Struct vm_memory::volatile_memory::VolatileArrayRef

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pub struct VolatileArrayRef<'a, T, B = ()> { /* private fields */ }

Expand description

A memory location that supports volatile access to an array of elements of type T.

Examples

let mut v = [5u32; 1];
let v_ref = unsafe { VolatileArrayRef::new(&mut v[0] as *mut u32 as *mut u8, v.len()) };

assert_eq!(v[0], 5);
assert_eq!(v_ref.load(0), 5);
v_ref.store(0, 500);
assert_eq!(v[0], 500);

Implementations

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impl<'a, T> VolatileArrayRef<'a, T> where
T: ByteValued,

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pub unsafe fn new(addr: *mut u8, nelem: usize) -> Self

Creates a VolatileArrayRef to an array of elements of type T.

To use this safely, the caller must guarantee that the memory at addr is big enough for nelem values of type T and is available for the duration of the lifetime of the new VolatileRef. The caller must also guarantee that all other users of the given chunk of memory are using volatile accesses.

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impl<'a, T, B> VolatileArrayRef<'a, T, B> where
T: ByteValued,
B: BitmapSlice,

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pub unsafe fn with_bitmap(addr: *mut u8, nelem: usize, bitmap: B) -> Self

Creates a VolatileArrayRef to an array of elements of type T, using the provided bitmap object for dirty page tracking.

Safety

To use this safely, the caller must guarantee that the memory at addr is big enough for nelem values of type T and is available for the duration of the lifetime of the new VolatileRef. The caller must also guarantee that all other users of the given chunk of memory are using volatile accesses.

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pub fn is_empty(&self) -> bool

Returns true if this array is empty.

Examples

let v_array = unsafe { VolatileArrayRef::<u32>::new(0 as *mut _, 0) };
assert!(v_array.is_empty());

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pub fn len(&self) -> usize

Returns the number of elements in the array.

Examples

assert_eq!(v_array.len(), 1);

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pub fn element_size(&self) -> usize

Returns the size of T.

Examples

let v_ref = unsafe { VolatileArrayRef::<u32>::new(0 as *mut _, 0) };
assert_eq!(v_ref.element_size(), size_of::<u32>() as usize);

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pub fn as_ptr(&self) -> *mut u8

Returns a pointer to the underlying memory. Mutable accesses performed using the resulting pointer are not automatically accounted for by the dirty bitmap tracking functionality.

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pub fn bitmap(&self) -> &B

Borrows the inner BitmapSlice.

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pub fn to_slice(&self) -> VolatileSlice<'a, B>

Converts this to a VolatileSlice with the same size and address.

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pub fn ref_at(&self, index: usize) -> VolatileRef<'a, T, B>

Does a volatile read of the element at index.

Panics

Panics if index is less than the number of elements of the array to which &self points.

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pub fn load(&self, index: usize) -> T

Does a volatile read of the element at index.

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pub fn store(&self, index: usize, value: T)

Does a volatile write of the element at index.

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pub fn copy_to(&self, buf: &mut [T]) -> usize

Copies as many elements of type T as possible from this array to buf.

Copies self.len() or buf.len() times the size of T bytes, whichever is smaller, to buf. The copy happens from smallest to largest address in T sized chunks using volatile reads.

Examples

let mut v = [0u8; 32];
let v_ref = unsafe { VolatileArrayRef::new(&mut v[0] as *mut u8, v.len()) };

let mut buf = [5u8; 16];
v_ref.copy_to(&mut buf[..]);
for &v in &buf[..] {
    assert_eq!(v, 0);
}

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pub fn copy_to_volatile_slice<S: BitmapSlice>(&self, slice: VolatileSlice<'_, S>)

Copies as many bytes as possible from this slice to the provided slice.

The copies happen in an undefined order.

Examples

let mut v = [0u8; 32];
let v_ref = unsafe { VolatileArrayRef::<u8>::new(&mut v[0] as *mut u8, v.len()) };
let mut buf = [5u8; 16];
let v_ref2 = unsafe { VolatileArrayRef::<u8>::new(&mut buf[0] as *mut u8, buf.len()) };

v_ref.copy_to_volatile_slice(v_ref2.to_slice());
for &v in &buf[..] {
    assert_eq!(v, 0);
}

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pub fn copy_from(&self, buf: &[T])

Copies as many elements of type T as possible from buf to this slice.

Copies self.len() or buf.len() times the size of T bytes, whichever is smaller, to this slice’s memory. The copy happens from smallest to largest address in T sized chunks using volatile writes.

Examples

let mut v = [0u8; 32];
let v_ref = unsafe { VolatileArrayRef::<u8>::new(&mut v[0] as *mut u8, v.len()) };

let buf = [5u8; 64];
v_ref.copy_from(&buf[..]);
for &val in &v[..] {
    assert_eq!(5u8, val);
}