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package io.polaris.core.codec;
import java.io.IOException;
import java.io.OutputStream;
/**
* @author Qt
* @since 1.8
*/
public class HexEncoder implements Encoder {
protected final byte[] encodingTable =
{
(byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7',
(byte) '8', (byte) '9', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f'
};
/*
* set up the decoding table.
*/
protected final byte[] decodingTable = new byte[128];
protected void initialiseDecodingTable() {
for (int i = 0; i < decodingTable.length; i++) {
decodingTable[i] = (byte) 0xff;
}
for (int i = 0; i < encodingTable.length; i++) {
decodingTable[encodingTable[i]] = (byte) i;
}
decodingTable['A'] = decodingTable['a'];
decodingTable['B'] = decodingTable['b'];
decodingTable['C'] = decodingTable['c'];
decodingTable['D'] = decodingTable['d'];
decodingTable['E'] = decodingTable['e'];
decodingTable['F'] = decodingTable['f'];
}
public HexEncoder() {
initialiseDecodingTable();
}
public int encode(byte[] inBuf, int inOff, int inLen, byte[] outBuf, int outOff) throws IOException {
int inPos = inOff;
int inEnd = inOff + inLen;
int outPos = outOff;
while (inPos < inEnd) {
int b = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[b >>> 4];
outBuf[outPos++] = encodingTable[b & 0xF];
}
return outPos - outOff;
}
@Override
public int getEncodedLength(int inputLength) {
return inputLength * 2;
}
@Override
public int getMaxDecodedLength(int inputLength) {
return inputLength / 2;
}
/**
* encode the input data producing a HexCodec output stream.
*
* @return the number of bytes produced.
*/
@Override
public int encode(byte[] buf, int off, int len, OutputStream out) throws IOException {
if (len < 0) {
return 0;
}
byte[] tmp = new byte[72];
int remaining = len;
while (remaining > 0) {
int inLen = Math.min(36, remaining);
int outLen = encode(buf, off, inLen, tmp, 0);
out.write(tmp, 0, outLen);
off += inLen;
remaining -= inLen;
}
return len * 2;
}
private static boolean ignore(char c) {
return c == '\n' || c == '\r' || c == '\t' || c == ' ';
}
/**
* decode the HexCodec encoded byte data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
@Override
public int decode(byte[] data, int off, int length, OutputStream out) throws IOException {
byte b1, b2;
int outLen = 0;
byte[] buf = new byte[36];
int bufOff = 0;
int end = off + length;
while (end > off) {
if (!ignore((char) data[end - 1])) {
break;
}
end--;
}
int i = off;
while (i < end) {
while (i < end && ignore((char) data[i])) {
i++;
}
b1 = decodingTable[data[i++]];
while (i < end && ignore((char) data[i])) {
i++;
}
b2 = decodingTable[data[i++]];
if ((b1 | b2) < 0) {
throw new IOException("invalid characters encountered in HexCodec data");
}
buf[bufOff++] = (byte) ((b1 << 4) | b2);
if (bufOff == buf.length) {
out.write(buf);
bufOff = 0;
}
outLen++;
}
if (bufOff > 0) {
out.write(buf, 0, bufOff);
}
return outLen;
}
/**
* decode the HexCodec encoded String data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
@Override
public int decode(String data, OutputStream out) throws IOException {
byte b1, b2;
int length = 0;
byte[] buf = new byte[36];
int bufOff = 0;
int end = data.length();
while (end > 0) {
if (!ignore(data.charAt(end - 1))) {
break;
}
end--;
}
int i = 0;
while (i < end) {
while (i < end && ignore(data.charAt(i))) {
i++;
}
b1 = decodingTable[data.charAt(i++)];
while (i < end && ignore(data.charAt(i))) {
i++;
}
b2 = decodingTable[data.charAt(i++)];
if ((b1 | b2) < 0) {
throw new IOException("invalid characters encountered in HexCodec string");
}
buf[bufOff++] = (byte) ((b1 << 4) | b2);
if (bufOff == buf.length) {
out.write(buf);
bufOff = 0;
}
length++;
}
if (bufOff > 0) {
out.write(buf, 0, bufOff);
}
return length;
}
byte[] decodeStrict(String str, int off, int len) throws IOException {
if (null == str) {
throw new NullPointerException("'str' cannot be null");
}
if (off < 0 || len < 0 || off > (str.length() - len)) {
throw new IndexOutOfBoundsException("invalid offset and/or length specified");
}
if (0 != (len & 1)) {
throw new IOException("a hexadecimal encoding must have an even number of characters");
}
int resultLen = len >>> 1;
byte[] result = new byte[resultLen];
int strPos = off;
for (int i = 0; i < resultLen; ++i) {
byte b1 = decodingTable[str.charAt(strPos++)];
byte b2 = decodingTable[str.charAt(strPos++)];
int n = (b1 << 4) | b2;
if (n < 0) {
throw new IOException("invalid characters encountered in HexCodec string");
}
result[i] = (byte) n;
}
return result;
}
}
