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To Pack 8bit To 7bit Hex
// description of your code here
public static byte[] getSeptets(byte[] octetBytes, boolean hasUDH) throws IOException {
byte[] compressedData = null;
try {
ByteArrayOutputStream bas = new ByteArrayOutputStream();
int userDataHeaderLen = 0;
int padBits = 0;
int userDataLen = octetBytes.length;
if (hasUDH) {
userDataHeaderLen = (octetBytes[0] & 0xFF) + 1; // plus 1 za
// prvi byte
// duzine
bas.write(octetBytes, 0, userDataHeaderLen);
userDataLen = octetBytes.length - userDataHeaderLen;
padBits = (userDataHeaderLen * 8) % 7;
if (padBits != 0)
padBits = 7 - padBits;
}
byte pack[] = pack(octetBytes, userDataHeaderLen, userDataLen, padBits);
bas.write(pack, 0, pack.length);
compressedData = bas.toByteArray();
} catch (Throwable e) {
throw new IOException("Exception in (8bit to 7bit Hex conversion)", e);
}
return compressedData;
}
public static byte[] pack(byte[] ba) {
return pack(ba, 0, ba.length, 0);
}
public static byte[] pack(byte[] ba, int off, int len, int pad) {
String m1 = "", m2 = "";
for (int i = 0; i < pad; i++)
m1 += "0";
for (int i = off; i < off + len; i++)
m1 = zeroPad(Integer.toBinaryString(ba[i] & 0x7F), 7) + m1;
if (m1.length() % 8 != 0)
m1 = zeroPad(m1, m1.length() + (8 - m1.length() % 8));
for (int i = 0; i < m1.length(); i += 8) {
int b = Integer.parseInt(m1.substring(i, i + 8), 2);
m2 = zeroPad(Integer.toHexString(b).toUpperCase(), 2) + m2;
}
return fromHexString(m2);
}
public static byte[] unpack(byte[] ba, int unpack_len) {
return unpack(ba, 0, ba.length, 0, unpack_len);
}
public static byte[] unpack(byte[] ba, int off, int len, int pad, int unpack_len) {
String m1 = "", m2 = "";
for (int i = off; i < off + len; i++) {
m1 = zeroPad(Integer.toBinaryString(ba[i] & 0xFF), 8) + m1;
}
m1 = m1.substring(0, m1.length() - pad);
m1 = m1.substring(m1.length() % 7);
for (int i = 0; i < m1.length(); i += 7) {
int b = Integer.parseInt(m1.substring(i, i + 7), 2);
m2 = zeroPad(Integer.toHexString(b).toUpperCase(), 2) + m2;
}
m2 = m2.substring(0, unpack_len * 2);
return fromHexString(m2);
}
private static String zeroPad(String s, int p) {
while (s.length() < p)
s = "0" + s;
return s;
}
Comments
Mlungisi Sincuba replied on Fri, 2011/12/02 - 4:31am
Mlungisi Sincuba replied on Fri, 2011/12/02 - 4:31am