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LUA is an imperative programming language, designed in 1993 by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, and Waldemar Celes, members of the Computer Graphics Technology Group (Tecgraf) at PUC-Rio, the Pontifical University of Rio de Janeiro, in Brazil. "Lua" means "Moon" in Portuguese. Lua is used in SimCity 4 for the generation of help texts, creation of rewards, defining U-Drive-It missions, and other types of codes.

More information about Lua can be found on the official site and on Wikipedia.


Use in SimCity 4

Lua has many uses in SimCity 4, as mentioned above. The exact format used can vary depending on the use. The formats below are courtesy of Karybdis.

Instance by: CRC24Polynomial = 0x01864cfb, CRC24Seed = 0x00b704ce, return (CRC24(from, false) | 0xFF000000)

The types of LUA files are:

Binary LUA

The following format is for binary Lua scripts, and was developed by Quaxi.

Here are the first things known about the .objLua and .globalObjLua:

General Format

	DWord: 1b 4c 75 61   (ID)
	Byte: Version    
	16-Bytes: Header
	    ---> Root "Function Block"

Function Block

	Dword: Character count n
	n-Byte: Name of the Function (null terminated)
	5-Byte: unknown
	Byte: argument Count
	Byte: unknown
	Byte: stack Size
	12-Byte: 00

	4-Byte: constant counter 
	    ---> Loop Constant Block
	4-Byte: functions counter
	    ---> Loop Function Block

	4-Byte: instruction counter
	    ---> Loop Instruction Block

Instruction Block

(a=Operand a, b=Operand b, c=Operand c, o=Opcode):

	Dword: aaaa aaaa bbbb bbbb bccc cccc ccoo oooo    

This Document lists the available opcodes:

Constant Block

	Byte: ConstantType
	    ----> Constant Data

List of Known Constant Data Types

0x00 = Empty, Null -  This seems to mark an empty block
0x03 = Number
          DWord: Unknown
          DWord: Unknown
0x04 = Strings
          DWord: Length n of the following PString
          n-Bytes: Instruction Name, null-terminated

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