riscv-aia 0.0.0

Low level access to the RISC-V Advanced Interrupt Architecture (AIA)
Documentation 
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//! Supervisor top external interrupt (only with an IMSIC) (stopei)

use crate::Iid;

riscv::read_only_csr! {
    /// Supervisor top external interrupt register.
    Stopei: 0x15C,
    mask: 0x0FFF_00FF,
}

impl Stopei {
    /// Get the major identity number of the highest-priority external interrupt.
    #[inline]
    pub const fn iid(self) -> Option<Iid> {
        let bits = (self.bits & 0x0FFF_0000) >> 16;
        Iid::new(bits as u16)
    }

    /// Indicates the priority number of the highest-priority external interrupt.
    #[inline]
    pub const fn iprio(self) -> u8 {
        (self.bits & 0x0000_00FF) as u8
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn stopei_parsing() {
        let iid_num: u16 = 2047; // max allowed
        let iprio: u8 = 0xFF;
        let bits: usize = ((iid_num as usize) << 16) | (iprio as usize);
        let reg = Stopei::from_bits(bits);
        assert_eq!(reg.iprio(), iprio);
        assert_eq!(reg.iid().map(|i| i.number()), Some(iid_num));
    }
}