Difference between revisions of "LFS Programming"

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== Introduction ==
 
== Introduction ==
  
LFS is a very programmer friendly game, and while official modification of the game engine is not allowed, there are many ways that addon writers can cutomise and control the playing experience. This section of the wiki details several ways of doing this, as well as other general programmer related information.  
+
By its nature LFS is a very programmer friendly game and, while customisation of the game engine itself is frowned upon, there are many other avenues available for budding addon writers to explore. Whether it's parsing some esoteric file format, writing your own server system, or just grabbing your friend's hotlaps from LFSWorld, LFS has something to keep even the most adventurous hackers busy!
 +
 
 +
The following category attempts to explain and document the many various programmer topics related to LFS, in hopefully a clear and useful way. Our job of course is not to teach you how to program, there are many, many books about that, but to show you the myriad possibilities for customising LFS which are right at your fingertips.
  
 
== Programming Categories ==
 
== Programming Categories ==
Line 8: Line 10:
  
 
[[InSim]] is a protocol which allows an external program to communicate with Live for Speed. It allows you to create a socket connection with the game and to send and receive packets of data. The InSim protocol describes how each of these packets is formatted, and any programming language which can create a network connection and send and receive strings of binary data can interface with it.
 
[[InSim]] is a protocol which allows an external program to communicate with Live for Speed. It allows you to create a socket connection with the game and to send and receive packets of data. The InSim protocol describes how each of these packets is formatted, and any programming language which can create a network connection and send and receive strings of binary data can interface with it.
 +
 +
=== InSim Relay ===
 +
 +
With [[InSim Relay]] you can connect to any subscribed host and share a subset of InSim packets. This is mainly used in the creation of spectator style apps, such as LFSRemote.
  
 
=== OutSim / OutGauge ===
 
=== OutSim / OutGauge ===
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=== LFSWorld stats ===
 
=== LFSWorld stats ===
  
Through the use of [[LFSWorld stats]], addon programmers are able to query the LFSWorld Web site for a whole host of information about the racers who play the game and the servers they play on.
+
Through the use of [http://www.lfsforum.net/showthread.php?t=14480 LFSWorld stats], addon programmers are able to query the LFSWorld Web site for a whole host of information about the racers who play the game and the servers they play on.
  
 
=== File Formats ===
 
=== File Formats ===
Line 25: Line 31:
 
=== Data-Types ===
 
=== Data-Types ===
  
LFS is written in the C++ programming language and many of data-types used are from that language. Here is a break-down of the various data-types used by LFS and what they mean.
+
The LFS game client itself is written in C++ and many of data-types referenced throughout the documentation are named in accordance with that language. The following table represents a breakdown of what each data-type means and what sort of value it holds.
  
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"
+
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="800"
! colspan="3" style="background-color: #0066CC; color:#FFFFFF;" |'''Data-Types'''
+
! colspan="4" style="background-color: #0066CC; color:#FFFFFF;" |'''Data-Types'''
 
|- style="background-color: #DFDFDF;"
 
|- style="background-color: #DFDFDF;"
 
! style="border: 1px solid #000000;" | LFS
 
! style="border: 1px solid #000000;" | LFS
! style="border: 1px solid #000000;" | Type
+
! style="border: 1px solid #000000;" | Data Type
 +
! style="border: 1px solid #000000;" | PHP Pack Type
 
! style="border: 1px solid #000000;" | Description
 
! style="border: 1px solid #000000;" | Description
 
|-
 
|-
 
| char
 
| char
| 1 byte unsigned character
+
| 1 byte signed integer
| A character from the alphabet
+
| a or C
 +
| An alphanumeric character (or a number between -128 to 127)
 
|-
 
|-
 
| byte
 
| byte
 
| 1 byte unsigned integer
 
| 1 byte unsigned integer
 +
| C
 
| A number between 0 and 255
 
| A number between 0 and 255
 
|-
 
|-
 
| word
 
| word
 
| 2 byte unsigned integer
 
| 2 byte unsigned integer
 +
| v
 
| A number between 0 and 65,535
 
| A number between 0 and 65,535
 
|-
 
|-
 
| short
 
| short
 
| 2 byte signed integer
 
| 2 byte signed integer
| A number between −32,768 and +32,767
+
| s
 +
| A number between -32,768 and +32,767
 
|-
 
|-
 
| unsigned
 
| unsigned
 
| 4 byte unsigned integer
 
| 4 byte unsigned integer
 +
| V
 
| A number between 0 and +4,294,967,295
 
| A number between 0 and +4,294,967,295
 
|-
 
|-
 
| int
 
| int
 
| 4 byte signed integer
 
| 4 byte signed integer
| A number between −2,147,483,648 and +2,147,483,647
+
| l
 +
| A number between -2,147,483,648 and +2,147,483,647
 
|-
 
|-
 
| float
 
| float
 
| 4 byte floating point number
 
| 4 byte floating point number
 +
| f
 
| A number with a decimal point
 
| A number with a decimal point
 
|}
 
|}
  
 +
In C strings are not first-class data-types, merely arrays of characters, so you will often see strings denoted using the following syntax.
 +
 +
<big><pre>char[16] <variable></pre></big>
 +
 +
This indicates that the variable is a string of 16 characters in length, but in reality as the last character in a C-style string is always NULL, it would only be able to hold a value of 15 characters. For php in this case, you would use the 'a' as the pack format code, with a 16 following after it's declaration.
 +
 +
For example:
 +
<pre>pack('a16', $variable);</pre>
  
 
=== LFS Strings and Escape Codes ===
 
=== LFS Strings and Escape Codes ===
  
LFS does not support unicode strings and instead uses it's own system of character escape codes.  
+
Strings in LFS are C-style strings, meaning that they end with a NULL character, or are often padded with NULL characters. Most other high-level languages have done away with this limitation, so it's important to strip any NULL characters from the end of a string before using it.
 +
 
 +
LFS handles strings in its own way, it uses Windows codepages sepearared by special escape characters.
 +
----
 +
. The following table represents an attempt to document each of these codepages. In reality it's not 100% accurate, in practice it should give you reasonable results for most purposes.
  
 
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"
 
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"
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| ^G
 
| ^G
 
| Greek
 
| Greek
| ISO-8859-7
+
| CP1253
 
|-
 
|-
 
| ^C
 
| ^C
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| ^J
 
| ^J
 
| Japanese
 
| Japanese
| Shift-JIS
+
| CP932
 
|-
 
|-
 
| ^E
 
| ^E
 
| Central Europe
 
| Central Europe
| ISO-8859-2
+
| CP1250
 
|-
 
|-
 
| ^T
 
| ^T
 
| Turkish
 
| Turkish
| ISO-8859-9
+
| CP1254
 
|-
 
|-
 
| ^B
 
| ^B
 
| Baltic
 
| Baltic
| ISO-8859-13
+
| CP1257
 
|-
 
|-
 
| ^H
 
| ^H
 
| Traditional Chinese
 
| Traditional Chinese
| CP936
+
| CP950
 
|-
 
|-
 
| ^S
 
| ^S
| Simpified Chinese
+
| Simplified Chinese
| CP949
+
| CP936
 
|-
 
|-
 
| ^K
 
| ^K
 
| Korean
 
| Korean
| CP950
+
| CP949
 
|}
 
|}
  
 +
In addition there are several other escape codes which denote special characters in text.
  
 
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"
 
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"
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|-
 
|-
 
| ^v  
 
| ^v  
| |
+
| <nowiki>|</nowiki>
 
|-
 
|-
 
| ^a
 
| ^a
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| ^r
 
| ^r
 
| >
 
| >
 +
|-
 +
| ^h
 +
| #
 +
|-
 +
| ^^
 +
| ^
 
|}
 
|}
  
 +
And finally the colour of text is also denoted using escape codes, a table of which can be found below.
  
 
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"
 
{| border="0" style="border: 1px solid #000000; background-color: #FAFAFA;" width="600"

Latest revision as of 00:26, 12 February 2016

Introduction

By its nature LFS is a very programmer friendly game and, while customisation of the game engine itself is frowned upon, there are many other avenues available for budding addon writers to explore. Whether it's parsing some esoteric file format, writing your own server system, or just grabbing your friend's hotlaps from LFSWorld, LFS has something to keep even the most adventurous hackers busy!

The following category attempts to explain and document the many various programmer topics related to LFS, in hopefully a clear and useful way. Our job of course is not to teach you how to program, there are many, many books about that, but to show you the myriad possibilities for customising LFS which are right at your fingertips.

Programming Categories

InSim

InSim is a protocol which allows an external program to communicate with Live for Speed. It allows you to create a socket connection with the game and to send and receive packets of data. The InSim protocol describes how each of these packets is formatted, and any programming language which can create a network connection and send and receive strings of binary data can interface with it.

InSim Relay

With InSim Relay you can connect to any subscribed host and share a subset of InSim packets. This is mainly used in the creation of spectator style apps, such as LFSRemote.

OutSim / OutGauge

Similar to InSim, OutSim and OutGauge also allow you to create a socket connection from an external program, but specifically for the support of motion simulators and external dashboards.

LFSWorld stats

Through the use of LFSWorld stats, addon programmers are able to query the LFSWorld Web site for a whole host of information about the racers who play the game and the servers they play on.

File Formats

Many of LFS's unique file formats have been documented, both officially by the development team, and unofficially by enthusiastic hackers with hex-editors.

General Programming Information

Data-Types

The LFS game client itself is written in C++ and many of data-types referenced throughout the documentation are named in accordance with that language. The following table represents a breakdown of what each data-type means and what sort of value it holds.

Data-Types
LFS Data Type PHP Pack Type Description
char 1 byte signed integer a or C An alphanumeric character (or a number between -128 to 127)
byte 1 byte unsigned integer C A number between 0 and 255
word 2 byte unsigned integer v A number between 0 and 65,535
short 2 byte signed integer s A number between -32,768 and +32,767
unsigned 4 byte unsigned integer V A number between 0 and +4,294,967,295
int 4 byte signed integer l A number between -2,147,483,648 and +2,147,483,647
float 4 byte floating point number f A number with a decimal point

In C strings are not first-class data-types, merely arrays of characters, so you will often see strings denoted using the following syntax.

char[16] <variable>

This indicates that the variable is a string of 16 characters in length, but in reality as the last character in a C-style string is always NULL, it would only be able to hold a value of 15 characters. For php in this case, you would use the 'a' as the pack format code, with a 16 following after it's declaration.

For example:

pack('a16', $variable);

LFS Strings and Escape Codes

Strings in LFS are C-style strings, meaning that they end with a NULL character, or are often padded with NULL characters. Most other high-level languages have done away with this limitation, so it's important to strip any NULL characters from the end of a string before using it.

LFS handles strings in its own way, it uses Windows codepages sepearared by special escape characters.


. The following table represents an attempt to document each of these codepages. In reality it's not 100% accurate, in practice it should give you reasonable results for most purposes.

Codepages
Code Name Codepage
^L Latin 1 CP1252
^G Greek CP1253
^C Cyrillic CP1251
^J Japanese CP932
^E Central Europe CP1250
^T Turkish CP1254
^B Baltic CP1257
^H Traditional Chinese CP950
^S Simplified Chinese CP936
^K Korean CP949

In addition there are several other escape codes which denote special characters in text.

Escape Codes
Code Character
^v |
^a *
^c  :
^d \
^s /
^q  ?
^t "
^l <
^r >
^h #
^^ ^

And finally the colour of text is also denoted using escape codes, a table of which can be found below.

Colours
Code Colour
^0 Black
^1 Red
^2 Light green
^3 Yellow
^4 Blue
^5 Purple
^6 Light blue
^7 White
^8 Dark green (default)
^9 Original text colour and codepage.