#[cfg(target_os = "espidf")]

pub fn sleep(dur: Duration) {

let mut micros = dur.as_micros();

unsafe {

while micros > 0 {

let st = if micros > u32::MAX as u128 { u32::MAX } else { micros as u32 };

// ESP-IDF does not have `nanosleep`, so we use `usleep` instead.

// As per the documentation of `usleep`, it is expected to support

// sleep times as big as at least up to 1 second.

//

// ESP-IDF does support almost up to `u32::MAX`, but due to a potential integer overflow in its

// `usleep` implementation

// (https://github.com/espressif/esp-idf/blob/d7ca8b94c852052e3bc33292287ef4dd62c9eeb1/components/newlib/time.c#L210),

// we limit the sleep time to the maximum one that would not cause the underlying `usleep` implementation to overflow

// (`portTICK_PERIOD_MS` can be anything between 1 to 1000, and is 10 by default).

const MAX_MICROS: u32 = u32::MAX - 1_000_000 - 1;

// Add any nanoseconds smaller than a microsecond as an extra microsecond

// so as to comply with the `std::thread::sleep` contract which mandates

// implementations to sleep for _at least_ the provided `dur`.

// We can't overflow `micros` as it is a `u128`, while `Duration` is a pair of

// (`u64` secs, `u32` nanos), where the nanos are strictly smaller than 1 second

// (i.e. < 1_000_000_000)

let mut micros = dur.as_micros() + if dur.subsec_nanos() % 1_000 > 0 { 1 } else { 0 };

while micros > 0 {

let st = if micros > MAX_MICROS as u128 { MAX_MICROS } else { micros as u32 };

unsafe {

libc::usleep(st);

micros -= st as u128;

}

micros -= st as u128;

}

}