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
13macro_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
25alias! {
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
48pub use core::ffi::c_void;