit vectors
 **	Author:      Dan Johnson
 **	History:     Thu Mar 15 10:37:27 1990, DSJ, Created.
 **
 **	(c) Copyright Hewlett-Packard Company, 1988.
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 ** http://www.apache.org/licenses/LICENSE-2.0
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 ******************************************************************************/

/*-----------------------------------------------------------------------------
          Include Files and Type Defines
-----------------------------------------------------------------------------*/
#include "bitvec.h"

#include <stdio.h>

#include "emalloc.h"
#include "freelist.h"
#include "tprintf.h"

/*-----------------------------------------------------------------------------
              Public Code
-----------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
/**
 * This routine uses realloc to increase the size of
 * the specified bit vector.
 *
 * Globals: 
 * - none
 *
 * @param Vector bit vector to be expanded
 * @param NewNumBits new size of bit vector
 *
 * @return New expanded bit vector.
 * @note Exceptions: none
 * @note History: Fri Nov 16 10:11:16 1990, DSJ, Created.
 */
BIT_VECTOR ExpandBitVector(BIT_VECTOR Vector, int NewNumBits) {
  return ((BIT_VECTOR) Erealloc(Vector,
    sizeof(Vector[0]) * WordsInVectorOfSize(NewNumBits)));
}                                /* ExpandBitVector */


/*---------------------------------------------------------------------------*/
void FreeBitVector(BIT_VECTOR BitVector) {
/**
 * This routine frees a bit vector.  It also decrements
 * the global counter that keeps track of the number of
 * bit vectors allocated.  If BitVector is NULL, then
 * the count is printed to stderr.
 *
 * Globals:
 * - BitVectorCount count of number of bit vectors allocated
 *
 * @param BitVector bit vector to be freed
 *
 * @note Exceptions: none
 * @note History: Tue Oct 23 16:46:09 1990, DSJ, Created.
 */
  if (BitVector) {
    Efree(BitVector);
  }
}                                /* FreeBitVector */


/**
 * hamming_distance(array1,array2,length) computes the hamming distance
 * between two bit strings.
 */
/*--------------------------------------------------------------------------*/
int hamming_distance(uinT32* array1, uinT32* array2, int length) {
  register uinT32 diff;   /*bit difference */
  register int dist;             /*total distance */

  dist = 0;
  for (; length > 0; length--) {
    diff = *array1++ ^ *array2++;/*different bits */
    while (diff) {
      diff &= diff - 1;          /*lose a bit */
      dist++;
    }
  }
  return dist;                   /*total distance */
}


/*---------------------------------------------------------------------------*/
/**
 * Allocate and return a new bit vector large enough to
 * hold the specified number of bits.
 *
 * Globals:
 * - BitVectorCount	number of bit vectors allocated
 *
 * @param NumBits number of bits in new bit vector
 *
 * @return New bit vector.
 * @note Exceptions: none
 * @note History: Tue Oct 23 16:51:27 1990, DSJ, Created.
 */
BIT_VECTOR NewBitVector(int NumBits) {
  return ((BIT_VECTOR) Emalloc(sizeof(uinT32) *
    WordsInVectorOfSize(NumBits)));
}                                /* NewBitVector */