private static int decode4to3()

in core/src/main/java/org/apache/calcite/avatica/util/Base64.java [1057:1128]
45 lines of code
7 McCabe index (conditional complexity)

  private static int decode4to3(
      byte[] source, int srcOffset,
      byte[] destination, int destOffset, int options ) {

    // Lots of error checking and exception throwing
    if( source == null ){
      throw new NullPointerException( "Source array was null." );
    }   // end if
    if( destination == null ){
      throw new NullPointerException( "Destination array was null." );
    }   // end if
    if( srcOffset < 0 || srcOffset + 3 >= source.length ){
      throw new IllegalArgumentException( String.format( Locale.ROOT,
          "Source array with length %d cannot have offset of %d and still process four bytes.",
          source.length, srcOffset ) );
    }   // end if
    if( destOffset < 0 || destOffset +2 >= destination.length ){
      throw new IllegalArgumentException( String.format( Locale.ROOT,
          "Destination array with length %d cannot have offset of %d and still store three bytes.",
          destination.length, destOffset ) );
    }   // end if


    byte[] DECODABET = getDecodabet( options );

    // Example: Dk==
    if( source[ srcOffset + 2] == EQUALS_SIGN ) {
      // Two ways to do the same thing. Don't know which way I like best.
      //int outBuff =   ( ( DECODABET[ source[ srcOffset    ] ] << 24 ) >>>  6 )
      //              | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
      int outBuff =   ( ( DECODABET[ source[ srcOffset    ] ] & 0xFF ) << 18 )
          | ( ( DECODABET[ source[ srcOffset + 1] ] & 0xFF ) << 12 );

      destination[ destOffset ] = (byte)( outBuff >>> 16 );
      return 1;
    }

    // Example: DkL=
    else if( source[ srcOffset + 3 ] == EQUALS_SIGN ) {
      // Two ways to do the same thing. Don't know which way I like best.
      //int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] << 24 ) >>>  6 )
      //              | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
      //              | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
      int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] & 0xFF ) << 18 )
          | ( ( DECODABET[ source[ srcOffset + 1 ] ] & 0xFF ) << 12 )
          | ( ( DECODABET[ source[ srcOffset + 2 ] ] & 0xFF ) <<  6 );

      destination[ destOffset     ] = (byte)( outBuff >>> 16 );
      destination[ destOffset + 1 ] = (byte)( outBuff >>>  8 );
      return 2;
    }

    // Example: DkLE
    else {
      // Two ways to do the same thing. Don't know which way I like best.
      //int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] << 24 ) >>>  6 )
      //              | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
      //              | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
      //              | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
      int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] & 0xFF ) << 18 )
          | ( ( DECODABET[ source[ srcOffset + 1 ] ] & 0xFF ) << 12 )
          | ( ( DECODABET[ source[ srcOffset + 2 ] ] & 0xFF ) <<  6)
          | ( ( DECODABET[ source[ srcOffset + 3 ] ] & 0xFF )      );


      destination[ destOffset     ] = (byte)( outBuff >> 16 );
      destination[ destOffset + 1 ] = (byte)( outBuff >>  8 );
      destination[ destOffset + 2 ] = (byte)( outBuff       );

      return 3;
    }
  }   // end decodeToBytes