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C:/temp/src/j2k/Beta/Math/BitVector.cpp

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#ifndef __J2K__BitVector_CPP__
#define __J2K__BitVector_CPP__

#include <j2k/Fred/Math/BitVector.hpp>

// A byte with the high bit set:
const unsigned char highbit = 1 << (CHAR_BIT - 1);

BitVector::BitVector()
 : numBytes( 0 ), Bits( 0 ), bytes( NULL ) { }

// Notice default args are not duplicated:
BitVector::BitVector(UCHAR* init, int size)
 : numBytes( size ), Bits( numBytes * CHAR_BIT )
{
  bytes = (UCHAR*)calloc(numBytes, 1);
  assert( bytes );

  if ( init == NULL ) return; // Default to all 0

  // Translate from bytes into bit sequence:
  for( int index = 0; index < numBytes; index++)
    for( int offset = 0; offset < CHAR_BIT; offset++)
      if ( init[index] & (highbit >> offset) )
         set( index * CHAR_BIT + offset );
}

BitVector::BitVector( char* binary ) {
  Bits = strlen( binary );
  numBytes = Bits / CHAR_BIT;

  // If there's a remainder, add 1 byte:
  if ( Bits % CHAR_BIT ) numBytes++;

  bytes = (unsigned char*)calloc(numBytes, 1);
  assert(bytes);

  for(int i = 0; i < Bits; i++)
    if (binary[i] == '1') set(i);
}

BitVector::~BitVector() {
  free(bytes);
}

void BitVector::set(int bit) {
  assert(bit >= 0 && bit < Bits);
  int index  = bit / CHAR_BIT;
  int offset = bit % CHAR_BIT;
  UCHAR mask = (1 << offset);
  bytes[index] |= mask;
}

int BitVector::read(int bit) {
  assert(bit >= 0 && bit < Bits);
  int index  = bit / CHAR_BIT;
  int offset = bit % CHAR_BIT;
  UCHAR mask = (1 << offset);
  return bytes[index] & mask;
}

void BitVector::clear(int bit) {
  assert(bit >= 0 && bit < Bits);
  int index  = bit / CHAR_BIT;
  int offset = bit % CHAR_BIT;
  UCHAR mask = ~(1 << offset);
  bytes[index] &= mask;
}

int BitVector::bits() { return Bits; }

void BitVector::bits(int size) {
  int oldsize = Bits;
  Bits = size;
  numBytes =  Bits / CHAR_BIT;

  // If there's a remainder, add 1 byte:
  if ( Bits % CHAR_BIT ) numBytes++;

  void* v = realloc(bytes, numBytes);
  assert(v);

  bytes = (unsigned char*)v;

  for(int i = oldsize; i < Bits; i++)
    clear(i); // Erase additional bits
}

void BitVector::print(const char* msg) {
  puts(msg);

  for(int i = 0; i < Bits; i++){
    if ( read(i) ) {
      putchar('1');
    } else {
      putchar('0');
    }

    // Format into byte blocks:
    if((i + 1) % CHAR_BIT == 0) putchar(' ');
  }
  putchar('\n');
}


#endif

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