// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Platform-independent platform abstraction
//!
//! This is the platform-independent portion of the standard libraries
//! platform abstraction layer, whereas `std::sys` is the
//! platform-specific portion.
//!
//! The relationship between `std::sys_common`, `std::sys` and the
//! rest of `std` is complex, with dependencies going in all
//! directions: `std` depending on `sys_common`, `sys_common`
//! depending on `sys`, and `sys` depending on `sys_common` and `std`.
//! Ideally `sys_common` would be split into two and the dependencies
//! between them all would form a dag, facilitating the extraction of
//! `std::sys` from the standard library.

#![allow(missing_docs)]

pub mod io;
pub mod mutex;
pub mod poison;
pub mod remutex;
pub mod thread_local;

// common error constructors

/// A trait for viewing representations from std types
#[doc(hidden)]
pub trait AsInner<Inner: ?Sized> {
    fn as_inner(&self) -> &Inner;
}

/// A trait for viewing representations from std types
#[doc(hidden)]
pub trait AsInnerMut<Inner: ?Sized> {
    fn as_inner_mut(&mut self) -> &mut Inner;
}

/// A trait for extracting representations from std types
#[doc(hidden)]
pub trait IntoInner<Inner> {
    fn into_inner(self) -> Inner;
}

/// A trait for creating std types from internal representations
#[doc(hidden)]
pub trait FromInner<Inner> {
    fn from_inner(inner: Inner) -> Self;
}

macro_rules! rtabort {
    ($($t:tt)*) => (::sys_common::util::abort(format_args!($($t)*)))
}

// Computes (value*numer)/denom without overflow, as long as both
// (numer*denom) and the overall result fit into i64 (which is the case
// for our time conversions).
#[allow(dead_code)] // not used on all platforms
pub fn mul_div_u64(value: u64, numer: u64, denom: u64) -> u64 {
    let q = value / denom;
    let r = value % denom;
    // Decompose value as (value/denom*denom + value%denom),
    // substitute into (value*numer)/denom and simplify.
    // r < denom, so (denom*numer) is the upper bound of (r*numer)
    q * numer + r * numer / denom
}

#[test]
fn test_muldiv() {
    assert_eq!(mul_div_u64( 1_000_000_000_001, 1_000_000_000, 1_000_000),
               1_000_000_000_001_000);
}