ark.md

This is a "specification" of the .ark file format which is used as Noa's IR format.

Ark file parsing is implemented in ark.rs, function.rs, strings.rs, and opcode.rs.

Structure

An ark file begins with a header which is followed by a series of sections.

• Header
• Function section
• Code section
• String section

Header

The header contains the identifier for the Ark file (which is always the same), as well as metadata about the program.

Byte offset	Bytes	Name	Description
0	8	identifier	The constant bytes [116, 111, 116, 104, 101, 97, 114, 107] (totheark).
8	4	main	Function ID of the main function.

Function section

The function section specifies the functions of the program.

Byte offset	Bytes	Name	Description
0	4	functions_length	The length of the following functions in bytes.
4	*	functions	A list of functions, of which the first one begins at the current byte offset.

Function

A function specifies an executable function.

Byte offset	Bytes	Name	Description
0	4	id	The unique ID of the function.
4	4	name_index	The string index of the name of the function.
8	4	arity	The amount of parameters to the function.
12	4	locals_count	The amount of locals allocated to the function.
16	4	address	The bytecode address within the code section where the function starts.

Code section

The code section contains all the bytecode which makes up the body of each function. The bytecode is stored back-to-back with a single 0xFF (boundary) opcode separating them.

Byte offset	Bytes	Name	Description
0	4	code_length	The length of the following bytecode in bytes.
4	*	code	A list of byte-encoded opcodes.

String section

The string section contains all the constant strings of the program, like function names and string literals.

Byte offset	Bytes	Name	Description
0	4	strings_length	The length of the following strings in bytes.
4	*	strings	A list of strings, of which the first one begins at the current byte offset.

String

A string is a UTF-8 encoded constant string.

Byte offset	Bytes	Name	Description
0	4	length	The length of the string in bytes.
4	*	bytes	The bytes which make up the codepoints of the string.