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TaggedAtomicPtr to named struct

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Janis 2025-06-17 14:45:50 +02:00
parent e590dc4509
commit dc820fc64a
1 changed files with 17 additions and 14 deletions
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31
src/praetor/mod.rs
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@ -89,7 +89,10 @@ mod util {
// anything, but generally have an alignment of 8, and can be specified to
// be aligned to `n` with `#[repr(align(n))]`.
#[repr(transparent)]
pub struct TaggedAtomicPtr<T, const BITS: usize>(AtomicPtr<()>, PhantomData<T>);
pub struct TaggedAtomicPtr<T, const BITS: usize> {
ptr: AtomicPtr<()>,
_pd: PhantomData<T>,
}
impl<T, const BITS: usize> TaggedAtomicPtr<T, BITS> {
const fn mask() -> usize {
@ -99,16 +102,16 @@ mod util {
pub fn new(ptr: *mut T, tag: usize) -> TaggedAtomicPtr<T, BITS> {
debug_assert!(core::mem::align_of::<T>().ilog2() as usize >= BITS);
let mask = Self::mask();
Self(
AtomicPtr::new(ptr.with_addr((ptr.addr() & !mask) | (tag & mask)).cast()),
PhantomData,
)
Self {
ptr: AtomicPtr::new(ptr.with_addr((ptr.addr() & !mask) | (tag & mask)).cast()),
_pd: PhantomData,
}
}
pub fn ptr(&self, order: Ordering) -> NonNull<T> {
unsafe {
NonNull::new_unchecked(
self.0
self.ptr
.load(order)
.map_addr(|addr| addr & !Self::mask())
.cast(),
@ -117,7 +120,7 @@ mod util {
}
pub fn tag(&self, order: Ordering) -> usize {
self.0.load(order).addr() & Self::mask()
self.ptr.load(order).addr() & Self::mask()
}
/// returns tag
@ -137,12 +140,12 @@ mod util {
) -> Result<*mut (), *mut ()>,
) -> Result<usize, usize> {
let mask = Self::mask();
let old_ptr = self.0.load(failure);
let old_ptr = self.ptr.load(failure);
let old = old_ptr.map_addr(|addr| (addr & !mask) | (old & mask));
let new = old_ptr.map_addr(|addr| (addr & !mask) | (new & mask));
let result = cmpxchg(&self.0, old, new, success, failure);
let result = cmpxchg(&self.ptr, old, new, success, failure);
result
.map(|ptr| ptr.addr() & mask)
@ -191,10 +194,10 @@ mod util {
let mask = Self::mask();
let ptr = ptr.cast::<()>();
loop {
let old = self.0.load(failure);
let old = self.ptr.load(failure);
let new = ptr.map_addr(|addr| (addr & !mask) | (old.addr() & mask));
if self
.0
.ptr
.compare_exchange_weak(old, new, success, failure)
.is_ok()
{
@ -206,11 +209,11 @@ mod util {
pub fn set_tag(&self, tag: usize, success: Ordering, failure: Ordering) {
let mask = Self::mask();
loop {
let ptr = self.0.load(failure);
let ptr = self.ptr.load(failure);
let new = ptr.map_addr(|addr| (addr & !mask) | (tag & mask));
if self
.0
.ptr
.compare_exchange_weak(ptr, new, success, failure)
.is_ok()
{
@ -221,7 +224,7 @@ mod util {
pub fn ptr_and_tag(&self, order: Ordering) -> (NonNull<T>, usize) {
let mask = Self::mask();
let ptr = self.0.load(order);
let ptr = self.ptr.load(order);
let tag = ptr.addr() & mask;
let ptr = ptr.map_addr(|addr| addr & !mask);
let ptr = unsafe { NonNull::new_unchecked(ptr.cast()) };