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//!
//! C FFI - va_list support
//!
//! This crate provides an interface for rust code to read values passed in C's va_list type.
//!
//! ## Example
//! In C Code
//!
//! ```c++
//! #include <stdint.h>
//! #include <stdarg.h>
//! extern void print_ints_va(uint32_t count, va_list args);
//! extern void print_ints(uint32_t count, ...)
//! {
//!   va_list args;
//!   va_start(args, count);
//!   print_ints_va(count, args);
//!   va_end(args);
//! }
//! ```
//!
//! In rust code:
//!
//! ```rust
//! extern crate va_list;
//!
//! #[no_mangle]
//! extern "C" fn print_ints_va(count: u32, mut args: va_list::VaList)
//! {
//!   unsafe {
//!     for i in (0 .. count) {
//!       println!("{}: {}", i, args.get::<i32>());
//!     }
//!   }
//! }
//! ```
//!
#![cfg_attr(feature = "no_std", no_std)]
#![crate_type = "lib"]
#![crate_name = "va_list"]

#[cfg(feature = "no_std")]
#[doc(hidden)]
mod std {
    pub use core::{mem, ptr, ffi};
}

// x86_64 on unix platforms is _usually_ ELF.
#[cfg(all(target_arch = "x86_64",
          any(target_family = "unix", target_os = "redox", target_os = "tifflin")))]
#[path = "impl-x86_64-elf.rs"]
mod imp;

//// x86_64 on windows is special
#[cfg(all(target_arch = "x86_64", target_family = "windows"))]
#[path = "impl-x86_64-win64.rs"]
mod imp;

// x86+unix = cdecl
#[cfg(all(target_arch = "x86", target_family = "unix"))]
#[path = "impl-x86-sysv.rs"]
mod imp;

// aarch64
#[cfg(all(
    target_arch = "aarch64",
    any(target_family = "unix", target_os = "redox"),
    not(any(target_os = "macos", target_os = "ios")),
))]
#[path = "impl-aarch64-elf.rs"]
mod imp;

// arm+unix = cdecl
#[cfg(all(target_arch = "arm", target_family = "unix"))]
#[path = "impl-arm-sysv.rs"]
mod imp;

// aarch64+macos
#[cfg(all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")))]
#[path = "impl-aarch64-macos.rs"]
mod imp;

/// Rust version of C's `va_list` type from the `stdarg.h` header
#[repr(C)]
pub struct VaList {
    internal: imp::VaList,
}

/// Core type as passed though the FFI
impl VaList {
    /// Read a value from the VaList.
    ///
    /// Users should take care that they are reading the correct type
    pub unsafe fn get<T: VaPrimitive>(&mut self) -> T {
        T::get(&mut self.internal)
    }
}

/// Trait implemented on types that can be read from a va_list
pub trait VaPrimitive: 'static {
    #[doc(hidden)]
    unsafe fn get(&mut imp::VaList) -> Self;
}