riscv: add mtvec unit-tests

Adds basic unit-tests for the `mtvec` CSR.

riscv/CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Use CSR helper macros to define `mip` register
 - Use CSR helper macros to define `mstatus` register
 - Use CSR helper macros to define `mstatush` register
+- Use CSR helper macros to define `mtvec` register
 
 ## [v0.12.1] - 2024-10-20
 

riscv/src/register/mtvec.rs

@@ -42,3 +42,23 @@ impl Mtvec {
         self.bits = (address & !TRAP_MASK) | (self.bits & TRAP_MASK);
     }
 }
+
+#[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))
+            .for_each(|address| {
+                m.set_address(address);
+                assert_eq!(m.address(), address & !TRAP_MASK);
+            });
+
+        test_csr_field!(m, trap_mode: TrapMode::Direct);
+        test_csr_field!(m, trap_mode: TrapMode::Vectored);
+    }
+}