io_bluetooth 0.1.0

use std::io;
use std::os::raw::c_ulong;
use std::time::Duration;

pub mod bt;
pub mod c;

pub trait IsZero {
    fn is_zero(&self) -> bool;
}

macro_rules! impl_is_zero {
    ($($t:ident)*) => ($(impl IsZero for $t {
        fn is_zero(&self) -> bool {
            *self == 0
        }
    })*)
}

impl_is_zero! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }

pub fn cvt<I: IsZero>(i: I) -> io::Result<I> {
    if i.is_zero() {
        Err(io::Error::last_os_error())
    } else {
        Ok(i)
    }
}

pub fn dur2timeout(dur: Duration) -> c_ulong {
    // Note that a duration is a (u64, u32) (seconds, nanoseconds) pair, and the
    // timeouts in windows APIs are typically u32 milliseconds. To translate, we
    // have two pieces to take care of:
    //
    // * Nanosecond precision is rounded up
    // * Greater than u32::MAX milliseconds (50 days) is rounded up to INFINITE
    //   (never time out).
    dur.as_secs()
        .checked_mul(1000)
        .and_then(|ms| ms.checked_add((dur.subsec_nanos() as u64) / 1_000_000))
        .and_then(|ms| {
            ms.checked_add(if dur.subsec_nanos() % 1_000_000 > 0 {
                1
            } else {
                0
            })
        })
        .map(|ms| {
            if ms > <c_ulong>::max_value() as u64 {
                c::INFINITE
            } else {
                ms as c_ulong
            }
        })
        .unwrap_or(c::INFINITE)
}