/**
 *  Copyright 2010 Firat Salgur
 *  
 *  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.
 *  
 */
public class BCD {

    /**
     * long number to bcd byte array e.g. 123 --> (0000) 0001 0010 0011
     * e.g. 12 ---> 0001 0010
     */
    public static byte[] DecimalToBCD(long num) {
        int digits = 0;

        long temp = num;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }

        int byteLen = digits % 2 == 0 ? digits / 2 : (digits + 1) / 2;

        byte bcd[] = new byte[byteLen];

        for (int i = 0; i < digits; i++) {
            byte tmp = (byte) (num % 10);

            if (i % 2 == 0) {
                bcd[i / 2] = tmp;
            } else {
                bcd[i / 2] |= (byte) (tmp << 4);
            }

            num /= 10;
        }

        for (int i = 0; i < byteLen / 2; i++) {
            byte tmp = bcd[i];
            bcd[i] = bcd[byteLen - i - 1];
            bcd[byteLen - i - 1] = tmp;
        }

        return bcd;
    }

    public static long BCDToDecimal(byte[] bcd) {
        return Long.valueOf(BCD.BCDtoString(bcd));
    }
    
    public static String BCDtoString(byte bcd) {
        StringBuffer sb = new StringBuffer();
        
        byte high = (byte) (bcd & 0xf0);
        high >>>= (byte) 4;    
        high = (byte) (high & 0x0f);
        byte low = (byte) (bcd & 0x0f);
        
        sb.append(high);
        sb.append(low);
        
        return sb.toString();
    }
    
    public static String BCDtoString(byte[] bcd) {
        StringBuffer sb = new StringBuffer();
    
        for (int i = 0; i < bcd.length; i++) {
            sb.append(BCDtoString(bcd[i]));
        }
    
        return sb.toString();
    }
    
    public static void main(String[] args) {
        System.out.println("Testing DecimalToBCD:");
        BCD.testForValue(1L,        "00000001");
        BCD.testForValue(11L,       "00010001");
        BCD.testForValue(111L,      "0000000100010001");
        BCD.testForValue(1111L,     "0001000100010001");
        BCD.testForValue(11111L,    "000000010001000100010001");
        BCD.testForValue(42,        "01000010");
        BCD.testForValue(112233L,   "000100010010001000110011");
        BCD.testForValue(12345L,    "000000010010001101000101");
        
        System.out.println("\nTesting two way conversion using DecimalToBCD and back using BCDToDecimal:");
        BCD.testForValue(1L);
        BCD.testForValue(11L);
        BCD.testForValue(111L);
        BCD.testForValue(1111L);
        BCD.testForValue(11111L);
        BCD.testForValue(12983283L);
        BCD.testForValue(9832098349L);
    }
    
    private static void testForValue(long val, String expected) {
        String binaryString = BCD.byteArrayToBinaryString(BCD.DecimalToBCD(val));
        System.out.print(String.format("Testing: %10d -> %30s %4s\n", val, binaryString, binaryString.equals(expected) ? "[OK]" : "[FAIL]"));
    }
    
    private static void testForValue(long val) {
        long newVal = BCD.BCDToDecimal(BCD.DecimalToBCD(val));
        
        System.out.print(String.format("Testing: %10d -> %30d %4s\n", val, newVal, newVal == val ? "[OK]" : "[FAIL]"));
    }
    
    private static String byteArrayToBinaryString(byte[] bytes) {
        StringBuffer sb = new StringBuffer();
        for (byte i : bytes) {
            String byteInBinary = String.format("%8s", Integer.toBinaryString(i)).replace(' ', '0');
            sb.append(byteInBinary);
        }
        return sb.toString();
    }
}