content: /*
   * 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.
   */
  
  package com.ailiwean.core.zxing.core.common;
  
  import java.util.Arrays;
  
  /**
   * <p>A simple, fast array of bits, represented compactly by an array of ints internally.</p>
   *
   * @author Sean Owen
   */
  public final class BitArray implements Cloneable {
  
    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);
    }
  
    // For testing only
    BitArray(int[] bits, int size) {
      this.bits = bits;
      this.size = size;
    }
  
    public int getSize() {
      return size;
    }
  
    public int getSizeInBytes() {
      return (size + 7) / 8;
    }
  
    private void ensureCapacity(int size) {
      if (size > bits.length * 32) {
        int[] newBits = makeArray(size);
        System.arraycopy(bits, 0, newBits, 0, bits.length);
        this.bits = newBits;
      }
    }
  
    /**
     * @param i bit to get
     * @return true iff bit i is set
     */
    public boolean get(int i) {
      return (bits[i / 32] & (1 << (i & 0x1F))) != 0;
    }
  
    /**
     * Sets bit i.
     *
     * @param i bit to set
     */
    public void set(int i) {
      bits[i / 32] |= 1 << (i & 0x1F);
    }
  
    /**
     * Flips bit i.
     *
     * @param i bit to set
     */
    public void flip(int i) {
      bits[i / 32] ^= 1 << (i & 0x1F);
    }
  
    /**
     * @param from first bit to check
     * @return index of first bit that is set, starting from the given index, or size if none are set
     *  at or beyond this given index
     * @see #getNextUnset(int)
     */
    public int getNextSet(int from) {
      if (from >= size) {
        return size;
      }
      int bitsOffset = from / 32;
      int currentBits = bits[bitsOffset];
      // mask off lesser bits first
      currentBits &= -(1 << (from & 0x1F));
      while (currentBits == 0) {
        if (++bitsOffset == bits.length) {
          return size;
        }
        currentBits = bits[bitsOffset];
      }
      int result = (bitsOffset * 32) + Integer.numberOfTrailingZeros(currentBits);
      return Math.min(result, size);
    }
  
    /**
     * @param from index to start looking for unset bit
     * @return index of next unset bit, or {@code size} if none are unset until the end
     * @see #getNextSet(int)
     */
    public int getNextUnset(int from) {
      if (from >= size) {
        return size;
      }
      int bitsOffset = from / 32;
      int currentBits = ~bits[bitsOffset];
      // mask off lesser bits first
      currentBits &= -(1 << (from & 0x1F));
      while (currentBits == 0) {
        if (++bitsOffset == bits.length) {
          return size;
        }
        currentBits = ~bits[bitsOffset];
      }
      int result = (bitsOffset * 32) + Integer.numberOfTrailingZeros(currentBits);
      return Math.min(result, size);
    }
  
    /**
     * Sets a block of 32 bits, starting at bit i.
     *
     * @param i first bit to set
     * @param 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.
     */
    public void setBulk(int i, int newBits) {
      bits[i / 32] = newBits;
    }
  
    /**
     * Sets a range of bits.
     *
     * @param start start of range, inclusive.
     * @param end end of range, exclusive
     */
    public void setRange(int start, int end) {
      if (end < start || start < 0 || end > size) {
        throw new IllegalArgumentException();
      }
      if (end == start) {
        return;
      }
      end--; // will be easier to treat this as the last actually set bit -- inclusive
      int firstInt = start / 32;
      int lastInt = end / 32;
      for (int i = firstInt; i <= lastInt; i++) {
        int firstBit = i > firstInt ? 0 : start & 0x1F;
        int lastBit = i < lastInt ? 31 : end & 0x1F;
        // Ones from firstBit to lastBit, inclusive
        int mask = (2 << lastBit) - (1 << firstBit);
        bits[i] |= mask;
      }
    }
  
    /**
     * Clears all bits (sets to false).
     */
    public void clear() {
      int max = bits.length;
      for (int i = 0; i < max; i++) {
        bits[i] = 0;
      }
    }
  
    /**
     * Efficient method to check if a range of bits is set, or not set.
     *
     * @param start start of range, inclusive.
     * @param end end of range, exclusive
     * @param value if true, checks that bits in range are set, otherwise checks that they are not set
     * @return true iff all bits are set or not set in range, according to value argument
     * @throws IllegalArgumentException if end is less than start or the range is not contained in the array
     */
    public boolean isRange(int start, int end, boolean value) {
      if (end < start || start < 0 || end > size) {
        throw new IllegalArgumentException();
      }
      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 / 32;
      int lastInt = end / 32;
      for (int i = firstInt; i <= lastInt; i++) {
        int firstBit = i > firstInt ? 0 : start & 0x1F;
        int lastBit = i < lastInt ? 31 : end & 0x1F;
        // Ones from firstBit to lastBit, inclusive
        int mask = (2 << lastBit) - (1 << firstBit);
  
        // 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(boolean bit) {
      ensureCapacity(size + 1);
      if (bit) {
        bits[size / 32] |= 1 << (size & 0x1F);
      }
      size++;
    }
  
    /**
     * 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.
     *
     * @param value {@code int} containing bits to append
     * @param numBits bits from value to append
     */
    public void appendBits(int value, int numBits) {
      if (numBits < 0 || numBits > 32) {
        throw new IllegalArgumentException("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 (size != other.size) {
        throw new IllegalArgumentException("Sizes don't match");
      }
      for (int i = 0; i < bits.length; i++) {
        // The last int could be incomplete (i.e. not have 32 bits in
        // it) but there is no problem since 0 XOR 0 == 0.
        bits[i] ^= other.bits[i];
      }
    }
  
    /**
     *
     * @param bitOffset first bit to start writing
     * @param array array to write into. Bytes are written most-significant byte first. This is the opposite
     *  of the internal representation, which is exposed by {@link #getBitArray()}
     * @param offset position in array to start writing
     * @param numBytes how many bytes to write
     */
    public void toBytes(int bitOffset, byte[] 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] = (byte) theByte;
      }
    }
  
    /**
     * @return underlying array of ints. The first element holds the first 32 bits, and the least
     *         significant bit is bit 0.
     */
    public int[] getBitArray() {
      return bits;
    }
  
    /**
     * Reverses all bits in the array.
     */
    public void reverse() {
      int[] newBits = new int[bits.length];
      // reverse all int's first
      int len = (size - 1) / 32;
      int oldBitsLen = len + 1;
      for (int i = 0; i < oldBitsLen; i++) {
        long x = bits[i];
        x = ((x >>  1) & 0x55555555L) | ((x & 0x55555555L) <<  1);
        x = ((x >>  2) & 0x33333333L) | ((x & 0x33333333L) <<  2);
        x = ((x >>  4) & 0x0f0f0f0fL) | ((x & 0x0f0f0f0fL) <<  4);
        x = ((x >>  8) & 0x00ff00ffL) | ((x & 0x00ff00ffL) <<  8);
        x = ((x >> 16) & 0x0000ffffL) | ((x & 0x0000ffffL) << 16);
        newBits[len - i] = (int) x;
      }
      // now correct the int's if the bit size isn't a multiple of 32
      if (size != oldBitsLen * 32) {
        int leftOffset = oldBitsLen * 32 - size;
        int currentInt = newBits[0] >>> leftOffset;
        for (int i = 1; i < oldBitsLen; i++) {
          int nextInt = newBits[i];
          currentInt |= nextInt << (32 - leftOffset);
          newBits[i - 1] = currentInt;
          currentInt = nextInt >>> leftOffset;
        }
        newBits[oldBitsLen - 1] = currentInt;
      }
      bits = newBits;
    }
  
    private static int[] makeArray(int size) {
      return new int[(size + 31) / 32];
    }
  
    @Override
    public boolean equals(Object o) {
      if (!(o instanceof BitArray)) {
        return false;
      }
      BitArray other = (BitArray) o;
      return size == other.size && Arrays.equals(bits, other.bits);
    }
  
    @Override
    public int hashCode() {
      return 31 * size + Arrays.hashCode(bits);
    }
  
    @Override
    public String toString() {
      StringBuilder result = new StringBuilder(size + (size / 8) + 1);
      for (int i = 0; i < size; i++) {
        if ((i & 0x07) == 0) {
          result.append(' ');
        }
        result.append(get(i) ? 'X' : '.');
      }
      return result.toString();
    }
  
    @Override
    public BitArray clone() {
      return new BitArray(bits.clone(), size);
    }
  
  }
  