Wasm protocol genrator

This is a simple tool to generate a protocol for a wasm module. It generates functions for c and typst to encode and decode the protocol. The protocol is defined in a simple file format that ressembles a list of c structs.

Usage

Command	Description
-o	Output folder
-c	C code output folder, it overrides -o and requires -t
-t	Typescript code output folder, it overrides -o and requires -c
--check	Check the protocol file for errors without generating any code

Protocol file format

The protocol file format is a list of structs and protocol definitions. You can define multiple protocol in the same file and each file will generate a different set of functions.

Structs

A struct is defined like follows:

struct Name {
    ...fieds
}

Where Name is the name of the struct and fields is a list of fields separated by semicolon.

Protocol

A protocol is defined like follows:

protocol (C|Typst|Bidirectional) Name {
    ...fields
}

The langage is the target language of the protocol, if it is C, the protocol will be encoded by Typst and decoded by C. if it is Typst the protocol will be encoded by C and decoded by Typst. Bidirectional is used when you whant the protocol to be encoded and decoded by both languages.

Where Name is the name of the protocol and fields is a list of fields separated by semicolon.

Fields

A field is defined like follows:

type name;

Where type is the type of the field and name is the name of the field.

Types

The following types are supported:

Type	Description
int	32 bits signed integer
bool	a boolean
string	a c like string
char	a single character
float	32 bits floating point number
point	32 bits floating point number in point, so it will be treated as a length in point in typst and as normal float in C
Name	The type of the struct Name defined previously in the file

Any of the previous types can be put in an array by adding [] after the field name.

Example

struct Point {
    int x;
    int y;
}

This defines a struct Point with two fields x and y of type int.

protocol C Shape {
    Point points[];
    string name;
}

This defines a protocol Shape that will be encoded by Typst and decoded by C. It has two fields, points, an array of Point and name a string.

protocol Typst Area {
    float area;
    string name;
}

This defines a protocol Area that will be encoded by C and decoded by Typst. It has two fields, area, a float and name a string.

Genrated code

C

The generated C code will expose the struct and the functions to encode and decode each protocol. The struct will be the same as defined in the protocol file with the same name.

Each function name will be the name of the protocol prefixed by encode_ or decode_.

If you add an array to your protocol, the generated struct will have a field name_len that must contain the length of the array before encoding the protocol.

When you use them, you shouldn't manipulate the input buffer directly, the decode function will do it for you. The only thing you need to do is to pass the input buffer length to the decode function.

Error codes signification

Code	Description
0	No error
1	Malloc error
2	Invalid buffer length
3	Invalid protocol

Example

Based on the previous example, you will get the following exposed interface:

struct Point {
    int x;
    int y;
}

struct Shape {
    Point *points;
    int points_len;
    char *name;
}

struct Area {
    float area;
    char *name;
}

int encode_Shape(Shape *shape);
int decode_Area(size_t buffer_len, Area *area);

Typst

The generated Typst will use dictionaries to represent the protocol structures. But the naming convention is rufly the same as the C code: the functions will be prefixed by encode- or decode-.

Example

Based on the previous example, you will get the following exposed interface:

#let encode-area(value) = ...
#let decode-shape(bytes) = ...