https://github.com/excessive/cdata

Serialize Lua tables to C structs and strings.
https://github.com/excessive/cdata

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Serialize Lua tables to C structs and strings.

• Host: GitHub
• URL: https://github.com/excessive/cdata
• Owner: excessive
• License: other
• Created: 2015-01-23T03:22:44.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2015-08-14T20:13:09.000Z (about 9 years ago)
• Last Synced: 2024-08-02T06:19:47.290Z (3 months ago)
• Language: Lua
• Homepage:
• Size: 129 KB
• Stars: 30
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

Awesome Lists containing this project

• awesome-love2d - cdata - Serialize between Lua data and C data using LuaJIT's FFI. (Serialization)

README

        
# C Data

C Data is a simple wrapper for LuaJIT FFI's cast to C String. This is primarily used to serialize Lua tables into network-transferable data.

It is worth noting that if you encode an incomplete table (missing a key) then when you decode the packet, it will have the missing key with a value of 0.

## Examples

### Register Packets

```lua

local cdata   = require "cdata"

local packets = {}

-- all structs get a type field so we don't lose our minds.

function add_struct(name, fields, map)

    local struct = string.format("typedef struct { uint8_t type; %s } %s;", fields, name)

    cdata:new_struct(name, struct)

    -- the packet_type struct isn't a real packet, so don't index it.

    if map then

        map.name = name

        table.insert(packets, map)

        packets[name] = #packets

    end

end

-- Slightly special, I guess.

add_struct("packet_type", "")

add_struct(

    "player_whois", [[

        uint16_t id;

    ]], {

        "id",

    }

)

add_struct(

    "player_create", [[

        uint16_t id;

        uint8_t flags;

        float position_x, position_y, position_z;

        float orientation_x, orientation_y, orientation_z;

        unsigned char name[64];

    ]], {

        "id",

        "flags",

        "position_x", "position_y", "position_z",

        "orientation_x", "orientation_y", "orientation_z",

        "name",

    }

)

add_struct(

    "player_update", [[

        uint16_t id;

        float position_x, position_y, position_z;

        float orientation_x, orientation_y, orientation_z;

    ]], {

        "id",

        "position_x", "position_y", "position_z",

        "orientation_x", "orientation_y", "orientation_z",

    }

)

add_struct(

    "player_action", [[

        uint16_t id;

        uint16_t action;

    ]], {

        "id",

        "action",

    }

)

```

### Encode Data

```lua

local player = self.players[1]

local data   = {

    type          = packets["player_update"],

    id            = player.id,

    position_x    = player.position.x,

    position_y    = player.position.y,

    position_z    = player.position.z,

    orientation_x = player.orientation.x,

    orientation_y = player.orientation.y,

    orientation_z = player.orientation.z,

}

local struct  = cdata:set_struct("player_update", data)

local encoded = cdata:encode(struct)

```

### Decode Data

```lua

-- We assume we have a variable named data that we received from the network

local header = cdata:decode("packet_type", data)

local map    = packets[header.type]

if not map then

    error(string.format("Invalid packet type (%s) received!", header.type))

    return

end

local decoded = cdata:decode(map.name, data)

```