internal static Buffer Compress(byte[] inputBytes, int offset, int length, Buffer buffer)
{
if (buffer == null)
{
buffer = new Buffer(32 + length * 6 / 5);
}
else
{
buffer.EnsureCapacity(32 + length * 6 / 5);
}
byte[] target = buffer.Data;
int targetIndex = 0;
int lasthit = offset;
int l = length;
while (l > 0)
{
if (l >= 128)
{
target[targetIndex++] = (byte)(0x80 | (l & 0x7f));
}
else
{
target[targetIndex++] = (byte)l;
}
l >>= 7;
}
int[] ilhm = Enumerable.Repeat(-1, length / 5).ToArray();
for (int i = offset; i + 4 < length && i < offset + 4; i++)
{
ilhm[ToInt(inputBytes, i) % ilhm.Length] = i;
}
for (int i = offset + 4; i < offset + length; i++)
{
Hit h = Search(inputBytes, i, length, ilhm);
if (i + 4 < offset + length)
{
ilhm[ToInt(inputBytes, i) % ilhm.Length] = i;
}
if (h != null)
{
if (lasthit < i)
{
int len = i - lasthit - 1;
if (len < 60)
{
target[targetIndex++] = (byte)(len << 2);
}
else if (len < 0x100)
{
target[targetIndex++] = 60 << 2;
target[targetIndex++] = (byte)len;
}
else if (len < 0x10000)
{
target[targetIndex++] = 61 << 2;
target[targetIndex++] = (byte)len;
target[targetIndex++] = (byte)(len >> 8);
}
else if (len < 0x1000000)
{
target[targetIndex++] = 62 << 2;
target[targetIndex++] = (byte)len;
target[targetIndex++] = (byte)(len >> 8);
target[targetIndex++] = (byte)(len >> 16);
}
else
{
target[targetIndex++] = 63 << 2;
target[targetIndex++] = (byte)len;
target[targetIndex++] = (byte)(len >> 8);
target[targetIndex++] = (byte)(len >> 16);
target[targetIndex++] = (byte)(len >> 24);
}
Array.Copy(inputBytes, lasthit, target, targetIndex, i + offset - lasthit);
targetIndex += i - lasthit;
lasthit = i;
}
if (h.Length <= 11 && h.Offset < 2048)
{
target[targetIndex] = 1;
target[targetIndex] |= (byte)((h.Length - 4) << 2);
target[targetIndex++] |= (byte)((h.Offset >> 3) & 0xe0);
target[targetIndex++] = (byte)(h.Offset & 0xff);
}
else if (h.Offset < 65536)
{
target[targetIndex] = 2;
target[targetIndex++] |= (byte)((h.Length - 1) << 2);
target[targetIndex++] = (byte)(h.Offset);
target[targetIndex++] = (byte)(h.Offset >> 8);
}
else
{
target[targetIndex] = 3;
target[targetIndex++] |= (byte)((h.Length - 1) << 2);
target[targetIndex++] = (byte)(h.Offset);
target[targetIndex++] = (byte)(h.Offset >> 8);
target[targetIndex++] = (byte)(h.Offset >> 16);
target[targetIndex++] = (byte)(h.Offset >> 24);
}
for (; i < lasthit; i++)
{
if (i + 4 < inputBytes.Length)
{
ilhm[ToInt(inputBytes, i) % ilhm.Length] = i;
}
}
lasthit = i + h.Length;
while (i < lasthit - 1)
{
if (i + 4 < inputBytes.Length)
{
ilhm[ToInt(inputBytes, i) % ilhm.Length] = i;
}
i++;
}
}
else
{
if (i + 4 < length)
{
ilhm[ToInt(inputBytes, i) % ilhm.Length] = i;
}
}
}
if (lasthit < offset + length)
{
int len = (offset + length) - lasthit - 1;
if (len < 60)
{
target[targetIndex++] = (byte)(len << 2);
}
else if (len < 0x100)
{
target[targetIndex++] = 60 << 2;
target[targetIndex++] = (byte)len;
}
else if (len < 0x10000)
{
target[targetIndex++] = 61 << 2;
target[targetIndex++] = (byte)len;
target[targetIndex++] = (byte)(len >> 8);
}
else if (len < 0x1000000)
{
target[targetIndex++] = 62 << 2;
target[targetIndex++] = (byte)len;
target[targetIndex++] = (byte)(len >> 8);
target[targetIndex++] = (byte)(len >> 16);
}
else
{
target[targetIndex++] = 63 << 2;
target[targetIndex++] = (byte)len;
target[targetIndex++] = (byte)(len >> 8);
target[targetIndex++] = (byte)(len >> 16);
target[targetIndex++] = (byte)(len >> 24);
}
Array.ConstrainedCopy(inputBytes, lasthit, target, targetIndex, length + offset - lasthit);
targetIndex += length - lasthit;
}
buffer.Length = targetIndex + offset;
return(buffer);
}
private static Hit Search(byte[] source, int index, int length, IntListHashMap map, bool useFirstHit)
{
if (index + 4 >= length)
{
return null;
}
if (index > 0 &&
source[index] == source[index - 1] &&
source[index] == source[index + 1] &&
source[index] == source[index + 2] &&
source[index] == source[index + 3])
{
int len = 0;
for (int i = index; len < 64 && i < length && source[index] == source[i]; i++, len++)
{
}
return new Hit(1, len);
}
if (useFirstHit)
{
int fp = map.GetFirstHit(ToInt(source, index), index - 4);
if (fp < 0)
{
return null;
}
int offset = index - fp;
int l = 0;
for (int o = fp, io = index; io < length && source[o] == source[io] && o < index && l < 64; o++, io++)
{
l++;
}
return new Hit(offset, l);
}
IEnumerable<int> ii = map.GetReverse(ToInt(source, index));
Hit res = null;
foreach (int fp in ii)
{
int offset = index - fp;
if (offset > DefaultMaxOffset)
{
break;
}
if (offset >= 4)
{
int l = 0;
for (int o = index - offset, io = index; io < length && source[o] == source[io] && o < index && l < 64; o++, io++)
{
l++;
}
if (res == null)
{
res = new Hit(offset, l);
}
else if (l > res.Length)
{
res.Offset = offset;
res.Length = l;
}
}
}
return res;
}
private static Hit Search(byte[] source, int index, int length, IntListHashMap map, bool useFirstHit)
{
if (index + 4 >= length)
{
return(null);
}
if (index > 0 &&
source[index] == source[index - 1] &&
source[index] == source[index + 1] &&
source[index] == source[index + 2] &&
source[index] == source[index + 3])
{
int len = 0;
for (int i = index; len < 64 && i < length && source[index] == source[i]; i++, len++)
{
}
return(new Hit(1, len));
}
if (useFirstHit)
{
int fp = map.GetFirstHit(ToInt(source, index), index - 4);
if (fp < 0)
{
return(null);
}
int offset = index - fp;
int l = 0;
for (int o = fp, io = index; io < length && source[o] == source[io] && o < index && l < 64; o++, io++)
{
l++;
}
return(new Hit(offset, l));
}
IEnumerable <int> ii = map.GetReverse(ToInt(source, index));
Hit res = null;
foreach (int fp in ii)
{
int offset = index - fp;
if (offset > DefaultMaxOffset)
{
break;
}
if (offset >= 4)
{
int l = 0;
for (int o = index - offset, io = index; io < length && source[o] == source[io] && o < index && l < 64; o++, io++)
{
l++;
}
if (res == null)
{
res = new Hit(offset, l);
}
else if (l > res.Length)
{
res.Offset = offset;
res.Length = l;
}
}
}
return(res);
}