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use core::fmt;
use core::ops::{Deref, DerefMut};
const PAGE_SIZE: u64 = 4096;
const MAX_MEMORY_MAP_SIZE: usize = 64;
/// A map of the physical memory regions of the underlying machine.
#[repr(C)]
pub struct MemoryMap {
entries: [MemoryRegion; MAX_MEMORY_MAP_SIZE],
// u64 instead of usize so that the structure layout is platform
// independent
next_entry_index: u64,
}
#[doc(hidden)]
#[allow(clippy::new_without_default)]
impl MemoryMap {
pub fn new() -> Self {
MemoryMap {
entries: [MemoryRegion::empty(); MAX_MEMORY_MAP_SIZE],
next_entry_index: 0,
}
}
pub fn add_region(&mut self, region: MemoryRegion) {
assert!(
self.next_entry_index() < MAX_MEMORY_MAP_SIZE,
"too many memory regions in memory map"
);
self.entries[self.next_entry_index()] = region;
self.next_entry_index += 1;
self.sort();
}
pub fn sort(&mut self) {
use core::cmp::Ordering;
self.entries.sort_unstable_by(|r1, r2| {
if r1.range.is_empty() {
Ordering::Greater
} else if r2.range.is_empty() {
Ordering::Less
} else {
let ordering = r1
.range
.start_frame_number
.cmp(&r2.range.start_frame_number);
if ordering == Ordering::Equal {
r1.range.end_frame_number.cmp(&r2.range.end_frame_number)
} else {
ordering
}
}
});
if let Some(first_zero_index) = self.entries.iter().position(|r| r.range.is_empty()) {
self.next_entry_index = first_zero_index as u64;
}
}
fn next_entry_index(&self) -> usize {
self.next_entry_index as usize
}
}
impl Deref for MemoryMap {
type Target = [MemoryRegion];
fn deref(&self) -> &Self::Target {
&self.entries[0..self.next_entry_index()]
}
}
impl DerefMut for MemoryMap {
fn deref_mut(&mut self) -> &mut Self::Target {
let next_index = self.next_entry_index();
&mut self.entries[0..next_index]
}
}
impl fmt::Debug for MemoryMap {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list().entries(self.iter()).finish()
}
}
/// Represents a region of physical memory.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub struct MemoryRegion {
/// The range of frames that belong to the region.
pub range: FrameRange,
/// The type of the region.
pub region_type: MemoryRegionType,
}
#[doc(hidden)]
impl MemoryRegion {
pub fn empty() -> Self {
MemoryRegion {
range: FrameRange {
start_frame_number: 0,
end_frame_number: 0,
},
region_type: MemoryRegionType::Empty,
}
}
}
/// A range of frames with an exclusive upper bound.
#[derive(Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub struct FrameRange {
/// The frame _number_ of the first 4KiB frame in the region.
///
/// To convert this frame number to a physical address, multiply it with the
/// page size (4KiB).
pub start_frame_number: u64,
/// The frame _number_ of the first 4KiB frame that does no longer belong to the region.
///
/// To convert this frame number to a physical address, multiply it with the
/// page size (4KiB).
pub end_frame_number: u64,
}
impl FrameRange {
/// Create a new FrameRange from the passed start_addr and end_addr.
///
/// The end_addr is exclusive.
pub fn new(start_addr: u64, end_addr: u64) -> Self {
let last_byte = end_addr - 1;
FrameRange {
start_frame_number: start_addr / PAGE_SIZE,
end_frame_number: (last_byte / PAGE_SIZE) + 1,
}
}
/// Returns true if the frame range contains no frames.
pub fn is_empty(&self) -> bool {
self.start_frame_number == self.end_frame_number
}
/// Returns the physical start address of the memory region.
pub fn start_addr(&self) -> u64 {
self.start_frame_number * PAGE_SIZE
}
/// Returns the physical end address of the memory region.
pub fn end_addr(&self) -> u64 {
self.end_frame_number * PAGE_SIZE
}
}
impl fmt::Debug for FrameRange {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"FrameRange({:#x}..{:#x})",
self.start_addr(),
self.end_addr()
)
}
}
/// Represents possible types for memory regions.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub enum MemoryRegionType {
/// Unused memory, can be freely used by the kernel.
Usable,
/// Memory that is already in use.
InUse,
/// Memory reserved by the hardware. Not usable.
Reserved,
/// ACPI reclaimable memory
AcpiReclaimable,
/// ACPI NVS memory
AcpiNvs,
/// Area containing bad memory
BadMemory,
/// Memory used for loading the kernel.
Kernel,
/// Memory used for the kernel stack.
KernelStack,
/// Memory used for creating page tables.
PageTable,
/// Memory used by the bootloader.
Bootloader,
/// Frame at address zero.
///
/// (shouldn't be used because it's easy to make mistakes related to null pointers)
FrameZero,
/// An empty region with size 0
Empty,
/// Memory used for storing the boot information.
BootInfo,
/// Memory used for storing the supplied package
Package,
/// Additional variant to ensure that we can add more variants in the future without
/// breaking backwards compatibility.
#[doc(hidden)]
NonExhaustive,
}
#[doc(hidden)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub struct E820MemoryRegion {
pub start_addr: u64,
pub len: u64,
pub region_type: u32,
pub acpi_extended_attributes: u32,
}
impl From<E820MemoryRegion> for MemoryRegion {
fn from(region: E820MemoryRegion) -> MemoryRegion {
let region_type = match region.region_type {
1 => MemoryRegionType::Usable,
2 => MemoryRegionType::Reserved,
3 => MemoryRegionType::AcpiReclaimable,
4 => MemoryRegionType::AcpiNvs,
5 => MemoryRegionType::BadMemory,
t => panic!("invalid region type {}", t),
};
MemoryRegion {
range: FrameRange::new(region.start_addr, region.start_addr + region.len),
region_type,
}
}
}
extern "C" {
fn _improper_ctypes_check_memory_map(_memory_map: MemoryMap);
}