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//! mtvec register
use crate::result::{Error, Result};
const MASK: usize = usize::MAX;
const TRAP_MASK: usize = 0b11;
read_write_csr! {
/// mtvec register
Mtvec: 0x305,
mask: MASK,
}
csr_field_enum! {
/// Trap mode
TrapMode {
default: Direct,
Direct = 0,
Vectored = 1,
}
}
read_write_csr_field! {
Mtvec,
/// Accesses the trap-vector mode.
trap_mode,
TrapMode: [0:1],
}
impl Mtvec {
/// Creates a new `Mtvec` with the given address and trap mode.
///
/// # Note
///
/// Panics if the address is not aligned to 4-bytes.
#[inline]
pub fn new(address: usize, trap_mode: TrapMode) -> Self {
Self::try_new(address, trap_mode).unwrap()
}
/// Attempts to create a new `Mtvec` with the given address and trap mode.
#[inline]
pub fn try_new(address: usize, trap_mode: TrapMode) -> Result<Self> {
let mut mtvec = Self::from_bits(0);
mtvec.try_set_address(address)?;
mtvec.set_trap_mode(trap_mode);
Ok(mtvec)
}
/// Returns the trap-vector base-address
#[inline]
pub const fn address(&self) -> usize {
self.bits & !TRAP_MASK
}
/// Sets the trap-vector base-address.
///
/// # Note
///
/// Panics if the address is not aligned to 4-bytes.
#[inline]
pub fn set_address(&mut self, address: usize) {
self.try_set_address(address).unwrap();
}
/// Attempts to set the trap-vector base-address.
///
/// # Note
///
/// Returns an error if the address is not aligned to 4-bytes.
#[inline]
pub fn try_set_address(&mut self, address: usize) -> Result<()> {
// check for four-byte alignment
if (address & TRAP_MASK) != 0 {
Err(Error::InvalidFieldVariant {
field: "mtvec::address",
value: address,
})
} else {
self.bits = address | (self.bits & TRAP_MASK);
Ok(())
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_mtvec() {
let mut m = Mtvec::from_bits(0);
(1..=usize::BITS)
.map(|r| (((1u128 << r) - 1) as usize) & !TRAP_MASK)
.for_each(|address| {
m.set_address(address);
assert_eq!(m.address(), address);
assert_eq!(m.try_set_address(address), Ok(()));
assert_eq!(m.address(), address);
});
(1..=usize::BITS)
.filter_map(|r| match ((1u128 << r) - 1) as usize {
addr if (addr & TRAP_MASK) != 0 => Some(addr),
_ => None,
})
.for_each(|address| {
assert_eq!(
m.try_set_address(address),
Err(Error::InvalidFieldVariant {
field: "mtvec::address",
value: address,
})
);
});
test_csr_field!(m, trap_mode: TrapMode::Direct);
test_csr_field!(m, trap_mode: TrapMode::Vectored);
}
}