zxing/csharp/common/BitArray.cs

using System;
using System.Collections;
using System.Text;

/*
 * Copyright 2007 ZXing authors
 *
 * 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.
 */

namespace com.google.zxing.common
{

	/// <summary>
	/// <p>A simple, fast array of bits, represented compactly by an array of ints internally.</p>
	/// 
	/// @author Sean Owen
	/// </summary>
	public sealed class BitArray
	{

	  private int[] bits;
	  private int size;

	  public BitArray()
	  {
		this.size = 0;
		this.bits = new int[1];
	  }

	  public BitArray(int size)
	  {
		this.size = size;
		this.bits = makeArray(size);
	  }

	  public int Size
	  {
		  get
		  {
			return size;
		  }
	  }

	  public int SizeInBytes
	  {
		  get
		  {
			return (size + 7) >> 3;
		  }
	  }

	  private void ensureCapacity(int size)
	  {
		if (size > bits.Length << 5)
		{
		  int[] newBits = makeArray(size);
		  Array.Copy(bits, 0, newBits, 0, bits.Length);
		  this.bits = newBits;
		}
	  }

	  /// <param name="i"> bit to get </param>
	  /// <returns> true iff bit i is set </returns>
	  public bool get(int i)
	  {
		return (bits[i >> 5] & (1 << (i & 0x1F))) != 0;
	  }

	  /// <summary>
	  /// Sets bit i.
	  /// </summary>
	  /// <param name="i"> bit to set </param>
	  public void set(int i)
	  {
		bits[i >> 5] |= 1 << (i & 0x1F);
	  }

	  /// <summary>
	  /// Flips bit i.
	  /// </summary>
	  /// <param name="i"> bit to set </param>
	  public void flip(int i)
	  {
		bits[i >> 5] ^= 1 << (i & 0x1F);
	  }

	  /// <param name="from"> first bit to check </param>
	  /// <returns> index of first bit that is set, starting from the given index, or size if none are set
	  ///  at or beyond this given index </returns>
	  /// <seealso cref= #getNextUnset(int) </seealso>
	  public int getNextSet(int from)
	  {
		if (from >= size)
		{
		  return size;
		}
		int bitsOffset = from >> 5;
		int currentBits = bits[bitsOffset];
		// mask off lesser bits first
		currentBits &= ~((1 << (from & 0x1F)) - 1);
		while (currentBits == 0)
		{
		  if (++bitsOffset == bits.Length)
		  {
			return size;
		  }
		  currentBits = bits[bitsOffset];
		}
        //int result = (bitsOffset << 5) + int.numberOfTrailingZeros(currentBits);
		int result = (bitsOffset << 5) + currentBits.NumberOfTrailingZeros();
	return result > size ? size : result;
	  }

	  /// <seealso cref= #getNextSet(int) </seealso>
	  public int getNextUnset(int from)
	  {
		if (from >= size)
		{
		  return size;
		}
		int bitsOffset = from >> 5;
		int currentBits = ~bits[bitsOffset];
		// mask off lesser bits first
		currentBits &= ~((1 << (from & 0x1F)) - 1);
		while (currentBits == 0)
		{
		  if (++bitsOffset == bits.Length)
		  {
			return size;
		  }
		  currentBits = ~bits[bitsOffset];
		}
        //int result = (bitsOffset << 5) + int.numberOfTrailingZeros(currentBits);
		int result = (bitsOffset << 5) + currentBits.NumberOfTrailingZeros();
		return result > size ? size : result;
	  }

	  /// <summary>
	  /// Sets a block of 32 bits, starting at bit i.
	  /// </summary>
	  /// <param name="i"> first bit to set </param>
	  /// <param name="newBits"> the new value of the next 32 bits. Note again that the least-significant bit
	  /// corresponds to bit i, the next-least-significant to i+1, and so on. </param>
	  public void setBulk(int i, int newBits)
	  {
		bits[i >> 5] = newBits;
	  }

	  /// <summary>
	  /// Sets a range of bits.
	  /// </summary>
	  /// <param name="start"> start of range, inclusive. </param>
	  /// <param name="end"> end of range, exclusive </param>
	  public void setRange(int start, int end)
	  {
		if (end < start)
		{
		  throw new System.ArgumentException();
		}
		if (end == start)
		{
		  return;
		}
		end--; // will be easier to treat this as the last actually set bit -- inclusive
		int firstInt = start >> 5;
		int lastInt = end >> 5;
		for (int i = firstInt; i <= lastInt; i++)
		{
		  int firstBit = i > firstInt ? 0 : start & 0x1F;
		  int lastBit = i < lastInt ? 31 : end & 0x1F;
		  int mask;
		  if (firstBit == 0 && lastBit == 31)
		  {
			mask = -1;
		  }
		  else
		  {
			mask = 0;
			for (int j = firstBit; j <= lastBit; j++)
			{
			  mask |= 1 << j;
			}
		  }
		  bits[i] |= mask;
		}
	  }

	  /// <summary>
	  /// Clears all bits (sets to false).
	  /// </summary>
	  public void clear()
	  {
		int max = bits.Length;
		for (int i = 0; i < max; i++)
		{
		  bits[i] = 0;
		}
	  }

	  /// <summary>
	  /// Efficient method to check if a range of bits is set, or not set.
	  /// </summary>
	  /// <param name="start"> start of range, inclusive. </param>
	  /// <param name="end"> end of range, exclusive </param>
	  /// <param name="value"> if true, checks that bits in range are set, otherwise checks that they are not set </param>
	  /// <returns> true iff all bits are set or not set in range, according to value argument </returns>
	  /// <exception cref="IllegalArgumentException"> if end is less than or equal to start </exception>
	  public bool isRange(int start, int end, bool value)
	  {
		if (end < start)
		{
		  throw new System.ArgumentException();
		}
		if (end == start)
		{
		  return true; // empty range matches
		}
		end--; // will be easier to treat this as the last actually set bit -- inclusive
		int firstInt = start >> 5;
		int lastInt = end >> 5;
		for (int i = firstInt; i <= lastInt; i++)
		{
		  int firstBit = i > firstInt ? 0 : start & 0x1F;
		  int lastBit = i < lastInt ? 31 : end & 0x1F;
		  int mask;
		  if (firstBit == 0 && lastBit == 31)
		  {
			mask = -1;
		  }
		  else
		  {
			mask = 0;
			for (int j = firstBit; j <= lastBit; j++)
			{
			  mask |= 1 << j;
			}
		  }

		  // Return false if we're looking for 1s and the masked bits[i] isn't all 1s (that is,
		  // equals the mask, or we're looking for 0s and the masked portion is not all 0s
		  if ((bits[i] & mask) != (value ? mask : 0))
		  {
			return false;
		  }
		}
		return true;
	  }

	  public void appendBit(bool bit)
	  {
		ensureCapacity(size + 1);
		if (bit)
		{
		  bits[size >> 5] |= 1 << (size & 0x1F);
		}
		size++;
	  }

	  /// <summary>
	  /// Appends the least-significant bits, from value, in order from most-significant to
	  /// least-significant. For example, appending 6 bits from 0x000001E will append the bits
	  /// 0, 1, 1, 1, 1, 0 in that order.
	  /// </summary>
	  public void appendBits(int value, int numBits)
	  {
		if (numBits < 0 || numBits > 32)
		{
		  throw new System.ArgumentException("Num bits must be between 0 and 32");
		}
		ensureCapacity(size + numBits);
		for (int numBitsLeft = numBits; numBitsLeft > 0; numBitsLeft--)
		{
		  appendBit(((value >> (numBitsLeft - 1)) & 0x01) == 1);
		}
	  }

	  public void appendBitArray(BitArray other)
	  {
		int otherSize = other.size;
		ensureCapacity(size + otherSize);
		for (int i = 0; i < otherSize; i++)
		{
		  appendBit(other.get(i));
		}
	  }

	  public void xor(BitArray other)
	  {
		if (bits.Length != other.bits.Length)
		{
		  throw new System.ArgumentException("Sizes don't match");
		}
		for (int i = 0; i < bits.Length; i++)
		{
		  // The last byte could be incomplete (i.e. not have 8 bits in
		  // it) but there is no problem since 0 XOR 0 == 0.
		  bits[i] ^= other.bits[i];
		}
	  }

	  /// 
	  /// <param name="bitOffset"> first bit to start writing </param>
	  /// <param name="array"> array to write into. Bytes are written most-significant byte first. This is the opposite
	  ///  of the internal representation, which is exposed by <seealso cref="#getBitArray()"/> </param>
	  /// <param name="offset"> position in array to start writing </param>
	  /// <param name="numBytes"> how many bytes to write </param>
	  public void toBytes(int bitOffset, sbyte[] array, int offset, int numBytes)
	  {
		for (int i = 0; i < numBytes; i++)
		{
		  int theByte = 0;
		  for (int j = 0; j < 8; j++)
		  {
			if (get(bitOffset))
			{
			  theByte |= 1 << (7 - j);
			}
			bitOffset++;
		  }
		  array[offset + i] = (sbyte) theByte;
		}
	  }

	  /// <returns> underlying array of ints. The first element holds the first 32 bits, and the least
	  ///         significant bit is bit 0. </returns>
	  public int[] BitArrayBits
	  {
		  get
		  {
			return bits;
		  }
	  }

	  /// <summary>
	  /// Reverses all bits in the array.
	  /// </summary>
	  public void reverse()
	  {
		int[] newBits = new int[bits.Length];
		int size = this.size;
		for (int i = 0; i < size; i++)
		{
		  if (get(size - i - 1))
		  {
			newBits[i >> 5] |= 1 << (i & 0x1F);
		  }
		}
		bits = newBits;
	  }

	  private static int[] makeArray(int size)
	  {
		return new int[(size + 31) >> 5];
	  }

	  public override string ToString()
	  {
		StringBuilder result = new StringBuilder(size);
		for (int i = 0; i < size; i++)
		{
		  if ((i & 0x07) == 0)
		  {
			result.Append(' ');
		  }
		  result.Append(get(i) ? 'X' : '.');
		}
		return result.ToString();
	  }

	}
}