content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * based on code by MyCATCopyrightHolder Copyright (c) 2013, OpenCloudDB/MyCAT.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  package com.actiontech.dble.backend.mysql;
  
  import java.nio.ByteBuffer;
  
  /**
   * @author mycat
   */
  public final class ByteUtil {
      private ByteUtil() {
      }
  
      public static int readUB2(byte[] data, int offset) {
          int i = data[offset] & 0xff;
          i |= (data[++offset] & 0xff) << 8;
          return i;
      }
  
      public static int readUB3(byte[] data, int offset) {
          int i = data[offset] & 0xff;
          i |= (data[++offset] & 0xff) << 8;
          i |= (data[++offset] & 0xff) << 16;
          return i;
      }
  
      public static long readUB4(byte[] data, int offset) {
          long l = data[offset] & 0xff;
          l |= (data[++offset] & 0xff) << 8;
          l |= (data[++offset] & 0xff) << 16;
          l |= ((long) (data[++offset] & 0xff)) << 24;
          return l;
      }
  
      public static long readLong(byte[] data, int offset) {
          long l = (long) (data[offset] & 0xff);
          l |= (long) (data[++offset] & 0xff) << 8;
          l |= (long) (data[++offset] & 0xff) << 16;
          l |= (long) (data[++offset] & 0xff) << 24;
          l |= (long) (data[++offset] & 0xff) << 32;
          l |= (long) (data[++offset] & 0xff) << 40;
          l |= (long) (data[++offset] & 0xff) << 48;
          l |= (long) (data[++offset] & 0xff) << 56;
          return l;
      }
  
      public static long readLength(byte[] data, int offset) {
          int length = data[offset++] & 0xff;
          switch (length) {
              case 251:
                  return MySQLMessage.NULL_LENGTH;
              case 252:
                  return readUB2(data, offset);
              case 253:
                  return readUB3(data, offset);
              case 254:
                  return readLong(data, offset);
              default:
                  return length;
          }
      }
  
      public static int lengthToZero(byte[] data, int offset) {
          int start = offset;
          for (int i = start; i < data.length; i++) {
              if (data[i] == 0) {
                  return (i - start);
              }
          }
          int remaining = data.length - start;
          return remaining > 0 ? remaining : 0;
      }
  
      public static int decodeLength(byte[] src) {
          int length = src.length;
          if (length < 251) {
              return 1 + length;
          } else if (length < 0x10000L) {
              return 3 + length;
          } else if (length < 0x1000000L) {
              return 4 + length;
          } else {
              return 9 + length;
          }
      }
  
      public static int decodeLength(long length) {
          if (length < 251) {
              return 1;
          } else if (length < 0x10000L) {
              return 3;
          } else if (length < 0x1000000L) {
              return 4;
          } else {
              return 9;
          }
      }
  
      public static void writeUB3(byte[] packet, int val, int offset) {
          packet[offset] = (byte) (val & 0xff);
          packet[offset + 1] = (byte) (val >>> 8);
          packet[offset + 2] = (byte) (val >>> 16);
      }
  
      public static void writeUB3(ByteBuffer buffer, int val, int offset) {
          buffer.put(offset, (byte) (val & 0xff));
          buffer.put(offset + 1, (byte) (val >>> 8));
          buffer.put(offset + 2, (byte) (val >>> 16));
      }
  
      public static void writeUB3(byte[] packet, int length) {
          writeUB3(packet, length, 0);
      }
  
      public static void writeUB4(byte[] packet, long l, int offset) {
          packet[offset] = (byte) (l & 0xff);
          packet[offset + 1] = (byte) (l >>> 8);
          packet[offset + 2] = (byte) (l >>> 16);
          packet[offset + 3] = (byte) (l >>> 24);
      }
  
  }
  