Make control register functions const.

Author: thejpster

cortex-m/src/register/control.rs

@@ -9,19 +9,19 @@ pub struct Control {
 impl Control {
     /// Creates a `Control` value from raw bits.
     #[inline]
-    pub fn from_bits(bits: u32) -> Self {
+    pub const fn from_bits(bits: u32) -> Self {
         Self { bits }
     }
 
     /// Returns the contents of the register as raw bits
     #[inline]
-    pub fn bits(self) -> u32 {
+    pub const fn bits(self) -> u32 {
         self.bits
     }
 
     /// Thread mode privilege level
     #[inline]
-    pub fn npriv(self) -> Npriv {
+    pub const fn npriv(self) -> Npriv {
         if self.bits & (1 << 0) == (1 << 0) {
             Npriv::Unprivileged
         } else {
@@ -31,7 +31,7 @@ impl Control {
 
     /// Sets the thread mode privilege level value (nPRIV).
     #[inline]
-    pub fn set_npriv(&mut self, npriv: Npriv) {
+    pub const fn set_npriv(&mut self, npriv: Npriv) {
         let mask = 1 << 0;
         match npriv {
             Npriv::Unprivileged => self.bits |= mask,
@@ -41,7 +41,7 @@ impl Control {
 
     /// Currently active stack pointer
     #[inline]
-    pub fn spsel(self) -> Spsel {
+    pub const fn spsel(self) -> Spsel {
         if self.bits & (1 << 1) == (1 << 1) {
             Spsel::Psp
         } else {
@@ -51,7 +51,7 @@ impl Control {
 
     /// Sets the SPSEL value.
     #[inline]
-    pub fn set_spsel(&mut self, spsel: Spsel) {
+    pub const fn set_spsel(&mut self, spsel: Spsel) {
         let mask = 1 << 1;
         match spsel {
             Spsel::Psp => self.bits |= mask,
@@ -61,7 +61,7 @@ impl Control {
 
     /// Whether context floating-point is currently active
     #[inline]
-    pub fn fpca(self) -> Fpca {
+    pub const fn fpca(self) -> Fpca {
         if self.bits & (1 << 2) == (1 << 2) {
             Fpca::Active
         } else {
@@ -71,7 +71,7 @@ impl Control {
 
     /// Sets the FPCA value.
     #[inline]
-    pub fn set_fpca(&mut self, fpca: Fpca) {
+    pub const fn set_fpca(&mut self, fpca: Fpca) {
         let mask = 1 << 2;
         match fpca {
             Fpca::Active => self.bits |= mask,
@@ -92,14 +92,17 @@ pub enum Npriv {
 impl Npriv {
     /// Is in privileged thread mode?
     #[inline]
-    pub fn is_privileged(self) -> bool {
-        self == Npriv::Privileged
+    pub const fn is_privileged(self) -> bool {
+        match self {
+            Npriv::Privileged => true,
+            Npriv::Unprivileged => false,
+        }
     }
 
     /// Is in unprivileged thread mode?
     #[inline]
-    pub fn is_unprivileged(self) -> bool {
-        self == Npriv::Unprivileged
+    pub const fn is_unprivileged(self) -> bool {
+        !self.is_privileged()
     }
 }
 
@@ -115,14 +118,17 @@ pub enum Spsel {
 impl Spsel {
     /// Is MSP the current stack pointer?
     #[inline]
-    pub fn is_msp(self) -> bool {
-        self == Spsel::Msp
+    pub const fn is_msp(self) -> bool {
+        match self {
+            Spsel::Msp => true,
+            Spsel::Psp => false,
+        }
     }
 
     /// Is PSP the current stack pointer?
     #[inline]
-    pub fn is_psp(self) -> bool {
-        self == Spsel::Psp
+    pub const fn is_psp(self) -> bool {
+        !self.is_msp()
     }
 }
 
@@ -138,14 +144,17 @@ pub enum Fpca {
 impl Fpca {
     /// Is a floating-point context active?
     #[inline]
-    pub fn is_active(self) -> bool {
-        self == Fpca::Active
+    pub const fn is_active(self) -> bool {
+        match self {
+            Fpca::Active => true,
+            Fpca::NotActive => false,
+        }
     }
 
     /// Is a floating-point context not active?
     #[inline]
-    pub fn is_not_active(self) -> bool {
-        self == Fpca::NotActive
+    pub const fn is_not_active(self) -> bool {
+        !self.is_active()
     }
 }