Talk:SCM language
Contents
Rework ETA?
It seems pointless to edit the page on the wiki while the rework is going on, since the reworked page will presumably completely replace the current one entirely (correct me if I am wrong on that). Is there any ETA for the rework? Additionally, would it be possible for the rework to be done entirely on the wiki – section by section maybe – so that people can actively contribute to the page during the rework? – Squ1dd13 (talk) 11:39, 3 September 2020 (UTC)
- If you are willing to help, send me a modified version of the work-in-progress article privately on GTAF. I will then pick up myself what's worth and discard the rest. – Wesser (talk) 19:37, 3 September 2020 (UTC)
- Hey. Nice to see another member of the community interested in the language after so long. Thanks for the updates. Let me express some disagreements: Command is an element of the language, opcode an element of the runtime environment (i.e. CRunningScript). The name of a operation should be command, since that is what Rockstar's miss2.exe strings call them (never mentioning something as an opcode). The language and the runtime should be treated as separate entities (e.g. Python can target CPython, PyPy, JVM, CLR and even native code) due to the separation of programming languages and compiler fields in computer science. b) Alternators shouldn't be called overloads IMO, because that's probably not how Rockstar called them. This language is quite exotic, and that's something to get used to. The leaked compiler always refer to it as an "alternative". Plus, when one describes it formally, it's not as easy to parallel it with function overloading (can talk further if necessary). Anyway, since you are here, you might be interested in something I've been working for the past few years. It's still unfinished therefore I have not yet acquired feedback from other community members, but it may provide insights onto the design of the language: https://gtamodding.github.io/gta3script-specs. It's pretty formal, but that's what it is supposed to be. Best regards. Link2012 (talk) 19:57, 28 September 2020 (UTC)
Miss2
I'm not going to update the article by myself because I'm not good with words, my english is not so good... I'm going to left informations here to fix the article... All information here is based on the reverse engineering of the SCM compiler left on Vice City 10th Anniversary, I will refer to this compiler here only by miss2 (Yeah, the name is the same as GTA 2 Script Compiler)
About the 'SCM' meaning
SCM may stand for "Script Multifile", since the button to compile a scm is named "Run MultiFile parser", we have also the button "Run Parser" that produces a .scc file, it's unknown about the usage of that .scc Somewhere in the compiler code we have something like
if(IsMultifile)
strcat(OutputFilename, "m")
else
strcat(OutputFilename, "c")
Comments
One mistake on the article about comments, the article say:
Limit Multiline comments cannot be nested.
But actually multiline comments CAN BE nested.
Round brackets
They are replaced by ' ' in the first compilation step, so probably they are really for reading or highlighting purposes. ',' is also replaced with ' '
Types
About VAR_CONST
There is not VAR_CONST, but actually 04AE (and others) are used to assign a constant value into a VAR_INT, example:
VAR_INT a a = PAD2 TERMINATE_THIS_SCRIPT
>>
04AE: $303 = 1 004E: end_thread
About SHORT STRINGS VARIABLE
The 8 byte string variable is called VAR_TEXT_LABEL
About LONG STRINGS VARIABLE
No trace about that variable type in miss2, but I can guess it was called VAR_STRING
Arrays
The article is right about how arrays are declared (VAR_INT array[size]), but we have a strange behaviour around arrays... The index seem to start from 1 instead of 0, very strange, let's see a example
VAR_INT a[4] a[0] = 0 a[1] = 1 a[2] = 2 a[3] = 3 a[4] = 4 //a[5] = 0 -- WOULD OUTPUT A ERROR ABOUT ARRAY OUT OF RANGE TERMINATE_THIS_SCRIPT
>>
0004: $303 = 0 0004: $303 = 1 0004: $304 = 2 0004: $305 = 3 0004: $306 = 4 004E: end_thread
The array support on miss2 is not good since Vice City don't have arrays, using array[var] would output a messed file, so we can't say much about it.
Operators
Time Step operator
The time step operator is not =- or =+, but +=@ or -=@, example:
VAR_FLOAT a a +=@ 1.0 a -=@ 1.0 a = 1.0 +@ 2.0 a = a -@ 3.0 TERMINATE_THIS_SCRIPT
>>
0078: $303 += time_step * 1.0 007E: $303 -= time_step * 1.0 0005: $303 = 1.0 0078: $303 += time_step * 2.0 007E: $303 -= time_step * 3.0 004E: end_thread
Compare String
No COMPARE_STRING, string comparision is done with the comparision operator (at least for VAR_TEXT_LABEL)
Constants
Constants are hardcoded (as everything in the compiler). Maybe they changed this on the SA Compiler or maybe AudioEvents.txt is a constant dump file.
The script files
File gosubs
They are called "main extension files" and "foreign gosubs" and are called using GOSUB_FILE Example:
GOSUB_FILE sub_label sub_file.sc
START_NEW_SCRIPT, LAUNCH_MISSION & LOAD_AND_LAUNCH_MISSION
START_NEW_SCRIPT is 004F, LAUNCH_MISSION is 00D7 and LOAD_AND_LAUNCH_MISSION is 0417 Okay, you may say: "Somewhere in GTA III Script files we have a commented block where LAUNCH_MISSION is launching a mission (0417)...", Yes, but this has probably been changed during the time, look again at that commented part and look the final code in sanny, the code is different.
There's also LOAD_AND_LAUNCH_MISSION_EXCLUSIVE, I don't know the purposes of it, okay.
LAUNCH_MISSION scripts are called Subscripts
The START_NEW_SCRIPT target label MUST be inside a scope block... The compiler also checks for the variables in that scope block to see if the START_NEW_SCRIPT extra params can be accept by the variables in the script scope block.
The foreign scripts MUST be inside a folder with the same name as the main script file, inside another folder or not. Example:
main.sc
main\
subscript1.sc
subscript2.sc
initial_mission.sc
mission_guy\
mission_guy1.sc
mission_guy2.sc
darkel\
darkel1.sc
darkel2.sc
darkel3.sc
Usage Example:
START_NEW_SCRIPT label 1
LAUNCH_MISSION subscript1.sc // launch a subscript
LOAD_AND_LAUNCH_MISSION darkel1.sc // launch a mission
TERMINATE_THIS_SCRIPT
{
label:
LVAR_INT number_1
TERMINATE_THIS_SCRIPT
}
Statements
There's no DO..WHILE_TRUE and probably there's no FOR..ENDFOR too But we have a new statement over here, REPEAT..ENDREPEAT
REPEAT num_times var // code here ENDREPEAT
This is like a FOR (for that reason I said there's no FOR...ENDFOR), will repeat the code num_times, using the var as the counter variable.
Example:
VAR_INT x k REPEAT 4 x k *= 10 ENDREPEAT TERMINATE_THIS_SCRIPT
>>
0004: $303 = 0 :Noname_7 0010: $304 *= 10 0008: $303 += 1 0028: $303 >= 4 004D: jump_if_false @Noname_7 004E: end_thread
128 Byte Strings
128 bytes strings are enclosed in quotation marks, example:
"128B STRING"
Models constant
They are read from the IDE files in maps folder... Actually miss2 read default.ide and gta_vc.dat, after parsing gta_vc.dat, miss2 will read all listed IDE files.
Entity Variables
miss2 doesn't permit you to assign more than one entity to a specific variable, for example:
VAR_INT var CREATE_CAR 400 0.0 0.0 0.0 var CREATE_CHAR 4 1 0.0 0.0 0.0 var // error: Variable has already been used to create a entity of a different type TERMINATE_THIS_SCRIPT
