private static int new_bits(int maxpower, ref dec_data data)
{
int bits = 0;
int power = 1;
int resb = 0;
while (power != maxpower)
{
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0)
{
data.position = 32768;
data.val = NextValue(ref data);
}
bits |= (resb > 0 ? 1 : 0) * power;
power <<= 1;
}
return(bits);
}
private unsafe static string _decompress(int length, int resetValue, string input)
{
var powers = stackalloc int[32];
for (int i = 0; i < 32; i++)
{
powers[i] = (int)Math.Pow(2, i);
}
char[][] dictionary = new char[length * 4][];
char[][] result = new char[length * 4][];
int resultArraySize = 0;
int charstoreturn = 0;
int dictSize = 0;
int next;
int enlargeIn = 4;
int numBits = 3;
int c = 0;
var data = new dec_data()
{
position = resetValue, index = 0, input = input
};
data.val = NextValue(ref data);
EnsureSize(ref dictionary, dictSize + 4);
EnsureSize(ref result, resultArraySize + 2);
for (int i = 0; i < 3; i++)
{
dictionary[dictSize++] = new char[] { (char)i };
}
int bits = 0;
bits = new_bits(powers[2], ref data);
switch (next = bits)
{
case 0:
bits = new_bits(powers[8], ref data);
c = (char)(bits);
break;
case 1:
bits = new_bits(powers[16], ref data);
c = (char)(bits);
break;
case 2:
return("");
}
;
char[] w = new char[1] {
(char)c
};
//string w = new string(c, 1);
result[resultArraySize++] = w;
charstoreturn += w.Length;
dictionary[dictSize++] = w;
char[] entry;
while (true)
{
if (data.index > length)
{
return("");
}
bits = new_bits(powers[numBits], ref data);
c = bits;
switch (bits)
{
case 0:
bits = new_bits(powers[8], ref data);
dictionary[dictSize++] = new char[] { (char)(bits) };
c = (char)(dictSize - 1);
enlargeIn--;
break;
case 1:
bits = new_bits(powers[16], ref data);
dictionary[dictSize++] = new char[] { (char)(bits) };
c = (char)(dictSize - 1);
enlargeIn--;
break;
case 2:
StringBuilder ret = new StringBuilder(charstoreturn);
foreach (var str in result)
{
ret.Append(str);
}
return(ret.ToString());
}
if (enlargeIn == 0)
{
enlargeIn = powers[numBits];
numBits++;
}
char[] dictadd;
if (c < dictSize)
{
entry = dictionary[c];
dictadd = add(w, entry[0]);
}
else
{
if (c == dictSize)
{
entry = add(w, w[0]);
dictadd = entry;
}
else
{
return(null);
}
}
result[resultArraySize++] = entry;
charstoreturn += entry.Length;
// Add w+entry[0] to the dictionary.
dictionary[dictSize++] = dictadd;
w = entry;
enlargeIn--;
if (enlargeIn == 0)
{
enlargeIn = powers[numBits];
numBits++;
}
EnsureSize(ref dictionary, dictSize + 3);
EnsureSize(ref result, resultArraySize + 3);
}
}
private static int NextValue(ref dec_data data)
{
return(data.input[data.index++]);
}