SCM language

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Revision as of 13:52, 5 December 2012 by Wesser (talk | contribs) (Corrected a little mistake.)
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This section deals with the native SCM syntax of GTA 3 series, nothing other than III, VC, SA, LCS and VCS.
It may contain non-standard SCM definitions as R* hasn't published enough documentation about it yet.

On the occasion of the GTAIII's tenth anniversary, after a long period of darkness where we fell about the real SCM syntax, R* finally treated us by attaching part of its own original source code into the GTAIII Anniversary game, available for iOS and Android devices. As far back as 2001, a snip of some debugging scripts has been already provided with main.sc and debug.sc files. However, many secrets are unrevealed yet, thus some things cannot be documented fully and so they can be only guessed. The SCM format abbreviation is one of countless proofs of this inconvenience, which may stand for Script Control Merged. Other doubts come with source files, whose SC extension appears to be very close to Script Control. At first, someone could have asked oneself how R* named its own programming language: R#? R-Sharp? Rockstar Sharp? Who knows. We simply call it SCM language due to the lack of information. Nevertheless, the SCR language name is cropping up gradually.


Preliminary remarks


This article makes use of formatted codes to improve the reading comprehension. Note that:

  • Square brackets mean everything inside may be omitted.
  • Curly brackets denote the presence of useful codes but not necessarily needed.
  • Vertical bars divide what can be chosen alternatively.

Fundamentals

Comments

A comment is an additional text that may be helpful for the code writer or other users, in short for the reader. It is the only part of the source code which gets always ignored when compiling.

Inline

An inline comment, denoted by // (two slashes), makes everything that follows some plain text:

[...] // Some inline comment

Multiline

A multiline comment embraces a particular area of the source code, starting by the opening tag /* (slash and asterisk) and ending with */ (asterisk and slash):

[...]
/*
 * Some multiline comment
 * ...
 */
[...]

Currently, more than one multiline comment is allowed per line:

[...] /* Some inline comment */ [...] /* Some inline comment */ [...]
Limit
Multiline comments cannot be nested.

Brackets

Brackets play an important role, especially when organizing multiple scripts in a single file becomes necessary.

Curly brackets

Curly brackets (or multiline brackets) act like a local variable scope. Essentially, they enclose the code where local variables are used, including timers. They can be opened and closed many times in a script:

{
    [...]
}

Round brackets

Actually, the round brakets (or multi inline brackets) behaviour sounds trivial, that's to say they simply highlight one or more arguments per command, individually or together. In GTA III, they appear to be used only for SETUP_ZONE_PED_INFO (in a various order) and GXT keys:

SETUP_ZONE_PED_INFO FISHFAC DAY (0) 0 0 0 (0 0 0 0) 0
PRINT_BIG (T4X4_1) 5000 2

They might lock up null values.

Labels

A label is a sequence of characters which identifiy a location of the source code useful for jumps. It can be accessed by any part of the source code. To define a label just append : (colon) to its name:

[...]

{lblname}:

[...]

At the compiling time, they are automatically converted into an offset.

Variables

A variable is a storage location assigned to a symbolic name which contains a value of any type.

Scope


The usage of a variable depends on the scope, that is the context where a specific variable is declared. At this point, we can distinguish the global and local scope.

Global

The global scope grasps the whole source code. Variables defined as globals are visible in any script. They are declared by appending the VAR prefix.

Local


The local scope wraps a localized part of the source code. Variables defined as locals are visible only in the code enclosed by curly brackets. They are declared by appending the LVAR prefix.

Timers

A timer is a singular local variable whose value rises automatically. It starts incrementing since the beginning of the script where it has been placed and grows endlessly. There are 2 usable timers which are already defined as TIMERA and TIMERB, therefore they do not need to be declared.

Types


Among the available types, some are equivalent to the most known programming types. Their length is up to 4, 8 and 16 bytes. Each type is appended as a suffix in the variable declaration.

INT

The INT type handles 32-bit signed integer values. It is also used to store values with less bytes, such as a bool, a char and a short int.

FLOAT

The FLOAT type handles 32-bit floating-point values. As it normally does, decimal precision is usually stuck to 6 digits beyond which it may get lost.

CONST

CONST is a special type that handles 32-bit signed integer values. It is used only to compare constants of model identifiers, task statuses, ped events and such. It mightn't be used directly but divided into other subordinal types. At the moment, it is merely a suggestion because constants are processed in bulk apparently instead of file by file.

Limit
CONST variables are supported since Vice City.

STRING

The STRING type handles 8-byte strings. Generally, a string is an array of 1-byte characters. It often requires 7 characters plus the null-terminator (a blank byte meaning the end of the string). It is used to hold GXT keys (those of town zones, interiors, help textes or dialogue subtitles) or script names.

Limit
STRING variables are supported in San Andreas and Vice City Stories.

NAME

The NAME type handles 16-byte strings. Like the previous type, it often holds 15 characters plus the null-terminator. It is used to store model and texture names of player clothes or animation names. It may be a ghost type as R*'s compiler might choose between the two string types automatically according to the length of the string itself.

Limit
It is supported in San Andreas.

Declaration


Defining a variable means assigning a token string to a memory cell at the compiling time. Variables must be declared in the following manner:

{varscope}_{vartype} {varname0}[,] [... {varnameN}]

As mentioned in the sections above, local variables have to be put within curly brackets:

{
    {varscope}_{vartype} {varname0}[,] [... {varnameN}]

    [...]
}

Inline variable declaration is allowed, you just have to separate them by spaces or tabulations. Adding a preceding comma before these characters is optional.

Limit
Whereas the variable buffer is limited, you can declare a certain amount of globals and locals. Numerical (INT, FLOAT) and special (CONST) types take 1 variable, while string types (STRING, NAME) occupy respectively 2 and 4 variables to store some data (have a look here for further details).

Arrays

A array is a collection of variables having the same type which can be accessed by an index, an integer value enclosed by square brackets:

{varscope}_{vartype} {varname0}{[arrsize0]}[,] [... {varnameN}{[arrsizeN]}]
Limit
It is supported since San Andreas.

Operators

In general, an operator is a token string that represents a math calculation or an operation of any other kind, in order to make the code understanding clearer at a glance.

Arithmetic

Arithmetic operators compute some of the most common algebric calculations between either a variable and a value or two variables. As well as in some programming language happens, string (STRING, NAME) and special (CONST) types are free from these operators, except for the basic assigment (see also Operators composition):

Operator Name Syntax Description
= Assignment expr0 = expr1 Store expr1 to expr0
+ Addition expr0 + expr1 Add expr1 to expr0
- Subtraction expr0 - expr1 Subtract expr1 to expr0
* Multiplication expr0 * expr1 Multiply expr0 by expr1
/ Division expr0 / expr1 Divide expr0 by expr1
++ Increment Pre[*] ++ expr0 Increment expr0 by 1 and store the result to expr0
Post expr0 ++
-- Decrement Pre[*] -- expr0 Decrement expr0 by 1 and store the result to expr0
Post expr0 --
Note
^ Pre and post increments have no difference unlike what you would expect.

Yet, you can put the assignment and algebric operators together inline as follows:

Operators Name Syntax Description
= + Addition and assignment expr0 = expr1[*] + expr2 Add expr2 to expr1 and store the result to expr0
= - Subtraction and assignment expr0 = expr1[*] - expr2 Subtract expr2 to expr1 and store the result to expr0
= * Multiplication and assignment expr0 = expr1[*] * expr2 Multiply expr1 by expr2 and store the result to expr0
= / Division and assignment expr0 = expr1[*] / expr2 Divide expr1 by expr2 and store the result to expr0
Note
^ expr1 can represent expr0 too.
Limit
Multiple algebric operators per line are not allowed.

Compound assignment

Compound assignment operators store values or variable's content to other variables having a particular type afterwards the computation of an arithmetic operation, to squeeze the code and clear it up from granted repetitions:

Operator Name Syntax Description
+= Addition assignment expr0 += expr1 Add expr1 to expr0 and store the result to expr0
-= Subtraction assignment expr0 -= expr1 Subtract expr1 to expr0 and store the result to expr0
*= Multiplication assignment expr0 *= expr1 Multiply expr0 by expr1 and store the result to expr0
/= Division assignment expr0 /= expr1 Divide expr0 by expr1 and store the result to expr0

Uncompounded assignment

Uncompounded assignment operators are those on their own, or rather they are neither derivable nor decomposable similarly as those compounds:

Operator Name Syntax Description
=+ Time step addition assignment expr0 =+ expr1 Multiply expr1 by time step, add the result to expr0 and store everything to expr0
=- Time step subtraction assignment expr0 =- expr1 Multiply expr1 by time step, subtract the result to expr0 and store everything to expr0
=# Conversion assignment expr0 =# expr1 Convert expr1 to any other type and store the result to expr0
Limit
Supported conversions are FLOAT to INT and INT to FLOAT.

Logical

Logical operators influence the way conditions are evalueted and enable to test more of them at a time. More than anything, they are built-in statements:

Operators Name Syntax Description
NOT Logical negation IF NOT condition0 Test if condition0 is false
AND Logical conjunction IF condition0
AND condition8
Test if both condition0 and conditionN are true
OR Logical disjunction IF condition0
OR condition8
Test if either condition0 or conditionN is true

Comparison

Comparison operators test the truth or falsity of the relation between either a variable and a value, a value and a variable or two variables:

Operator Name Syntax Description
= Equal to IF expr0 = expr1 Test if expr0 and expr1 are equal
> Greater than IF expr0 > expr1 Test if expr0 is greater than expr1
< Lesser than IF expr0 < expr1 Test if expr0 is lesser than expr1
>= Greater than or equal to IF expr0 >= expr1 Test if expr0 is greater than or equal to expr1
<= Lesser than or equal to IF expr0 <= expr1 Test if expr0 is lesser than or equal to expr1

Theorically, string types (STRING, NAME) should be compared with the first operator only, but the presence of COMPARE_STRING increase the doubts concerning the existence of such operator for strings.

Commands

A command is a symbolic name associated to an opcode which executes a portion of code that specifies the operation to be performed by passing zero or more arguments. Opcodes do not return values that can be assigned to a variable, even though the boolean flag is kept whenever they are used as conditions. It follows the common programming syntax adopted for procedure or function calls:

{commandname} [{anyvalue0|varname0} ... {anyvalueN|varnameN}]

Built-in

Built-in commands are those which are associated to more opcodes that differ each other by argument types or actions:

  • GTA III Vice City San Andreas Liberty City Stories Vice City Stories:
    • OPERATORS
    • ABSI
    • ABSF
  • San Andreas:
    • COMPARE_STRING
    • SAVE_STRING_TO_DEBUG_FILE
    • IS_BIT_SET
    • SET_BIT
    • CLEAR_BIT
    • IS_STRING_NULL
    • STRING_STRING
  • Liberty City Stories Vice City Stories:
    • CALL_FUNCTION

This section is incomplete. You can help by fixing and expanding it.

WAIT

A WAIT skips the execution of a script according to some milliseconds after which it will resume again. Indeed, it is absolutely necessary into infinite loops or those that break after more than one frame, such as the WHILE statement. In this case, a value equal to 0 is passed.

GOTO

A GOTO is the jump to the label of any location of the source code. It is also used internally to build other statements or singularly but then it mustn't point off the current context:

jump0:
GOTO jumpN

[...]

jumpN:
GOTO jump0

Constants

A constant is a symbolic name associated to a specific value. When compiling, their caption is converted in the assigned value. They are listed into TXT files, whose name follows the Pascal Notation which implyies that all first letters of the words are in uppercase and other characters are lowercase (eg. AudioEvents.txt). These files respect the syntax below:

{constname0} {constvalue0}

{constnameN} {constvalueN}

Constant names and values are divided by as many spaces or tabulations as you want. Constant lines are distinguished by two \n (new line) characters. The model names which aren't assigned to a constant are still valid (see also Identifiers).

Others

The arguments of some commands accept only constant values of a single namespace. Instead, the CONST type can hold every constant of any namespace.

This section is incomplete. You can help by fixing and expanding it.

Formatting

Everything is case-insensitive, that means the uppercase and lowercase letters are computed as the same character. Usually, the source code is formatted as shown in this table:

Entity Uppercase Lowercase
Label X
Declaration X
Variable X
Command X
Constant X
Statement X

Compiling

Structure

The source code is split up into several SC files which comprehend main, gosubs, scripts, missions, streams and functions.

Main


Main is the most significant part of the whole source. It consists of a single file that can include many script files through LAUNCH_* and START_* commands. It is characterized by the absence of the local scope.

Gosubs


A gosub is the jump to the label of a subroutine, which executes some code and returns back to the place where it was called with RETURN.

Embedded


Embedded gosubs are those enclosed into a script file. They allow the use of the local scope for timers but they cannot declare local variables. Actually, they can inherit the local scope of the parent script but then they cannot be called by any other script.

Trigger
GOSUB gosub
Code
gosub:
{
    [...]
}
RETURN

File


File gosubs are those included into a script file singularly. LAUNCH_GOSUB jumps to the desired gosub defined into the input file that can call other embedded gosubs or scripts.

Trigger
LAUNCH_GOSUB gosub0 gosub.sc
Code
// File: gosub.sc

:gosub0
{
    [LVAR_{vartype} {varname0}[,] [... {varnameN}]]

    GOSUB gosubN

    [...]
}
RETURN

gosubN:
{
    [...]
}
RETURN
Limit
File gosubs were introduced since GTA III. They were unused in Vice City and got removed in San Andreas, but then they were reimplemented in Liberty City Stories and Vice City Stories.

Scripts


A script is a code block which takes part of a queue of other scripts. As long as it isn't terminated with TERMINATE_THIS_SCRIPT or TERMINATE_ALL_SCRIPTS_WITH_THIS_NAME (elsewhere in another script), its execution never expires till the end of the game process. Each one works independently, even though they are able to share global variables.

Embedded


Embedded scripts are those started by SC files where their body is included into. Note START_NEW_SCRIPT has an undefined amount of arguments which match with each local variable of the starting script.

Trigger
START_NEW_SCRIPT script [{anyvalue0|varname0} ... {anyvalueN|varnameN}]
Code
script:
SCRIPT_NAME script

script_loop:
{
    [LVAR_{vartype} {varname0}[,] [... {varnameN}]]

    [...]
}
//GOTO script_loop
TERMINATE_THIS_SCRIPT

File


File scripts are those which enclose none or more embedded scripts other than their main script. The MISSION opening and closing commands let us supposing scripts that own a SC file are computed as missions. MISSION_START is a special directive which doesn't get compiled, whereas MISSION_END is an alias of TERMINATE_THIS_SCRIPT. Yet, you can also start the scripts embedded in other files.

Trigger
START_TEST_SCRIPT script.sc
Code
// File: script.sc

MISSION_START

[VAR_{vartype} {varname0}[,] [... {varnameN}]]

SCRIPT_NAME main

main_loop:
{
    [LVAR_{vartype} {varname0}[,] [... {varnameN}]]

    START_NEW_SCRIPT script [{anyvalue0|varname0} ... {anyvalueN|varnameN}]

    [...]
}
//GOTO main_loop
MISSION_END

script:
SCRIPT_NAME script

script_loop:
{
    [LVAR_{vartype} {varname0}[,] [... {varnameN}]]

    [...]
}
//GOTO script_loop
TERMINATE_THIS_SCRIPT

Missions


A mission is a script which takes part of the mission block. When it is launched, the pointer is moved to the corresponding mission offset located somewhere in the mission block. Do not forget to begin a mission with MISSION_START (ghost command) and stop its execution with MISSION_END. Although missions are script files, you are able to start embedded scripts, whether they are put in the current file or not.

Trigger

LAUNCH_MISSION mission.sc

Code

// File: mission.sc

MISSION_START

GOSUB mission_start

IF HAS_DEATHARREST_BEEN_EXECUTED
    GOSUB mission_failed
ENDIF

GOSUB mission_cleanup

MISSION_END

[VAR_{vartype} {varname0}[,] [... {varnameN}]]

mission_start:

REGISTER_MISSION_GIVEN
SCRIPT_NAME mission

// Variables initialization

{
    [LVAR_{vartype} {varname0}[,] [... {varnameN}]]

    [...]
}
GOTO mission_passed

mission_failed:
[...]
RETURN

mission_passed:
REGISTER_MISSION_PASSED mission
//PLAYER_MADE_PROGRESS 1
[...]
RETURN

mission_cleanup:
// Mark everything as no longer needed
[...]
RETURN

Streams


This section is incomplete. You can help by fixing and expanding it.

Functions


This section is incomplete. You can help by fixing and expanding it.

Statements

As usual, the evolution of something implies its development over the years. Alongside, the statements implementation has been distributed equally into every chapter. Their definitions are similar to those used in pseudocodes resulting in a raw source code.

IF

IF is one of the most widespread conditional statements which executes some codes by evaluating a boolean flag, also known as a condition. According to the returning value, either the consequence or the alternative will be performed. The condition result can be inverted by appending the NOT logical operator before. More conditions require the use of the remaining logical operators, they are AND, when verifying if all checks are true, and OR, while testing if one of all checks is true. The syntax below summarize the whole explanation:

IF [NOT] {condition0}
[AND|OR [NOT] {condition8}]
    {consequence}
[ELSE
    {alternative}]
ENDIF
Limit
More than 9 conditions per statement are't supported.

WHILE

Alike the IF construct, WHILE is a conditional statement. The only difference consists in how it performs the consequence, that is it loops every line of code built into if the boolean flag is true:

WHILE [NOT] {condition0}
[AND|OR [NOT] {condition8}]
    {consequence}
ENDWHILE

DO-WHILE

DO-WHILE is a variation of the WHILE statement as already stated. It performs the consequence until the boolean flag becomes false. As opposed to its closest relative, the evaluation of the boolean flag happens after the execution of the consequence. Do not mix it with the DO-LOOP construct (not implemented by R*):

DO
    {consequence}
WHILE [NOT] {condition0}
[AND|OR [NOT] {condition8}]
Limits
It is supported since Vice City.

FOR

Similar to the WHILE construct, FOR iterates some code depending on an incremental variable which goes through the given range, whose ending value must be subsequent to its beginning:

FOR {varname} FROM {value0} TO {valueN}
    {consequence}
ENDFOR
Limits
It is supported since San Andreas.
The range accepts only integer values.
Values must be subsequent.
The code will be read at least once in any case.

CASE

Basically, CASE is a group of concatenated IF statements. When a condition is false the next case gets performed, otherwise the consequence is executed and the code jumps to the end of the construct. If none of the cases is true, an ELSE clause may be carried out:

CASE {varname}
    WHEN {value0}
        {consequence}
    [WHEN {valueN}
        {consequence}]
    [ELSE
        {alternative}]
ENDCASE
Limits
It is supported since San Andreas.
The WHEN clause allows the use of integer values only.
In San Andreas, values must be sorted.
Multiple cases per consequence aren't allowed.

Decompiling

Structure

For further information about the SCM file format, read this article. Take into account the compiling order of each SC file is main-gosubs-scripts-missions apart from the reading order of the commands used to include them. streams are compiled individually into the script.img file. On the other hand, functions are compiled like embedded gosubs.

Identifiers

Undefined constants of model identifiers, whose name refers to a DFF which is presumably archived into any of the IMGs, loaded by the game, are overwritten by a decrementing value in the order they get compiled. These model names are then put into the second segment of the SCM header. Those of missions and streams respect the same rule except the fact they are turned into a 0-based growing identifier.

Offsets

An offset is a 32-bit signed integer value which points to a location of the source code. Those within main, gosub and script files are absolute offsets that start from the beginning of the main script, while the ones inside mission and stream files are relative offsets starting from their beginning. The offset is related to global variables aswell, whose interval goes from 8 and ends to FFFC, each one is aligned to the nearest 4 bytes.

Variables

The following table shows the variables range of the local scope for each game version:

Scope GTA III Vice City San Andreas Liberty City Stories Vice City Stories
Gosub 0-15 0-15 n/a 0-95 0-95
Script 0-15 0-15 0-31 0-95 0-95
Mission[*] 0-15 0-15 0-1023 0-95 0-95
Stream n/a n/a 0-31 n/a n/a
Function n/a n/a n/a 0-95 0-95
Timer 16-17 16-17 32-33 10-11? 254-255
Note
^ Although the mission block is allocated as an unique script, locals point to the same storage location, therefore they are some kind of globals for missions uniquely.

Operators composition

As far as you wouldn't know, SCM's operators always take two operands to compute an operation. Their composition is listed below:

Operator/s Name Syntax Composition
++ Increment Pre ++ expr0 expr0 += 1
Post expr0 ++
-- Decrement Pre -- expr0 expr0 -= 1
Post expr0 --
= + Addition and assignment expr0 = expr1 + expr2 expr0 = expr1
expr0 += expr2
= - Subtraction and assignment expr0 = expr1 - expr2 expr0 = expr1
expr0 -= expr2
= * Multiplication and assignment expr0 = expr1 * expr2 expr0 = expr1
expr0 *= expr2
= / Division and assignment expr0 = expr1 / expr2 expr0 = expr1
expr0 /= expr2

Opcodes

An opcode is a 16-bit unsigned integer value referring to a portion of code the game executes when it is called by passing an undefined or absent amount of arguments. The maximum number of available opcodes is 0x7FFF, since the last bit (0x8000) is set whenever they are used as negative conditions (those with the NOT logical operator).

Arguments

An argument is some data given as input to an opcode. Normally, opcodes have a defined amount of arguments up to 32. Those not, such as START_NEW_SCRIPT, can pass as many arguments as the available local variables are, except timers. This limitation is game specific.

Internal

Here is the list of all commands handled arbitrarily by a hypothetical compiler:

Acronym Description Acronym Description Acronym Description Acronym Description Acronym Description
IV INT value FV FLOAT value CV CONST value SV STRING value NV NAME value
GI Global INT GF Global FLOAT GC Global CONST GS Global STRING GN Global NAME
LI Local INT LF Local FLOAT LC Local CONST LS Local STRING LN Local NAME
Command or Operator Opcode Args
count
Arguments
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
GTA III Vice City San Andreas Liberty City Stories Vice City Stories
MISSION_START[*] 0
GOTO[*] 0002 1 IV
GTA III Vice City San Andreas Liberty City Stories
MOVI[*] VN 0004 2 GI IV
0006 LI IV
VV 0084 GI GI
0085 LI LI
008A GI LI
008B LI GI
MOVF[*] VN 0005 2 GF FV
0007 LF FV
VV 0086 GF GF
0087 LF LF
0088 GF LF
0089 LF GF
ADDI[*] VN 0008 2 GI IV
000A LI IV
VV 0058 GI GI
005A LI LI
005C LI GI
005E GI LI
ADDF[*] VN 0009 2 GF FV
000B LF FV
VV 0059 GF GF
005B LF LF
005D LF GF
005F GF LF
SUBI[*] VN 000C 2 GI IV
000E LI IV
VV 0060 GI GI
0062 LI LI
0064 LI GI
0066 GI LI
SUBF[*] VN 000D 2 GF FV
000F LF FV
VV 0061 GF GF
0063 LF LF
0065 LF GF
0067 GF LF
MULI[*] VN 0010 2 GI IV
0012 LI IV
VV 0068 GI GI
006A LI LI
006C GI LI
006E LI GI
MULF[*] VN 0011 2 GF FV
0013 LF FV
VV 0069 GF GF
006B LF LF
006D GF LF
006F LF GF
DIVI[*] VN 0014 2 GI IV
0016 LI IV
VV 0070 GI GI
0072 LI LI
0074 GI LI
0076 LI GI
DIVF[*] VN 0015 2 GF FV
0017 LF FV
VV 0071 GF GF
0073 LF LF
0075 GF LF
0077 LF GF
CMPGI[*] VN 0018 2 GI IV
0019 LI IV
NV 001A IV GI
001B IV LI
VV 001C GI GI
001D LI LI
001E GI LI
001F LI GI
CMPGF[*] VN 0020 2 GF FV
0021 LF FV
NV 0022 FV GF
0023 FV LF
VV 0024 GF GF
0025 LF LF
0026 GF LF
0027 LF GF
CMPGEI[*] VN 0028 2 GI IV
0029 LI IV
NV 002A IV GI
002B IV LI
VV 002C GI GI
002D LI LI
002E GI LI
002F LI GI
CMPGEF[*] VN 0030 2 GF FV
0031 LF FV
NV 0032 FV GF
0033 FV LF
VV 0034 GF GF
0035 LF LF
0036 GF LF
0037 LF GF
CMPEI[*] VN 0038 2 GI IV
0039 LI IV
VV 003A GI GI
003B LI LI
003C GI LI
CMPEF[*] VN 0042 2 GF FV
0043 LF FV
VV 0044 GF GF
0045 LF LF
0046 GF LF
ADDTSF[*] VN 0078 2 GF FV
0079 LF FV
VV 007A GF GF
007B LF LF
007C LF GF
007D GF LF
SUBTSF[*] VN 007E 2 GF FV
007F LF FV
VV 0080 GF GF
0081 LF LF
0082 LF GF
0083 GF LF
CVFI[*] VV 008C 2 GI GF
008E LI GF
0090 GI LF
0092 LI LF
CVIF[*] VV 008D 2 GF GI
008F LF GI
0091 GF LI
0093 LF LI
ABSI 0094 1 GI
0095 LI
ABSF 0096 1 GF
0097 LF
GOTO_IF_FALSE[*] 004D 1 IV
TERMINATE_THIS_SCRIPT 004E 0
MISSION_END
START_NEW_SCRIPT[*] 004F 1 IV _ _ _
GOSUB 0050 1 IV
RETURN 0051 0
COMPARING_RULE[*] 00D6 1 IV
START_TEST_SCRIPT[*] 00D7 1 IV
GTA III Vice City San Andreas
LAUNCH_MISSION 0417 1 IV
GTA III Vice City Liberty City Stories
GOTO_IF_TRUE[*] 004C 1 IV
RETURN_TRUE[*] 00C5 0
RETURN_FALSE[*] 00C6 0
GTA III Vice City
LAUNCH_GOSUB[*] 02CD 2 IV IV
Vice City San Andreas
MOVC[*] VN 04AE 2 GC CV
04AF LC CV
CMPGC[*] VN 04B0 2 GC CV
04B1 LC CV
NV 04B2 CV GC
04B3 CV LC
CMPGEC[*] VN 04B4 2 GC CV
04B5 LC CV
NV 04B6 CV GV
04B7 CV LC
CMPEC[*] VN 04A3 2 GC CV
04A4 LC CV
San Andreas
MOVS[*] VN 05A9 2 GS SV
05AA LS SV
VV 05A9 GS GS
05AA LS LS
05A9 GS LS
05AA LS GS
MOVN[*] VN 06D1 2 GN NV
06D2 LN NV
VV 06D1 GN GN
06D2 LN LN
06D1 GN LN
06D2 LN GN
CMPES[*]
COMPARE_STRING
VN 05AD 2 GS SV
05AE LS SV
VV 05AD GS GS
05AE LS LS
05AD GS LS
05AE LS GS
CMPEN[*]
COMPARE_STRING
VN 08F9 2 GN NV
08FA LN NV
VV 08F9 GN GN
08FA LN LN
08F9 GN LN
08FA LN GN
CMPEI[*] VV 07D6 2 LI GI
CMPEF[*] VV 07D7 2 LF GF
SAVE_STRING_TO_DEBUG_FILE[*][*] 05B6 0
IS_STRING_NULL 0844 1 GS
0845 LS
0846 GN
0847 LN
INIT_TABLE_OF_GOTO[*] 0871 18 GI IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV
LI IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV
APPEND_GOTO_TO_TABLE[*] 0872 18 IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV
IS_BIT_SET VN 08B4 2 GI IV
08B7 LI IV
VV 08B5 GI GI
08B6 GI LI
08B8 LI GI
08B9 LI LI
SET_BIT VN 08BA 2 GI IV
08BD LI IV
VV 08BB GI GI
08BC GI LI
08BE LI GI
08BF LI LI
CLEAR_BIT VN 08C0 2 GI IV
08C3 LI IV
VV 08C1 GI GI
08C2 GI LI
08C4 LI GI
08C5 LI LI
STRING_STRING 098B 3 GS GS GS
098C GN GN GN
Liberty City Stories
MOVC[*] VN 04B3 2 GC CV
04B4 LC CV
CMPGC[*] VN 04B5 2 GC CV
04B6 LC CV
NV 04B7 2 CV GC
04B8 CV LC
CMPGEC[*] VN 04B9 2 GC CV
04BA LC CV
NV 04BB 2 CV GV
04BC CV LC
CMPEC[*] VN 04A8 2 GC CV
04A9 LC CV
COMPARING_RULE[*] 00DB 1 IV
START_TEST_SCRIPT[*] 00DC 1 IV
LAUNCH_GOSUB[*] 02D2 2 IV IV
LAUNCH_MISSION 041C 1 IV
CALL_FUNCTION[*][*] 05AE 4 IV IV IV IV _ _ _
05AF
Vice City Stories
MOVI[*] VN 0004 2 GI IV
LI IV
VV 0035 GI GI
LI LI
GI LI
LI GI
MOVF[*] VN 0005 2 GF FV
LF FV
VV 0036 GF GF
LF LF
GF LF
LF GF
MOVS[*] VN 0006 2 GS SV
LS SV
VV 0037 GS GS
LS LS
GS LS
LS GS
ADDI[*] VN 0007 2 GI IV
LI IV
VV 0029 GI GI
LI LI
GI LI
LI GI
ADDF[*] VN 0008 2 GF FV
LF FV
VV 002A GF GF
LF LF
GF LF
LF GF
SUBI[*] VN 0009 2 GI IV
LI IV
VV 002B GI GI
LI LI
GI LI
LI GI
SUBF[*] VN 000A 2 GF FV
LF FV
VV 002C GF GF
LF LF
GF LF
LF GF
MULI[*] VN 000B 2 GI IV
LI IV
VV 002D GI GI
LI LI
GI LI
LI GI
MULF[*] VN 000C 2 GF FV
LF FV
VV 002E GF GF
LF LF
GF LF
LF GF
DIVI[*] VN 000D 2 GI IV
LI IV
VV 002F GI GI
LI LI
GI LI
LI GI
DIVF[*] VN 000E 2 GF FV
LF FV
VV 0030 GF GF
LF LF
GF LF
LF GF
CVFI[*] VV 0038 2 GI GI
LI LI
GI LI
LI GI
CVIF[*] VV 0039 2 GF GF
LF LF
GF LF
LF GF
CMPGI[*] VN 000F 2 GI IV
LI IV
NV 0010 IV GI
IV LI
VV 0011 GI GI
LI LI
GI LI
LI GI
CMPGF[*] VN 0012 2 GF FV
LF FV
NV 0013 FV GF
FV LF
VV 0014 GF GF
LF LF
GF LF
LF GF
CMPGEI[*] VN 0015 2 GI IV
LI IV
NV 0016 IV GI
IV LI
VV 0017 GI GI
LI LI
GI LI
LI GI
CMPGEF[*] VN 0018 2 GF FV
LF FV
NV 0019 FV GF
FV LF
NV 001A GF GF
LF LF
GF LF
LF GF
CMPEI[*] VN 001B 2 GI IV
LI IV
VV 001C GI GI
LI LI
GI LI
LI GI
CMPEF[*] VN 001D 2 GF FV
LF FV
VV 001E GF GF
LF LF
GF LF
LF GF
CMPES[*]
COMPARE_STRING
VN 001F 2 GS SV
LS SV
VV 0020 GS GS
LS LS
GS LS
LS GS
ADDTSF[*] VN 0031 2 GF FV
LF FV
VV 0032 GF GF
LF LF
GF LF
LF GF
SUBTSF[*] VN 0033 2 GF FV
LF FV
VV 0034 GF GF
LF LF
GF LF
LF GF
ABSI 003A 1 GI
LI
ABSF 003B 1 GF
LF
MOVC[*] VN 02E2 2 GC CV
LC CV
CMPGC[*] VN 02E3 2 GC CV
LC CV
NV 02E4 CV GC
CV LC
CMPGEC[*] VN 02E5 2 GC CV
LC CV
NV 02E6 CV GV
CV LC
CMPEC[*] VN 02DB 2 GC CV
LC CV
GOTO_IF_TRUE[*] 0021 1 IV
GOTO_IF_FALSE[*] 0022 1 IV
TERMINATE_THIS_SCRIPT 0023 0
MISSION_END
START_NEW_SCRIPT[*] 0024 1 IV _ _ _
GOSUB 0025 1 IV
RETURN 0026 0
RETURN_TRUE[*] 005E 0
RETURN_FALSE[*] 005F 0
COMPARING_RULE[*] 0078 1 IV
START_TEST_SCRIPT[*] 0079 1 IV
LAUNCH_GOSUB[*] 01BA 2 IV IV
LAUNCH_MISSION 0289 1 IV
CALL_FUNCTION[*][*] 037A 4 IV IV IV IV _ _ _
037B
Notes
^ A special mission directive which is never compiled.
^ It is hidden when used to build statements.
^ It is never used cause it is explicitly transformed in an operator.
^ It is used only to build statements.
^ It has an undefined amount of arguments.
^ It is a likely definition of the standard command.
^ The command still accepts an argument which can admit up to 127 characters plus the null-terminator. In the compiling process, the argument is skipped but its string is copied to a predefined 128-bytes buffer, compiled afterwards. These are the predetermined bytes that seem to do nothing:
00 00 41 00 09 2E 00 00 00 00 00 00 00 00 00 00 
09 2E 00 00 00 00 00 00 1C FB 12 00 D8 A8 41 00
00 00 41 00 09 2E 00 00 00 00 00 00 01 00 00 00 
09 2E 00 00 00 00 00 00 1C FB 12 00 D8 A8 41 00
00 00 41 00 09 2E 00 00 00 00 00 00 02 00 00 00 
09 2E 00 00 00 00 00 00 1C FB 12 00 D8 A8 41 00
00 00 41 00 09 2E 00 00 00 00 00 00 03 00 00 00 
09 2E 00 00 00 00 00 00 1C FB 12 00 D8 A8 41 00
Dynamic values within a block are marked in grey, while those which differs among each block are coloured in blue.
^ Arguments vary when compiling.

This section is incomplete. You can help by fixing and expanding it.

Uncommon

Arguments of some commands keep uncommon values which look familiar after encoding:

Command Arg ID Syntax Encoded
Value Type
GTA III Vice City San Andreas Liberty City Stories Vice City Stories
GOTO 1 Any label Offset INT
GOTO_IF_FALSE 1 Any label Offset INT
GOSUB 1 Gosub label Offset INT
LAUNCH_GOSUB 1 Gosub label 0-based offset INT
2 Gosub file
START_NEW_SCRIPT 1 Script label 0-based offset INT
START_TEST_SCRIPT 1 Script file 0-based offset INT
LAUNCH_MISSION 1 Mission file Mission ID INT
GTA III Vice City Liberty City Stories Vice City Stories
GOTO_IF_TRUE 1 Any label Offset INT
Liberty City Stories Vice City Stories
CALL_FUNCTION 1 Function label Function arguments INT
2 Returning arguments
3 Parent script locals
4 Offset
San Andreas
SAVE_STRING_TO_DEBUG_FILE 1 Literal string 128-byte immediate string STRING

This section is incomplete. You can help by fixing and expanding it.

Comparing rule

The comparing rule can handle up to 9 checks per construct. 006D (GTA III, Vice City, San Andreas), 00DB (Liberty City Stories) and 0078 (Vice City Stories indicate you are verifying a single check (0) or multiple checks with either AND (1 to 8) or OR (21 to 28) logical operators.

Analysis

As an overview of the compiled source, statements are literally nested meaning that the code is unoptimized. Furthermore, the jump of an embedded construct doesn't get merged with that of the construct itself, which consists of a benefit for the code parsing.

IF

As regards the IF statement, if the whole check is true the consequence is performed and the code jumps to the end of the construct, otherwise it skips to the alternative (see also Comparing rule):

Decompiled GTA III Vice City San Andreas Liberty City Stories Vice City Stories Compiled
IF [NOT] {condition0}
[AND|OR [NOT] {condition8}]
    {consequence}
[ELSE
    {alternative}]
ENDIF
{006D}
{....}
{....}
{004D}
{....}
{0002}
 ---- 
{....}
 ---- 
{00DB}
{....}
{....}
{004D}
{....}
{0002}
 ---- 
{....}
 ---- 
{0078}
{....}
{....}
{0022}
{....}
{0002}
 ---- 
{....}
 ---- 
COMPARING_RULE {value}
    [NOT] {condition0}
    [[NOT] {condition8}]
GOTO_IF_FALSE ELSE
    {consequence}
    [GOTO ENDIF
ELSE:
    {alternative}]
ENDIF:

WHILE

The WHILE statement is pretty much similar to the previous, even though when the consequence is read the code is moved to the beginning of the construct:

Decompiled GTA III Vice City San Andreas Liberty City Stories Vice City Stories Compiled
WHILE [NOT] {condition0}
[AND|OR [NOT] {condition8}]
    {consequence}
ENDWHILE
 ---- 
{006D}
{....}
{....}
{004D}
{....}
{0002}
 ---- 
 ---- 
{00DB}
{....}
{....}
{004D}
{....}
{0002}
 ---- 
 ---- 
{0078}
{....}
{....}
{0022}
{....}
{0002}
 ---- 
WHILE:
COMPARING_RULE {value}
    [NOT] {condition0}
    [[NOT] {condition8}]
GOTO_IF_FALSE ENDWHILE
    {consequence}
    GOTO WHILE
ENDWHILE:

DO-WHILE

Not that much to say more than the preceding construct, the DO-WHILE statement is built nearly in the same way. In fact, the ELSE clause points to the end of the construct, the GOTO jumps to the its beginning, while the consequence is put before all conditions. Judging by its compiled code, it is the most certain definition that R* has originally used like the indisputable one of IF and WHILE constructs. However, a colliding issue with the WHILE statement can happen:

Decompiled Vice City San Andreas Liberty City Stories Vice City Stories Compiled
DO
    {consequence}
WHILE [NOT] {condition0}
[AND|OR [NOT] {condition8}]
 ---- 
{....}
{006D}
{....}
{....}
{004D}
{0002}
 ---- 
 ---- 
{....}
{00DB}
{....}
{....}
{004D}
{0002}
 ---- 
 ---- 
{....}
{0078}
{....}
{....}
{0022}
{0002}
 ---- 
DO:
{consequence}
COMPARING_RULE {value}
    [NOT] {condition0}
    [[NOT] {condition8}]
GOTO_IF_FALSE WHILE
    GOTO DO
WHILE:

FOR

Seemingly, the FOR statement is the first construct ever optimized as a result of a possible R*'s compiler fault. Moreover, it sounds ambiguous as it loops at least once. This was probably the intention of R*'s programmers, that is iterating at least once else the construct is useless. However, there are some chance they decide to use such structure to avoid some conflict with the WHILE or DO-WHILE construct:

Decompiled G/L San Andreas Liberty City Stories G/L Vice City Stories Compiled
FOR {varname} FROM {value0} TO {valueN}
    {consequence}
ENDFOR
{0004}
 ---- 
{....}
{0008}
{0028}
{004D}
{0005}
 ---- 
{....}
{0009}
{0029}
{004D}
{0004}
 ---- 
{....}
{0007}
{0015}
{0022}
{varname} = {value0}
LOOP:
{consequence}
++ {varname}
    {varname} >= {valueN}
GOTO_IF_FALSE LOOP

CASE

In San Andreas, the CASE statement is more complex and efficient because the game uses internally a binary search algorithm to jump at the label that matches with the value of a particular case. This method requires a known amount of cases which is up to 75. When a case is true, a consequence is executed and the code jumps to the end of the construct, otherwise the alternative may be performed. As the code is unoptimized, the GOTO of the last case is still compiled even though its label points to the end of the jump itself:

Decompiled San Andreas Compiled
CASE {varname}
    WHEN {value0}
        {consequence}
    [WHEN {valueN}
        {consequence}]
    [ELSE
        {alternative}]
ENDCASE
{0871}
{0872}
 ---- 
{....}
{0002}
 ---- 
{....}
{0002}
 ---- 
{....}
{0002}
 ---- 
{varname} {cases} {iselse} ELSE {value0} WHEN0 {valueN} WHENN -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE
[-1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE -1 ENDCASE]
WHEN0:
    {consequence}
    GOTO ENDCASE
[WHENN:
    {consequence}
    GOTO ENDCASE]
[ELSE:
    {alternative}
    GOTO ENDCASE]
ENDCASE:

In Liberty City Stories and Vice City Stories, such statement is a set of nested IF constructs which causes a very slight loss of performance by considering that 00DB (Liberty City Stories) and 0078 (Vice City Stories aren't compiled:

Decompiled G/L Liberty City Stories G/L Vice City Stories Compiled
CASE {varname}
    WHEN {value0}
        {consequence}
    [WHEN {valueN}
        {consequence}]
    [ELSE
        {alternative}]
ENDCASE
 ---- 
{0038}
{004D}
{....}
{0002}
 ---- 
{0038}
{004D}
{....}
{0002}
 ---- 
{....}
 ---- 
 ---- 
 ---- 
{0039}
{004D}
{....}
{0002}
 ---- 
{0039}
{004D}
{....}
{0002}
 ---- 
{....}
 ---- 
 ---- 
 ---- 
{001B}
{0022}
{....}
{0002}
 ---- 
{001B}
{0022}
{....}
{0002}
 ---- 
{....}
 ---- 
 ---- 
WHEN0:
    {varname} = {value0}
GOTO_IF_FALSE WHENN
    {consequence}
    [GOTO ENDCASE0
WHENN:
        {varname} = {valueN}
    GOTO_IF_FALSE ELSE
        {consequence}
        [GOTO ENDCASEN
    ELSE:
        {alternative}]
    ENDCASEN:]
ENDCASE0:

Optimization

In Liberty City Stories and Vice City Stories, whenever a single condition is checked 00DB (Liberty City Stories) and 0078 (Vice City Stories) don't get compiled cause no logical operator (AND, OR) is used and so they become really useless. Its lack increase the script efficiency a lot. However, the jump of the ELSE clause of an IF statement which points to the end of the construct is still compiled after a GOTO. Furthermore, Stories Games come with an improved data type managing which causes a considerable decrease of the compiled file size.

External links