fixup: recommended changes for register::pmpcfgx

Author: rmsyn

riscv/src/register/pmpcfgx.rs

@@ -84,50 +84,27 @@ pub struct Pmpcsr {
 
 impl Pmpcsr {
     /// Take the register contents and translate into a Pmp configuration struct
+    ///
+    /// **WARNING**: panics on:
+    ///
+    /// - non-`riscv` targets
+    /// - `index` is out of bounds
+    /// - register fields contain invalid values
     #[inline]
     pub fn into_config(&self, index: usize) -> Pmp {
-        #[cfg(riscv32)]
-        assert!(index < 4);
-
-        #[cfg(riscv64)]
-        assert!(index < 8);
-
-        let byte = (self.bits >> (8 * index)) as u8; // move config to LSB and drop the rest
-        let permission = byte & 0x7; // bits 0-2
-        let range = (byte >> 3) & 0x3; // bits 3-4
-        Pmp {
-            byte,
-            permission: match permission {
-                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 range {
-                0 => Range::OFF,
-                1 => Range::TOR,
-                2 => Range::NA4,
-                3 => Range::NAPOT,
-                _ => unreachable!(),
-            },
-            locked: (byte & (1 << 7)) != 0,
-        }
+        self.try_into_config(index).unwrap()
     }
 
     /// Attempts to take the register contents, and translate into a Pmp configuration struct.
     #[inline]
     pub fn try_into_config(&self, index: usize) -> Result<Pmp> {
-        let max = if cfg!(riscv32) {
-            Ok(4usize)
-        } else if cfg!(riscv64) {
-            Ok(8usize)
-        } else {
-            Err(Error::Unimplemented)
+        let max = match () {
+            #[cfg(riscv32)]
+            () => Ok(4usize),
+            #[cfg(riscv64)]
+            () => Ok(8usize),
+            #[cfg(not(any(riscv32, riscv64)))]
+            () => Err(Error::Unimplemented),
         }?;
 
         if index < max {