multiboot2: TagType impls Ord + renamed module

This commit renamed the module header to tag_type because this better fits. This is not visible to the public API. The enum TagType implements Ord now which enables the usage of the type in BTreeSet.

multiboot2/src/elf_sections.rs

@@ -1,4 +1,4 @@
-use crate::header::Tag;
+use crate::tag_type::Tag;
 use core::fmt::{Debug, Formatter};
 
 /// This tag contains section header table from an ELF kernel.

multiboot2/src/framebuffer.rs

@@ -1,4 +1,4 @@
-use crate::header::Tag;
+use crate::tag_type::Tag;
 use crate::Reader;
 use core::slice;
 

multiboot2/src/lib.rs

@@ -45,9 +45,6 @@ pub use elf_sections::{
     ElfSection, ElfSectionFlags, ElfSectionIter, ElfSectionType, ElfSectionsTag,
 };
 pub use framebuffer::{FramebufferColor, FramebufferField, FramebufferTag, FramebufferType};
-pub use header::TagType;
-pub use header::MULTIBOOT2_BOOTLOADER_MAGIC;
-use header::{Tag, TagIter};
 pub use image_load_addr::ImageLoadPhysAddr;
 pub use memory_map::{
     EFIMemoryAreaType, EFIMemoryDesc, EFIMemoryMapTag, MemoryArea, MemoryAreaIter, MemoryAreaType,
@@ -55,6 +52,8 @@ pub use memory_map::{
 };
 pub use module::{ModuleIter, ModuleTag};
 pub use rsdp::{RsdpV1Tag, RsdpV2Tag};
+pub use tag_type::TagType;
+use tag_type::{Tag, TagIter};
 pub use vbe_info::{
     VBECapabilities, VBEControlInfo, VBEDirectColorAttributes, VBEField, VBEInfoTag,
     VBEMemoryModel, VBEModeAttributes, VBEModeInfo, VBEWindowAttributes,
@@ -68,13 +67,22 @@ mod command_line;
 mod efi;
 mod elf_sections;
 mod framebuffer;
-mod header;
 mod image_load_addr;
 mod memory_map;
 mod module;
 mod rsdp;
+mod tag_type;
 mod vbe_info;
 
+/// Magic number that a multiboot2-compliant boot loader will store in `eax` register
+/// right before handoff to the payload (the kernel). This value can be used to check,
+/// that the kernel was indeed booted via multiboot2.
+///
+/// Caution: You might need some assembly code (e.g. GAS or NASM) first, which
+/// moves `eax` to another register, like `edi`. Otherwise it probably happens,
+/// that the Rust compiler output changes `eax` before you can access it.
+pub const MULTIBOOT2_BOOTLOADER_MAGIC: u32 = 0x36d76289;
+
 /// Load the multiboot boot information struct from an address.
 ///
 /// This is the same as `load_with_offset` but the offset is omitted and set

multiboot2/src/module.rs

@@ -1,4 +1,4 @@
-use crate::header::{Tag, TagIter, TagType};
+use crate::tag_type::{Tag, TagIter, TagType};
 use core::fmt::{Debug, Formatter};
 
 /// This tag indicates to the kernel what boot module was loaded along with

multiboot2/src/header.rs → multiboot2/src/tag_type.rs

@@ -1,21 +1,14 @@
+//! Module for [`TagType`].
+
 use core::fmt::{Debug, Formatter};
-use core::hash::{Hash, Hasher};
+use core::hash::Hash;
 use core::marker::PhantomData;
 
-/// Magic number that a multiboot2-compliant boot loader will store in `eax` register
-/// right before handoff to the payload (the kernel). This value can be used to check,
-/// that the kernel was indeed booted via multiboot2.
-///
-/// Caution: You might need some assembly code (e.g. GAS or NASM) first, which
-/// moves `eax` to another register, like `edi`. Otherwise it probably happens,
-/// that the Rust compiler output changes `eax` before you can access it.
-pub const MULTIBOOT2_BOOTLOADER_MAGIC: u32 = 0x36d76289;
-
 /// Possible types of a Tag in the Multiboot2 Information Structure (MBI), therefore the value
 /// of the the `typ` property. The names and values are taken from the example C code
 /// at the bottom of the Multiboot2 specification.
 #[repr(u32)]
-#[derive(Copy, Clone, Debug, Eq)]
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialOrd, PartialEq, Hash)]
 pub enum TagType {
     /// Marks the end of the tags.
     End = 0,
@@ -110,19 +103,6 @@ impl PartialEq<TagType> for u32 {
     }
 }
 
-impl PartialEq<TagType> for TagType {
-    fn eq(&self, other: &TagType) -> bool {
-        *self as u32 == *other as u32
-    }
-}
-
-// impl required because this type is used in a hashmap in `multiboot2-header`
-impl Hash for TagType {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        state.write_u32(*self as u32);
-    }
-}
-
 /// All tags that could passed via the Multiboot2 information structure to a payload/program/kernel.
 /// Better not confuse this with the Multiboot2 header tags. They are something different.
 #[derive(Clone, Copy)]
@@ -185,14 +165,36 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test_hash() {
-        let mut hashset = std::collections::HashSet::new();
-        hashset.insert(TagType::Cmdline);
-        hashset.insert(TagType::ElfSections);
-        hashset.insert(TagType::BootLoaderName);
-        hashset.insert(TagType::LoadBaseAddr);
-        hashset.insert(TagType::LoadBaseAddr);
-        assert_eq!(hashset.len(), 4);
-        println!("{:#?}", hashset);
+    fn test_hashset() {
+        let mut set = std::collections::HashSet::new();
+        set.insert(TagType::Cmdline);
+        set.insert(TagType::ElfSections);
+        set.insert(TagType::BootLoaderName);
+        set.insert(TagType::LoadBaseAddr);
+        set.insert(TagType::LoadBaseAddr);
+        assert_eq!(set.len(), 4);
+        println!("{:#?}", set);
+    }
+
+    #[test]
+    fn test_btreeset() {
+        let mut set = std::collections::BTreeSet::new();
+        set.insert(TagType::Cmdline);
+        set.insert(TagType::ElfSections);
+        set.insert(TagType::BootLoaderName);
+        set.insert(TagType::LoadBaseAddr);
+        set.insert(TagType::LoadBaseAddr);
+        assert_eq!(set.len(), 4);
+        for (current, next) in set.iter().zip(set.iter().skip(1)) {
+            assert!(current < next);
+        }
+        println!("{:#?}", set);
+    }
+
+    /// Tests for equality when one type is u32 and the other the enum representation.
+    #[test]
+    fn test_partial_eq_u32() {
+        assert_eq!(21, TagType::LoadBaseAddr);
+        assert_eq!(TagType::LoadBaseAddr, 21);
     }
 }