nrf-hal-common 0.18.0

//! HAL interface to the RNG peripheral.
//!
//! See nRF52832 product specification, chapter 26.

use rand_core::{CryptoRng, RngCore};

#[cfg(not(feature = "5340-net"))]
use crate::pac::RNG;
#[cfg(feature = "5340-net")]
use crate::pac::RNG_NS as RNG;

/// Interface to the RNG peripheral.
///
/// Right now, this is very basic, only providing blocking interfaces.
pub struct Rng(RNG);

impl Rng {
    pub fn new(rng: RNG) -> Self {
        rng.config.write(|w| w.dercen().enabled());
        Self(rng)
    }

    /// Fill the provided buffer with random bytes.
    ///
    /// Will block until the buffer is full.
    pub fn random(&mut self, buf: &mut [u8]) {
        self.0.tasks_start.write(|w| unsafe { w.bits(1) });

        for b in buf {
            // Wait for random byte to become ready, reset the flag once it is.
            while self.0.events_valrdy.read().bits() == 0 {}
            self.0.events_valrdy.write(|w| unsafe { w.bits(0) });

            *b = self.0.value.read().value().bits();
        }

        self.0.tasks_stop.write(|w| unsafe { w.bits(1) });
    }

    /// Return a random `u8`.
    pub fn random_u8(&mut self) -> u8 {
        let mut buf = [0; 1];
        self.random(&mut buf);
        buf[0]
    }

    /// Return a random `u16`.
    pub fn random_u16(&mut self) -> u16 {
        let mut buf = [0; 2];
        self.random(&mut buf);
        buf[0] as u16 | (buf[1] as u16) << 8
    }

    /// Return a random `u32`.
    pub fn random_u32(&mut self) -> u32 {
        let mut buf = [0; 4];
        self.random(&mut buf);
        buf[0] as u32 | (buf[1] as u32) << 8 | (buf[2] as u32) << 16 | (buf[3] as u32) << 24
    }

    /// Return a random `u64`.
    pub fn random_u64(&mut self) -> u64 {
        let mut buf = [0; 8];
        self.random(&mut buf);
        buf[0] as u64
            | (buf[1] as u64) << 8
            | (buf[2] as u64) << 16
            | (buf[3] as u64) << 24
            | (buf[4] as u64) << 32
            | (buf[5] as u64) << 40
            | (buf[6] as u64) << 48
            | (buf[7] as u64) << 56
    }
}

impl RngCore for Rng {
    fn next_u32(&mut self) -> u32 {
        self.random_u32()
    }

    fn next_u64(&mut self) -> u64 {
        self.random_u64()
    }

    fn fill_bytes(&mut self, dest: &mut [u8]) {
        self.random(dest)
    }

    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core::Error> {
        self.fill_bytes(dest);
        Ok(())
    }
}

impl CryptoRng for Rng {}