Files
Redox-From-Scratch/bootloader/src/os/bios/memory_map.rs
2024-12-11 18:21:07 -08:00

85 lines
2.2 KiB
Rust

use core::{cmp, mem, ptr};
use crate::area_add;
use crate::os::{OsMemoryEntry, OsMemoryKind};
use super::{thunk::ThunkData, MEMORY_MAP_ADDR};
#[repr(C, packed)]
struct MemoryMapEntry {
pub base: u64,
pub size: u64,
pub kind: u32,
}
pub struct MemoryMapIter {
thunk15: extern "C" fn(),
data: ThunkData,
first: bool,
}
impl MemoryMapIter {
pub fn new(thunk15: extern "C" fn()) -> Self {
Self {
thunk15,
data: ThunkData::new(),
first: true,
}
}
}
impl Iterator for MemoryMapIter {
type Item = OsMemoryEntry;
fn next(&mut self) -> Option<Self::Item> {
if self.first {
self.first = false;
} else if self.data.ebx == 0 {
return None;
}
self.data.eax = 0xE820;
self.data.ecx = mem::size_of::<MemoryMapEntry>() as u32;
self.data.edx = 0x534D4150;
self.data.edi = MEMORY_MAP_ADDR as u32;
unsafe {
self.data.with(self.thunk15);
}
//TODO: return error?
assert_eq!({ self.data.eax }, 0x534D4150);
assert_eq!({ self.data.ecx }, mem::size_of::<MemoryMapEntry>() as u32);
let entry = unsafe { ptr::read(MEMORY_MAP_ADDR as *const MemoryMapEntry) };
Some(Self::Item {
base: entry.base,
size: entry.size,
kind: match entry.kind {
0 => OsMemoryKind::Null,
1 => OsMemoryKind::Free,
3 => OsMemoryKind::Reclaim,
_ => OsMemoryKind::Reserved,
},
})
}
}
pub unsafe fn memory_map(thunk15: extern "C" fn()) -> Option<(usize, usize)> {
let mut heap_limits = None;
for entry in MemoryMapIter::new(thunk15) {
let heap_start = 1 * 1024 * 1024;
if { entry.kind } == OsMemoryKind::Free
&& entry.base <= heap_start as u64
&& (entry.base + entry.size) >= heap_start as u64
{
let heap_end = cmp::min(entry.base + entry.size, usize::MAX as u64) as usize;
if heap_end >= heap_start {
heap_limits = Some((heap_start, heap_end - heap_start));
}
}
area_add(entry);
}
heap_limits
}