1 // SPDX-License-Identifier: GPL-2.0
2 
3 //! Foreign function interface (FFI) types.
4 //!
5 //! This crate provides mapping from C primitive types to Rust ones.
6 //!
7 //! The Rust [`core`] crate provides [`core::ffi`], which maps integer types to the platform default
8 //! C ABI. The kernel does not use [`core::ffi`], so it can customise the mapping that deviates from
9 //! the platform default.
10 
11 #![no_std]
12 
13 macro_rules! alias {
14     ($($name:ident = $ty:ty;)*) => {$(
15         #[allow(non_camel_case_types, missing_docs)]
16         pub type $name = $ty;
17 
18         // Check size compatibility with `core`.
19         const _: () = assert!(
20             core::mem::size_of::<$name>() == core::mem::size_of::<core::ffi::$name>()
21         );
22     )*}
23 }
24 
25 alias! {
26     // `core::ffi::c_char` is either `i8` or `u8` depending on architecture. In the kernel, we use
27     // `-funsigned-char` so it's always mapped to `u8`.
28     c_char = u8;
29 
30     c_schar = i8;
31     c_uchar = u8;
32 
33     c_short = i16;
34     c_ushort = u16;
35 
36     c_int = i32;
37     c_uint = u32;
38 
39     // In the kernel, `intptr_t` is defined to be `long` in all platforms, so we can map the type to
40     // `isize`.
41     c_long = isize;
42     c_ulong = usize;
43 
44     c_longlong = i64;
45     c_ulonglong = u64;
46 }
47 
48 pub use core::ffi::c_void;
49