/**
* constructs a frequency table from an array of bytes
*
* @param source the array to construct the table from
*/
public static int[] constructTable(byte[] source) {
int[] ret = new int[TABLESIZE];
for (int i = 0; i < source.length; i++) {
ret[IntTool.ByteToInt(source[i])]++;
}
return ret;
}
/**
* Expand a rll-compressed array
*
* @param source the compressed array. First byte must be the rllchar.
* @return a newly created array with the expanded data.
*/
public static byte[] expand(byte[] source) {
ByteArrayOutputStream baos = new ByteArrayOutputStream(source.length);
byte rllchar = source[0];
int i;
for (i = 1; i < source.length - 2; i++) {
if (source[i] == rllchar) {
if (source[i + 1] == 1) {
baos.write(rllchar);
i++;
} else {
int k = IntTool.ByteToInt(source[i + 1]);
while (k-- > 0) {
baos.write(source[i + 2]);
}
i += 2;
}
} else {
baos.write(source[i]);
}
}
while (i < source.length) {
baos.write(source[i++]);
}
return baos.toByteArray();
}