/// <summary>
/// Construct instance with pending buffer
/// </summary>
/// <param name="pending">
/// Pending buffer to use
/// </param>
public DeflaterEngine(DeflaterPending pending)
{
this.pending = pending;
huffman = new DeflaterHuffman(pending);
window = new byte[2 * DeflaterConstants.WSIZE];
head = new short[DeflaterConstants.HASH_SIZE];
prev = new short[DeflaterConstants.WSIZE];
// We start at index 1, to avoid an implementation deficiency, that
// we cannot build a repeat pattern at index 0.
blockStart = strstart = 1;
}
private void BuildTree(IList <byte> codeLengths)
{
int[] blCount = new int[MAX_BITLEN + 1];
int[] nextCode = new int[MAX_BITLEN + 1];
for (int i = 0; i < codeLengths.Count; i++)
{
int bits = codeLengths[i];
if (bits > 0)
{
blCount[bits]++;
}
}
int code = 0;
int treeSize = 512;
for (int bits = 1; bits <= MAX_BITLEN; bits++)
{
nextCode[bits] = code;
code += blCount[bits] << (16 - bits);
if (bits >= 10)
{
/* We need an extra table for bit lengths >= 10. */
int start = nextCode[bits] & 0x1ff80;
int end = code & 0x1ff80;
treeSize += (end - start) >> (16 - bits);
}
}
/* Now create and fill the extra tables from longest to shortest
* bit len. This way the sub trees will be aligned.
*/
tree = new short[treeSize];
int treePtr = 512;
for (int bits = MAX_BITLEN; bits >= 10; bits--)
{
int end = code & 0x1ff80;
code -= blCount[bits] << (16 - bits);
int start = code & 0x1ff80;
for (int i = start; i < end; i += 1 << 7)
{
tree[DeflaterHuffman.BitReverse(i)] = (short)((-treePtr << 4) | bits);
treePtr += 1 << (bits - 9);
}
}
for (int i = 0; i < codeLengths.Count; i++)
{
int bits = codeLengths[i];
if (bits == 0)
{
continue;
}
code = nextCode[bits];
int revcode = DeflaterHuffman.BitReverse(code);
if (bits <= 9)
{
do
{
tree[revcode] = (short)((i << 4) | bits);
revcode += 1 << bits;
} while (revcode < 512);
}
else
{
int subTree = tree[revcode & 511];
int treeLen = 1 << (subTree & 15);
subTree = -(subTree >> 4);
do
{
tree[subTree | (revcode >> 9)] = (short)((i << 4) | bits);
revcode += 1 << bits;
} while (revcode < treeLen);
}
nextCode[bits] = code + (1 << (16 - bits));
}
}