public static int Decode(byte[] src, int srcpos, byte[] dst, int dstpos, int srclen, bool reverse = false)
{
int dstofs = dstpos;
while (srcpos < srclen)
{
int cmd = FastBinaryStream.ReadByte(src, ref srcpos);
// case 2
if ((cmd & 0x80) == 0)
{
int count = ((cmd & 0x70) >> 4) + 3;
int relpos = ((cmd & 0x0f) << 8) + FastBinaryStream.ReadByte(src, ref srcpos);
if (dstpos + count > dst.Length)
{
return(dstpos);
}
ReplicatePrevious(dst, ref dstpos, dstpos - relpos, count);
}
// case 1
else if ((cmd & 0x40) == 0)
{
int count = cmd & 0x3f;
if (count == 0)
{
break;
}
FastBinaryStream.Copy(src, ref srcpos, dst, ref dstpos, count);
}
else
{
cmd &= 0x3f;
// case 4
if (cmd == 0x3e)
{
var count = FastBinaryStream.ReadWord(src, ref srcpos);
var color = FastBinaryStream.ReadByte(src, ref srcpos);
for (int end = dstpos + count; dstpos < end; dstpos++)
{
dst[dstpos] = color;
}
}
// case 5
else if (cmd == 0x3f)
{
int count = FastBinaryStream.ReadWord(src, ref srcpos);
int cpypos = FastBinaryStream.ReadWord(src, ref srcpos) + dstofs;
if (reverse)
{
cpypos = dstpos - cpypos;
}
if (cpypos >= dstpos)
{
throw new IndexOutOfRangeException("cpypos >= dstpos");
}
for (int end = dstpos + count; dstpos < end; dstpos++)
{
dst[dstpos] = dst[cpypos++];
}
}
// case 3
else
{
int count = cmd + 3;
int cpypos = FastBinaryStream.ReadWord(src, ref srcpos) + dstofs;
if (reverse)
{
cpypos = dstpos - cpypos;
}
if (cpypos >= dstpos)
{
throw new IndexOutOfRangeException("cpypos >= dstpos");
}
for (int end = dstpos + count; dstpos < end; dstpos++)
{
dst[dstpos] = dst[cpypos++];
}
}
}
}
return(dstpos);
}
public static void Decode(byte[] src, int srclen, byte[] dst, byte[] bse)
{
int srcpos = 0;
int dstpos = 0;
int bsepos = 0;
int count = 0;
while (srcpos < srclen)
{
int cmd = FastBinaryStream.ReadByte(src, ref srcpos);
if ((cmd & 0x80) == 0)
{
// 00000000 c*8 v*8 = xor next c bytes with v
if (cmd == 0)
{
count = FastBinaryStream.ReadByte(src, ref srcpos);
byte color = FastBinaryStream.ReadByte(src, ref srcpos);
while (count-- > 0)
{
dst[dstpos++] = (byte)(bse[bsepos++] ^ color);
}
}
// 0ccccccc = xor the next c bytes from source with those in base
else
{
count = cmd;
while (count-- > 0)
{
dst[dstpos++] = (byte)(src[srcpos++] ^ bse[bsepos++]);
}
}
}
else
{
count = cmd & 0x7f;
if (count == 0)
{
count = FastBinaryStream.ReadWord(src, ref srcpos);
cmd = count >> 8;
// 10000000 0ccccccc c*8 = large copy base to dest for count
if ((cmd & 0x80) == 0)
{
if (count == 0)
{
return;
}
FastBinaryStream.Copy(bse, ref bsepos, dst, ref dstpos, count);
}
else
{
count &= 0x3fff;
// 10000000 10cccccc c*8 = xor the next c bytes from source with those in base
if ((cmd & 0x40) == 0)
{
while (count-- > 0)
{
dst[dstpos++] = (byte)(src[srcpos++] ^ bse[bsepos++]);
}
}
// 10000000 11cccccc c*8 v*8
else
{
byte fill = src[srcpos++];
while (count-- > 0)
{
dst[dstpos++] = (byte)(bse[bsepos++] ^ fill);
}
}
}
}
// 1ccccccc = small copy base to dest for count
else
{
FastBinaryStream.Copy(bse, ref bsepos, dst, ref dstpos, count);
}
}
}
}