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/// Physical memory protection configuration
use bit_field::BitField;

/// Permission enum contains all possible permission modes for pmp registers
#[derive(Clone, Copy, Debug)]
pub enum Permission {
    NONE = 0b000,
    R = 0b001,
    W = 0b010,
    RW = 0b011,
    X = 0b100,
    RX = 0b101,
    WX = 0b110,
    RWX = 0b111,
}

/// Range enum contains all possible addressing modes for pmp registers
#[derive(Clone, Copy, Debug)]
pub enum Range {
    OFF = 0b00,
    TOR = 0b01,
    NA4 = 0b10,
    NAPOT = 0b11,
}

/// Pmp struct holds a high-level representation of a single pmp configuration
#[derive(Clone, Copy, Debug)]
pub struct Pmp {
    /// raw bits
    pub byte: u8,
    /// Current PMP Permission
    pub permission: Permission,
    /// Current PMP Range
    pub range: Range,
    /// Is PMP locked?
    pub locked: bool,
}

pub struct Pmpcsr {
    /// Holds the raw contents of a PMP CSR Register
    pub bits: usize,
}

impl Pmpcsr {
    /// Take the register contents and translate into a Pmp configuration struct
    #[inline]
    pub fn into_config(&self, index: usize) -> Pmp {
        #[cfg(riscv32)]
        assert!(index < 4);

        #[cfg(riscv64)]
        assert!(index < 8);

        let byte = self.bits.get_bits(8 * index..=8 * index + 7) as u8;
        Pmp {
            byte,
            permission: match byte.get_bits(0..=2) {
                0 => Permission::NONE,
                1 => Permission::R,
                2 => Permission::W,
                3 => Permission::RW,
                4 => Permission::X,
                5 => Permission::RX,
                6 => Permission::WX,
                7 => Permission::RWX,
                _ => unreachable!(),
            },
            range: match byte.get_bits(3..=4) {
                0 => Range::OFF,
                1 => Range::TOR,
                2 => Range::NA4,
                3 => Range::NAPOT,
                _ => unreachable!(),
            },
            locked: byte.get_bit(7) as bool,
        }
    }
}

/// Physical memory protection configuration
/// pmpcfg0 struct contains pmp0cfg - pmp3cfg for RV32, and pmp0cfg - pmp7cfg for RV64
pub mod pmpcfg0 {
    use super::{Permission, Pmpcsr, Range};
    use bit_field::BitField;

    read_csr_as!(Pmpcsr, 0x3A0);
    write_csr_as_usize!(0x3A0);

    set_pmp!();
    clear_pmp!();
}

/// Physical memory protection configuration
/// pmpcfg1 struct contains pmp4cfg - pmp7cfg for RV32 only
#[cfg(riscv32)]
pub mod pmpcfg1 {
    use super::{Permission, Pmpcsr, Range};
    use bit_field::BitField;

    read_csr_as!(Pmpcsr, 0x3A1);
    write_csr_as_usize_rv32!(0x3A1);

    set_pmp!();
    clear_pmp!();
}

/// Physical memory protection configuration
/// pmpcfg2 struct contains pmp8cfg - pmp11cfg for RV32, or pmp8cfg - pmp15cfg for RV64
pub mod pmpcfg2 {
    use super::{Permission, Pmpcsr, Range};
    use bit_field::BitField;

    read_csr_as!(Pmpcsr, 0x3A2);
    write_csr_as_usize!(0x3A2);

    set_pmp!();
    clear_pmp!();
}

/// Physical memory protection configuration
/// pmpcfg3 struct contains pmp12cfg - pmp15cfg for RV32 only
#[cfg(riscv32)]
pub mod pmpcfg3 {
    use super::{Permission, Pmpcsr, Range};
    use bit_field::BitField;

    read_csr_as!(Pmpcsr, 0x3A3);
    write_csr_as_usize_rv32!(0x3A3);

    set_pmp!();
    clear_pmp!();
}