[Small Tutorial] Packets in Conquer Online

[Korvacs]

Originally Posted by I don't have a username

Obviously it wouldn't be Int8 as you can't send signed integers in a packet. Well not true there is a way you can, you could do something like:

bool negative
signed integer

However it's not a real way to do it, but it's equal to the way negative values are stored in your machine.

lolwut?

Of course you can send a signed int in a packet, the fact that it doesn't look like one in the packet doesn't mean its not signed, its how the data is interpreted at the other end which matters, hell TQ even use a signed int in the character info and status change packets, that's how incorrect this statement is.

As for the article, i believe that this is probably one of the best pieces of content now on this section of the forum. Its going to help alot of new people better understand what packets actually are and how to modify them.

[I don't have a username]

Originally Posted by Korvacs

lolwut?

Of course you can send a signed int in a packet, the fact that it doesn't look like one in the packet doesn't mean its not signed, its how the data is interpreted at the other end which matters, hell TQ even use a signed int in the character info and status change packets, that's how incorrect this statement is.

As for the article, i believe that this is probably one of the best pieces of content now on this section of the forum. Its going to help alot of new people better understand what packets actually are and how to modify them.

But signed integers are way different from unsigned, because you cannot store negative values, you store a bit along with the value. Just what I think, since it's like that in assembly programming, then I assume this works same way as you still store data in memory.

Originally Posted by pcasm

Integers come in two flavors: unsigned and signed. Unsigned integers
(which are non-negative) are represented in a very straightforward binary
manner. The number 200 as an one byte unsigned integer would be represented
as by 11001000 (or C8 in hex).
Signed integers (which may be positive or negative) are represented in a
more complicated ways. For example, consider −56. +56 as a byte would be
represented by 00111000. On paper, one could represent −56 as −111000,
but how would this be represented in a byte in the computer’s memory. How
would the minus sign be stored?
There are three general techniques that have been used to represent
signed integers in computer memory. All of these methods use the most
significant bit of the integer as a sign bit. This bit is 0 if the number is
positive and 1 if negative.

[Korvacs]

Yes you are correct and in the event that a negative number must be sent through a packet then this method is still used, so you are still sending a signed integer through a packet. The client does this at least twice, where a negative number is legitimately used.

Im not really sure what your point is beyond that you seem to believe you cant send a negative number in a data packet...

[CptSky]

Why we couldn't send a signed integer? What is the difference between a Int8 and a UInt8? You said it. It's the first bit that is used by the signed one to determine if it's negative or positive. But when you send the two integer over internet, we convince that both of them are coded on 8 bits, an octet. And, what we send over TCP/IP is actually a buffer of octets. So, all type that can be divided in 8 bits chunk can be send. A float can be sent because it's formed of 4 octets. A signed 32 bits integer can be sent because it's formed of 4 octets. It doesn't matter what is the original type as it's only octets that is sent.

The client and the server should know how to format the raw data and it's the protocol.

Oh, and as everything is sent in octet, there is an order to respect to get the right value. With the Internet Protocol, integers should be wrote using the big endian order. And, swapped by the client/server at receive. TQ seems to don't respect that because they use the little endian order... But as they only work on little-endian architecture (Windows and now on Intel Mac), that just remove swapping.

[Korvacs]

So yeah, all in all bauss:

Originally Posted by Korvacs

If you don't know what your talking about, then stop talking.

[amonaptra]

Impressive work , Keep it up <3

[Spirited]

Originally Posted by amonaptra

Impressive work , Keep it up <3

I created a second tutorial here that (I think) does a slightly better job:

[zakkwilde_17]

request to repost the images

[Spirited]

Originally Posted by zakkwilde_17

request to repost the images

No. I made a second tutorial and a third tutorial after this. Literally wrote this last week...

Last post from 2013... come on. Request close.

[wshbr]

#closed as request