public bool TryFastAppend(Pointer ip, int available, int len)
{
int spaceLeft = _length - _index;
if (len > 16 || available < 16 || spaceLeft < 16)
{
return(false);
}
var op = new Pointer(_buffer, _index);
op.Copy64(ip);
op.Copy64(ip + 8, 8);
_index += len;
return(true);
}
private void IncrementalCopyFastPath(Pointer src, Pointer op, int len)
{
while (op - src < 8)
{
op.Copy64(src);
len -= op - src;
op += op - src;
}
while (len > 0)
{
op.Copy64(src);
src += 8;
op += 8;
len -= 8;
}
}
private static Pointer EmitLiteral(Pointer dest, Pointer literal, int length, bool allowFastPath)
{
int n = length - 1;
if (n < 60)
{
var value = CompressorTag.Literal | (n << 2);
dest[0] = (byte)value;
dest += 1;
if (allowFastPath && length <= 16)
{
dest.Copy64(literal);
dest.Copy64(literal + 8, offset: 8);
return(dest + length);
}
}
else
{
var tmp = new Pointer(dest);
dest += 1;
int count = 0;
while (n > 0)
{
dest[count] = (byte)(n & 0xff);
n >>= 8;
count++;
}
Debug.Assert(count >= 1);
Debug.Assert(count <= 4);
tmp[0] = (byte)(CompressorTag.Literal | (59 + count) << 2);
dest += count;
}
dest.Copy(literal, length);
return(dest + length);
}
public bool AppendFromSelf(int offset, int len)
{
int spaceLeft = _length - _index;
if (_index <= offset - 1u)
{ // -1u catches offset==0
return(false);
}
var op = new Pointer(_buffer, _index);
if (len <= 16 && offset >= 8 && spaceLeft >= 16)
{
var src = new Pointer(_buffer, _index - offset);
op.Copy64(src);
op.Copy64(src + 8, offset: 8);
}
else
{
if (spaceLeft >= len + CompressorConstants.MaxIncrementCopyOverflow)
{
IncrementalCopyFastPath(op - offset, op, len);
}
else
{
if (spaceLeft < len)
{
return(false);
}
IncrementalCopy(op - offset, op, len);
}
}
_index += len;
return(true);
}