Method decode4to3

samples/JGroups/src/S3_PING.java:2221–2277

Decodes four bytes from array source and writes the resulting bytes (up to three of them) to destination . The source and destination arrays can be manipulated anywhere along their length by specifying srcOffset and destOffset . This method does not check to

(byte[] source, int srcOffset, byte[] destination, int destOffset)

         * @since 1.3
         */
        private static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset) {
            // 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 {
                try {
                    // 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;
                }
                catch(Exception e) {
                    System.out.println(valueOf(source[srcOffset]) + ": " + (DECODABET[source[srcOffset]]));
                    System.out.println(valueOf(source[srcOffset + 1]) + ": " + (DECODABET[source[srcOffset + 1]]));
                    System.out.println(valueOf(source[srcOffset + 2]) + ": " + (DECODABET[source[srcOffset + 2]]));
                    System.out.println(String.valueOf(source[srcOffset + 3]) + ": " + (DECODABET[source[srcOffset + 3]]));
                    return -1;
                }   //e nd catch
            }
        }   // end decodeToBytes