> For the complete documentation index, see [llms.txt](https://docs.gamesense.biz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.gamesense.biz/api-reference/ffi.md).

# FFI

Work with typed binary buffers.

The built-in `ffi` module provides typed buffers for reading and writing binary data.

Load it using `require("ffi")`.

## ffi.buffer

`ffi.buffer(size: integer): ffi_buffer`

Allocates a buffer of `size` bytes.

```lua
local ffi = require("ffi")
local data = ffi.buffer(8)

data:set_u32(0, 256)
local value = data:get_u32(0)
```

## ffi\_buffer:size

`buffer:size(): integer`

Returns the buffer size in bytes.

## Reading and writing values

`get_*` methods read values; `set_*` methods write them. Offsets are **zero-based byte positions**.

| Type   | Read               | Write                     |
| ------ | ------------------ | ------------------------- |
| UInt8  | `:get_u8(offset)`  | `:set_u8(offset, value)`  |
| Int8   | `:get_i8(offset)`  | `:set_i8(offset, value)`  |
| UInt16 | `:get_u16(offset)` | `:set_u16(offset, value)` |
| Int16  | `:get_i16(offset)` | `:set_i16(offset, value)` |
| UInt32 | `:get_u32(offset)` | `:set_u32(offset, value)` |
| Int32  | `:get_i32(offset)` | `:set_i32(offset, value)` |
| Int64  | `:get_i64(offset)` | `:set_i64(offset, value)` |
| Float  | `:get_f32(offset)` | `:set_f32(offset, value)` |
| Double | `:get_f64(offset)` | `:set_f64(offset, value)` |

```lua
local buffer = require("ffi").buffer(8)
buffer:set_i32(0, -50)
buffer:set_f32(4, 1.25)

local count = buffer:get_i32(0)
local multiplier = buffer:get_f32(4)
```

Out-of-bounds accesses raise an error. The default maximum buffer size is **1 MiB**.

{% hint style="warning" %}
This is a restricted built-in FFI implementation, **not LuaJIT FFI**. Methods such as `ffi.cdef` and `ffi.cast` are unavailable.
{% endhint %}


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