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Dahua ICC Open API SDK for Java
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package com.dahuatech.hutool.core.codec;

/**
 * BCD码（Binary-Coded Decimal‎）亦称二进码十进数或二-十进制代码

 * BCD码这种编码形式利用了四个位元来储存一个十进制的数码，使二进制和十进制之间的转换得以快捷的进行

 * see http://cuisuqiang.iteye.com/blog/1429956
 *
 * @author Looly
 */
public class BCD {

  /**
   * 字符串转BCD码
   *
   * @param asc ASCII字符串
   * @return BCD
   */
  public static byte[] strToBcd(String asc) {
    int len = asc.length();
    int mod = len % 2;
    if (mod != 0) {
      asc = "0" + asc;
      len = asc.length();
    }
    byte[] abt;
    if (len >= 2) {
      len >>= 1;
    }
    byte[] bbt;
    bbt = new byte[len];
    abt = asc.getBytes();
    int j;
    int k;
    for (int p = 0; p < asc.length() / 2; p++) {
      if ((abt[2 * p] >= '0') && (abt[2 * p] <= '9')) {
        j = abt[2 * p] - '0';
      } else if ((abt[2 * p] >= 'a') && (abt[2 * p] <= 'z')) {
        j = abt[2 * p] - 'a' + 0x0a;
      } else {
        j = abt[2 * p] - 'A' + 0x0a;
      }
      if ((abt[2 * p + 1] >= '0') && (abt[2 * p + 1] <= '9')) {
        k = abt[2 * p + 1] - '0';
      } else if ((abt[2 * p + 1] >= 'a') && (abt[2 * p + 1] <= 'z')) {
        k = abt[2 * p + 1] - 'a' + 0x0a;
      } else {
        k = abt[2 * p + 1] - 'A' + 0x0a;
      }
      int a = (j << 4) + k;
      byte b = (byte) a;
      bbt[p] = b;
    }
    return bbt;
  }

  /**
   * ASCII转BCD
   *
   * @param ascii ASCII byte数组
   * @return BCD
   */
  public static byte[] ascToBcd(byte[] ascii) {
    return ascToBcd(ascii, ascii.length);
  }

  /**
   * ASCII转BCD
   *
   * @param ascii ASCII byte数组
   * @param ascLength 长度
   * @return BCD
   */
  public static byte[] ascToBcd(byte[] ascii, int ascLength) {
    byte[] bcd = new byte[ascLength / 2];
    int j = 0;
    for (int i = 0; i < (ascLength + 1) / 2; i++) {
      bcd[i] = ascToBcd(ascii[j++]);
      bcd[i] = (byte) (((j >= ascLength) ? 0x00 : ascToBcd(ascii[j++])) + (bcd[i] << 4));
    }
    return bcd;
  }

  /**
   * BCD转ASCII字符串
   *
   * @param bytes BCD byte数组
   * @return ASCII字符串
   */
  public static String bcdToStr(byte[] bytes) {
    char[] temp = new char[bytes.length * 2];
    char val;

    for (int i = 0; i < bytes.length; i++) {
      val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
      temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

      val = (char) (bytes[i] & 0x0f);
      temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
    }
    return new String(temp);
  }

  // ----------------------------------------------------------------- Private method start
  /**
   * 转换单个byte为BCD
   *
   * @param asc ACSII
   * @return BCD
   */
  private static byte ascToBcd(byte asc) {
    byte bcd;

    if ((asc >= '0') && (asc <= '9')) {
      bcd = (byte) (asc - '0');
    } else if ((asc >= 'A') && (asc <= 'F')) {
      bcd = (byte) (asc - 'A' + 10);
    } else if ((asc >= 'a') && (asc <= 'f')) {
      bcd = (byte) (asc - 'a' + 10);
    } else {
      bcd = (byte) (asc - 48);
    }
    return bcd;
  }
  // ----------------------------------------------------------------- Private method end
}