SCM language

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 Controlled Missions. 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.

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

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 native, individually or together. In , 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. 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. 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.

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 or ped events.

Limit

It is supported since .

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

It is supported in and .

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.

Limit

It is supported in .

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 .

Operators

In general, operators help programmers to do math calculations or operations of any other kind.

Assigning

Assigning is both initializing a variable and giving any value to the variable itself or the content of another one:

{varname} = {anyvalue|varname}

Calculating

Calculating is achieved by using the most common algebric operations. Sadly, the game has only support for adding, subtracting, multiplying and dividing:

{varname} += {anyvalue|varname}
{varname} -= {anyvalue|varname}
{varname} *= {anyvalue|varname}
{varname} /= {anyvalue|varname}

Yet, you can combine assigning and calculating as follows:

{varname} = {anyvalue|varname} + {anyvalue|varname}
{varname} = {anyvalue|varname} - {anyvalue|varname}
{varname} = {anyvalue|varname} * {anyvalue|varname}
{varname} = {anyvalue|varname} / {anyvalue|varname}

String (STRING, NAME) and special (CONST) types are free from these calculations. For a better code understanding, the expression of incrementing or decrementing by a unit can be written as:

{varname} ++
{varname} --
++ {varname}
-- {varname}

The compiler doesn't care about pre-increment or post-increment. Both are translated into:

{varname} += 1
{varname} -= 1

Limit

Multiple operations per line are not allowed.

Converting

Converting means casting a variable having a particular type into another. You can convert integer to floating-point values or viceversa:

{varname} =# {varname}

Ofcourse, the left variable will contain the result of the conversion of the right one.

Comparing

Comparing is the evaluation of a boolean flag regarding the comparison between two values or variables:

{varname} = {anyvalue|varname}  // equal to
{varname} > {anyvalue|varname}  // greater than
{varname} < {anyvalue|varname}  // lesser than
{varname} >= {anyvalue|varname} // greater than or equal to
{varname} <= {anyvalue|varname} // lesser than or equal to

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

Natives

A native is a symbolic name associated to a command which executes a portion of code that specifies the operation to be performed by passing zero or more arguments. Commands 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:

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

Built-in

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

• :
  • TIMESTEP
  • TIMESTEPUNWARPED
  • ABSI
  • ABSF
• :
  • COMPARE_STRING
  • SAVE_STRING_TO_DEBUG_FILE
  • IS_BIT_SET
  • SET_BIT
  • CLEAR_BIT
  • IS_STRING_NULL
  • COMBINE_STRING

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:

jump:
GOTO jump_2

[...]

jump_2:
GOTO jump

GOSUB

---

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

Embedded

---

Embedded GOSUBS are those enclosed into a file script. If local variables are used within the subroutine, you should put it into the local scope of the calling script. When included in a module, they seem to behave like embedded scripts.

Trigger

GOSUB jump

Code

jump:
[...]
RETURN

File

---

File GOSUBS are those included into a script file singularly. It's likely GOSUB_AT_FILE loads a module that can call other embedded gosubs or scripts.

Trigger

GOSUB_AT_FILE gosub.sc

Code

// File: gosub.sc

[...]
RETURN

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 Identifiers for further information).

Others

The arguments of some natives 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
Native	X
Constant	X
Statement	X

Compiling

Structure

The source code is split up into several SC files which comprehend scripts, missions, allocating scripts and modules.

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_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 natives 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_NEW_SCRIPT_FROM_FILE 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 native) and stop its execution with MISSION_END. Although missions are file scripts, 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

Allocating scripts

---

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

Modules

---

The module has been introduced since but it was never completed. It is unused in and got removed in , but then it was fully implemented in and .

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 clause before. More conditions require the use of 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

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}
    {code}
ENDFOR

Limits

It is supported since .

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 .

The WHEN clause allows the use of integer values only.

In , values must be sorted.

Multiple cases per consequence aren't allowed.

FUNCTION

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

Decompiling

Structure

For any information about the SCM file format, read this article.

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.

Offsets

An offset is a 32-bit signed integer value which points to a location of the source code. Those of scripts and modules are absolute offsets that start from the beginning of the main script, while the ones of missions and allocating scripts are relative offsets starting from their beginning. They always take 4-bytes when they are compiled as arguments.

Variables

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

Scope
Script	0-15	0-15	0-31	0-95	0-95
Mission[*]	0-15	0-15	0-1023	0-95	0-95
Allocating script	n/a	n/a	0-31	n/a	n/a
Module	0-15	0-15	n/a	0-95	0-95
Function	n/a	n/a	n/a	0-95	0-95
Timer	16-17	16-17	32-33	10-11?	254-255

^ 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 only.

Commands

A command 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 commands is 0x7FFF, since the last bit (0x8000) is set whenever they are used as negative conditions (those with the NOT clause).

Arguments

An argument is some data given as input to a command. Normally, commands 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	Acronym	Description
IV	INT value	FV	FLOAT value	CV	CONST value	SV	STRING value	NV	NAME value	LO	Label offset
GI	Global INT	GF	Global FLOAT	GC	Global CONST	GS	Global STRING	GN	Global NAME	MN	Mission number
LI	Local INT	LF	Local FLOAT	LC	Local CONST	LS	Local STRING	LN	Local NAME	AN	Allocating script number

Native or Operator	Command	Args	Arguments
			01	02	03	04	05	06	07	08	09	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31	32
MISSION_START[*]		0
GOTO[*]	0002	1	LO
INT Operator =	0004	2	GI	IV
	0006		LI	IV
	0084		GI	GI
	0085		LI	LI
	008A		GI	LI
	008B		LI	GI
FLOAT Operator =	0005	2	GF	FV
	0007		LF	FV
	0086		GF	GF
	0087		LF	LF
	0088		GF	LF
	0089		LF	GF
INT Operator +=	0008	2	GI	IV
	000A		LI	IV
	0058		GI	GI
	005A		LI	LI
	005C		LI	GI
	005E		GI	LI
FLOAT Operator +=	0009	2	GF	FV
	000B		LF	FV
	0059		GF	GF
	005B		LF	LF
	005D		LF	GF
	005F		GF	LF
INT Operator -=	000C	2	GI	IV
	000E		LI	IV
	0060		GI	GI
	0062		LI	LI
	0064		LI	GI
	0066		GI	LI
FLOAT Operator -=	000D	2	GF	FV
	000F		LF	FV
	0061		GF	GF
	0063		LF	LF
	0065		LF	GF
	0067		GF	LF
INT Operator *=	0010	2	GI	IV
	0012		LI	IV
	0068		GI	GI
	006A		LI	LI
	006C		GI	LI
	006E		LI	GI
FLOAT Operator *=	0011	2	GF	FV
	0013		LF	FV
	0069		GF	GF
	006B		LF	LF
	006D		GF	LF
	006F		LF	GF
INT Operator /=	0014	2	GI	IV
	0016		LI	IV
	0070		GI	GI
	0072		LI	LI
	0074		GI	LI
	0076		LI	GI
FLOAT Operator /=	0015	2	GF	FV
	0017		LF	FV
	0071		GF	GF
	0073		LF	LF
	0075		GF	LF
	0077		LF	GF
INT Operator =#	008C	2	GI	GF
	008E		LI	GF
	0090		GI	LF
	0092		LI	LF
FLOAT Operator =#	008D	2	GF	GI
	008F		LF	GI
	0091		GF	LI
	0093		LF	LI
INT Conditional Operator =	0038	2	GI	IV
	0039		LI	IV
	003A		GI	GI
	003B		LI	LI
	003C		GI	LI
FLOAT Conditional Operator =	0042	2	GF	FV
	0043		LF	FV
	0044		GF	GF
	0045		LF	LF
	0046		GF	LF
INT Conditional Operator >	0018	2	GI	IV
	0019		LI	IV
	001C		GI	GI
	001D		LI	LI
	001E		GI	LI
	001F		LI	GI
FLOAT Conditional Operator >	0020	2	GF	FV
	0021		LF	FV
	0024		GF	GF
	0025		LF	LF
	0026		GF	LF
	0027		LF	GF
INT Conditional Operator <	002A	2	IV	GI
	002B		IV	LI
FLOAT Conditional Operator <	0032	2	FV	GF
	0033		FV	LF
INT Conditional Operator >=	0028	2	GI	IV
	0029		LI	IV
	002C		GI	GI
	002D		LI	LI
	002E		GI	LI
	002F		LI	GI
FLOAT Conditional Operator >=	0030	2	GF	FV
	0031		LF	FV
	0034		GF	GF
	0035		LF	LF
	0036		GF	LF
	0037		LF	GF
INT Conditional Operator <=	001A	2	IV	GI
	001B		IV	LI
FLOAT Conditional Operator <=	0022	2	FV	GF
	0023		FV	LF
TIMESTEP	0078	2	GF	FV
	0079		LF	FV
	007A		GF	GF
	007B		LF	LF
	007C		LF	GF
	007D		GF	LF
TIMESTEPUNWARPED	007E	2	GF	FV
	007F		LF	FV
	0080		GF	GF
	0081		LF	LF
	0082		LF	GF
	0083		GF	LF
ABSI	0094	1	GI
	0095		LI
ABSF	0096	1	GF
	0097		LF
Jump If False[*]	004D	1	LO
TERMINATE_THIS_SCRIPT	004E	0
MISSION_END
START_NEW_SCRIPT[*]	004F	1	LO	_ _ _
GOSUB	0050	1	LO
RETURN	0051	0
Comparing Rule[*]	00D6	1	IV
START_NEW_SCRIPT_FROM_FILE[*]	00D7	1	LO
LAUNCH_MISSION	0417	1	MN
Jump If True[*]	004C	1	LO
RETURN_TRUE[*]	00C5	0
RETURN_FALSE[*]	00C6	0
GOSUB_AT_FILE[*]	02CD	2	LO	LO
CONST Operator =	04AE	2	GC	CV
	04AF		LC	CV
CONST Conditional Operator =	04A3	2	GC	CV
	04A4		LC	CV
CONST Conditional Operator >	04B0	2	GC	CV
	04B1		LC	CV
CONST Conditional Operator <	04B6	2	CV	GV
	04B7		CV	LC
CONST Conditional Operator >=	04B4	2	GC	CV
	04B5		LC	CV
CONST Conditional Operator <=	04B2	2	CV	GC
	04B3		CV	LC
STRING Operator =	05A9	2	GS	SV
			GS	GS
			GS	LS
	05AA		LS	SV
			LS	LS
			LS	GS
NAME Operator =	06D1	2	GN	NV
			GN	GN
			GN	LN
	06D2		LN	NV
			LN	LN
			LN	GN
INT Conditional Operator =	07D6	2	LI	GI
FLOAT Conditional Operator =	07D7	2	LF	GF
STRING Conditional Operator = COMPARE_STRING	05AD	2	GS	SV
			GS	GS
			GS	LS
	05AE		LS	SV
			LS	LS
			LS	GS
NAME Conditional Operator = COMPARE_STRING	08F9	2	GN	NV
			GN	GN
			GN	LN
	08FA		LN	NV
			LN	LN
			LN	GN
SAVE_STRING_TO_DEBUG_FILE[*]	05B6	0
IS_STRING_NULL	0844	1	GS
	0845		LS
	0846		GN
	0847		LN
Initialize Table Of Jumps	0871	18	GI	IV	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO
			LI	IV	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO
Append Table Jumps	0872	18	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO	IV	LO
IS_BIT_SET	08B4	2	GI	IV
	08B5		GI	GI
	08B6		GI	LI
	08B7		LI	IV
	08B8		LI	GI
	08B9		LI	LI
SET_BIT	08BA	2	GI	IV
	08BB		GI	GI
	08BC		GI	LI
	08BD		LI	IV
	08BE		LI	GI
	08BF		LI	LI
CLEAR_BIT	08C0	2	GI	IV
	08C1		GI	GI
	08C2		GI	LI
	08C3		LI	IV
	08C4		LI	GI
	08C5		LI	LI
COMBINE_STRING[*]	098B	3	GS	GS	GS
	098C		GN	GN	GN
CONST Operator =	04B3	2	GC	CV
	04B4		LC	CV
CONST Conditional Operator =	04A8	2	GC	CV
	04A9		LC	CV
CONST Conditional Operator >	04B5	2	GC	CV
	04B6		LC	CV
CONST Conditional Operator <	04BB	2	CV	GV
	04BC		CV	LC
CONST Conditional Operator >=	04B9	2	GC	CV
	04BA		LC	CV
CONST Conditional Operator <=	04B7	2	CV	GC
	04B8		CV	LC
Comparing Rule[*]	00DB	1	IV
START_NEW_SCRIPT_FROM_FILE[*]	00DC	1	LO
GOSUB_AT_FILE[*]	02D2	2	LO	LO
LAUNCH_MISSION	041C	1	MN
Call Function[*]	05AE	4	IV	IV	IV	LO	_ _ _
	05AF
INT Operator =	0004	2	GI	IV
			LI	IV
	0035		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Operator =	0005	2	GF	FV
			LF	FV
	0036		GF	GF
			GF	LF
			LF	LF
			LF	GF
STRING Operator =	0006	2	GS	SV
			LS	SV
	0037		GS	GS
			GS	LS
			LS	LS
			LS	GS
INT Operator +=	0007	2	GI	IV
			LI	IV
	0029		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Operator +=	0008	2	GF	FV
			LF	FV
	002A		GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Operator -=	0009	2	GI	IV
			LI	IV
	002B		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Operator -=	000A	2	GF	FV
			LF	FV
	002C		GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Operator *=	000B	2	GI	IV
			LI	IV
	002D		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Operator *=	000C	2	GF	FV
			LF	FV
	002E		GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Operator /=	000D	2	GI	IV
			LI	IV
	002F		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Operator /=	000E	2	GF	FV
			LF	FV
	0030		GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Operator =#	0038	2	GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Operator =#	0039	2	GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Conditional Operator =	001B	2	GI	IV
			LI	IV
	001C		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Conditional Operator =	001D	2	GF	FV
			LF	FV
	001E		GF	GF
			GF	LF
			LF	LF
			LF	GF
STRING Conditional Operator = COMPARE_STRING	001F	2	GS	SV
			LS	SV
	0020		GS	GS
			GS	LS
			LS	LS
			LS	GS
INT Conditional Operator >	000F	2	GI	IV
			LI	IV
	0011		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Conditional Operator >	0012	2	GF	FV
			LF	FV
	0014		GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Conditional Operator <	0016	2	IV	GI
			IV	LI
FLOAT Conditional Operator <	0019	2	FV	GF
			FV	LF
INT Conditional Operator >=	0015	2	GI	IV
			LI	IV
	0017		GI	GI
			GI	LI
			LI	LI
			LI	GI
FLOAT Conditional Operator >=	0018	2	GF	FV
			LF	FV
	001A		GF	GF
			GF	LF
			LF	LF
			LF	GF
INT Conditional Operator <=	0010	2	IV	GI
			IV	LI
FLOAT Conditional Operator <=	0013	2	IV	GI
			IV	LI
TIMESTEP	0031	2	GF	FV
			LF	FV
	0032		GF	GF
			GF	LF
			LF	LF
			LF	GF
TIMESTEPUNWARPED	0033	2	GF	FV
			LF	FV
	0034		GF	GF
			GF	LF
			LF	LF
			LF	GF
ABSI	003A	1	GI
			LI
ABSF	003B	1	GF
			LF
CONST Operator =	02E2	2	GC	CV
			LC	CV
CONST Conditional Operator =	02DB	2	GC	CV
			LC	CV
CONST Conditional Operator >	02E3	2	GC	CV
			LC	CV
CONST Conditional Operator <	02E6	2	CV	GV
			CV	LC
CONST Conditional Operator >=	02E5	2	GC	CV
			LC	CV
CONST Conditional Operator <=	02E4	2	CV	GC
			CV	LC
Jump If True[*]	0021	1	LO
Jump If False[*]	0022	1	LO
TERMINATE_THIS_SCRIPT	0023	0
MISSION_END
START_NEW_SCRIPT[*]	0024	1	LO	_ _ _
GOSUB	0025	1	LO
RETURN	0026	0
RETURN_TRUE[*]	005E	0
RETURN_FALSE[*]	005F	0
Comparing Rule[*]	0078	1	IV
START_NEW_SCRIPT_FROM_FILE[*]	0079	1	LO
GOSUB_AT_FILE[*]	01BA	2	LO	LO
LAUNCH_MISSION	0289	1	MN
Call Function[*]	037A	1	IV	IV	IV	LO	_ _ _
	037B

^ A special mission directive which is never compiled.

^ It is hidden when used to build statements.

^ It is hidden in the source code.

^ It has an undefined amount of arguments.

^ It is a likely definition of the standard native.

^ The native still accepts an argument which can admit up to 128 characters. 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

^ It gets transformed when compiling.

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

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

The IF statement can handle up to 9 checks per construct. 006D (, , ), 00DB () and 0078 ( indicate you are verifying a single check (0) or multiple checks with either AND clause (1 to 8) or OR clause (21 to 28). When the consequence is performed, the code jumps to the end of the construct:

Decompiled				Compiled
IF [NOT] {condition0} [AND|OR [NOT] {condition8}] {consequence} [ELSE {alternative}] ENDIF	{006D} {....} {....} {004D} {....} {0002} ---- {....} ----	{00DB} {....} {....} {004D} {....} {0002} ---- {....} ----	{0078} {....} {....} {0022} {....} {0002} ---- {....} ----	{value} [NOT] {condition0} [[NOT] {condition8}] 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				Compiled
WHILE [NOT] {condition0} [AND|OR [NOT] {condition8}] {consequence} ENDWHILE	---- {006D} {....} {....} {004D} {....} {0002} ----	---- {00DB} {....} {....} {004D} {....} {0002} ----	---- {0078} {....} {....} {0022} {....} {0002} ----	WHILE: {value} [NOT] {condition0} [[NOT] {condition8}] ENDWHILE {consequence} GOTO WHILE ENDWHILE:

FOR

Seemingly, the FOR statement is the first construct ever optimized as a result of a possible R* 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 twise else the construct is useless. However, there are some chance they decide to use such structure to avoid some conflict with the WHILE construct:

Decompiled	G/L		G/L	Compiled
FOR {varname} FROM {value0} TO {valueN} {code} ENDFOR	{0004} ---- {....} {0008} {0028} {004D}	{0005} ---- {....} {0009} {0029} {004D}	{0004} ---- {....} {0007} {0015} {0022}	{varname} = {value0} LOOP: {code} ++ {varname} {varname} >= {valueN} LOOP

CASE

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

Decompiled	G/L		G/L	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} WHENN {consequence} [GOTO ENDCASE0 WHENN: {varname} = {valueN} ELSE {consequence} [GOTO ENDCASEN ELSE: {alternative}] ENDCASEN:] ENDCASE0:

FUNCTION

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

Optimization

In and , whenever a single condition is checked 00DB () and 0078 () 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.

External links

• SC source files (no main.sc)
• GXT source code (american.gxt)