Add Revision constants and constify Revision methods

Add constants for all the EFI versions (from section 4.3 "EFI System
Table"). Also make the new/major/minor methods of Revision const.

Author: nicholasbishop

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## uefi - [Unreleased]
 
+### Added
+
+- Added EFI revision constants to `Revision`.
+
 ## uefi-macros - [Unreleased]
 
 ## uefi-services - [Unreleased]
@@ -32,6 +36,7 @@
 - `DevicePath` is now a DST that represents an entire device path. The
   `DevicePathInstance` and `DevicePathNode` provide views of path
   instances and nodes, respectively.
+- The methods of `Revision` are now `const`.
 
 ### Fixed
 

src/table/revision.rs

@@ -9,21 +9,41 @@ use core::fmt;
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub struct Revision(u32);
 
+// Allow missing docs, there's nothing useful to document about these
+// constants.
+#[allow(missing_docs)]
+impl Revision {
+    pub const EFI_1_02: Self = Self::new(1, 2);
+    pub const EFI_1_10: Self = Self::new(1, 10);
+    pub const EFI_2_00: Self = Self::new(2, 00);
+    pub const EFI_2_10: Self = Self::new(2, 10);
+    pub const EFI_2_20: Self = Self::new(2, 20);
+    pub const EFI_2_30: Self = Self::new(2, 30);
+    pub const EFI_2_31: Self = Self::new(2, 31);
+    pub const EFI_2_40: Self = Self::new(2, 40);
+    pub const EFI_2_50: Self = Self::new(2, 50);
+    pub const EFI_2_60: Self = Self::new(2, 60);
+    pub const EFI_2_70: Self = Self::new(2, 70);
+    pub const EFI_2_80: Self = Self::new(2, 80);
+    pub const EFI_2_90: Self = Self::new(2, 90);
+}
+
 impl Revision {
     /// Creates a new revision.
-    pub fn new(major: u16, minor: u16) -> Self {
-        let (major, minor) = (u32::from(major), u32::from(minor));
+    pub const fn new(major: u16, minor: u16) -> Self {
+        let major = major as u32;
+        let minor = minor as u32;
         let value = (major << 16) | minor;
         Revision(value)
     }
 
     /// Returns the major revision.
-    pub fn major(self) -> u16 {
+    pub const fn major(self) -> u16 {
         (self.0 >> 16) as u16
     }
 
     /// Returns the minor revision.
-    pub fn minor(self) -> u16 {
+    pub const fn minor(self) -> u16 {
         self.0 as u16
     }
 }
@@ -35,3 +55,18 @@ impl fmt::Debug for Revision {
         write!(f, "{}.{}.{}", major, minor / 10, minor % 10)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_revision() {
+        let rev = Revision::EFI_2_31;
+        assert_eq!(rev.major(), 2);
+        assert_eq!(rev.minor(), 31);
+        assert_eq!(rev.0, 0x0002_001f);
+
+        assert!(Revision::EFI_1_10 < Revision::EFI_2_00);
+    }
+}