Struct Alignment 

pub struct Alignment(/* private fields */);

The alignment of a buffer.

This type is a wrapper around usize that ensures the alignment is a non-zero power of 2.

Implementations

impl Alignment

pub const MAX_UNTRUSTED: Self

Largest alignment accepted from untrusted serialized input.

This admits 64KiB page alignment, as used on some ARM systems, while bounding the extra allocation required to satisfy an alignment from untrusted input.

pub const HOST_COPY: Self

Default alignment for device-to-host buffer copies.

pub const DEFAULT_ALIGNMENT: Self

Default alignment for all buffers.

Chosen to be larger than any SIMD register (e.g. AVX-512’s 64-byte registers) so that buffers can be processed with vectorized loads/stores without alignment fixups, and to match the alignment guarantees of the CUDA allocator (256 bytes) so host buffers can be copied to/from device memory without re-alignment.

pub const MAX: Alignment

The largest valid alignment: the greatest power of 2 representable in a usize.

pub const fn new(align: usize) -> Self

Create a new alignment.

Panics

Panics if align is zero or is not a power of 2.

pub const fn none() -> Self

Create a new 1-byte alignment.

pub const fn of<T>() -> Self

Create an alignment from the alignment of a type T.

Example

use vortex_buffer::Alignment;

assert_eq!(Alignment::new(4), Alignment::of::<i32>());
assert_eq!(Alignment::new(8), Alignment::of::<i64>());
assert_eq!(Alignment::new(16), Alignment::of::<u128>());

pub const fn is_aligned_to(&self, other: Alignment) -> bool

Check if self alignment is a “larger” than other alignment.

Example

use vortex_buffer::Alignment;

let a = Alignment::new(4);
let b = Alignment::new(2);
assert!(a.is_aligned_to(b));
assert!(!b.is_aligned_to(a));

pub const fn is_offset_aligned(&self, offset: usize) -> bool

Check if the given byte offset (or length) is a multiple of this alignment.

Example

use vortex_buffer::Alignment;

let a = Alignment::new(4);
assert!(a.is_offset_aligned(8));
assert!(!a.is_offset_aligned(2));

pub fn is_ptr_aligned<T>(&self, ptr: *const T) -> bool

Check if the given pointer is aligned to this alignment.

pub fn exponent(&self) -> u8

Returns the log2 of the alignment.

pub const fn from_exponent(exponent: u8) -> Self

Create from the log2 exponent of the alignment.

Panics

Panics if 1 << exponent overflows usize. Use Self::try_from_exponent when parsing untrusted input.

pub fn try_from_exponent(exponent: u8) -> VortexResult<Self>

Create from the log2 exponent of the alignment, returning an error rather than panicking if 1 << exponent would overflow usize.

Prefer this over from_exponent when the exponent originates from untrusted input such as a serialized file, where a too-large value must not panic.

pub fn try_from_untrusted_exponent(exponent: u8) -> VortexResult<Self>

Create an alignment from an exponent in untrusted serialized input.

In addition to rejecting exponents that do not fit in usize, this rejects alignments large enough to cause an unreasonable allocation when a buffer needs to be copied to satisfy the alignment.

Methods from Deref<Target = usize>

pub const MIN: usize = 0

pub const MAX: usize

pub const BITS: u32

Trait Implementations

impl Clone for Alignment

fn clone(&self) -> Alignment

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Alignment

impl Debug for Alignment

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for Alignment

type Target = usize

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Display for Alignment

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Alignment

impl From<Alignment> for usize

fn from(value: Alignment) -> Self

Converts to this type from the input type.

impl From<Alignment> for u32

fn from(value: Alignment) -> Self

Converts to this type from the input type.

impl From<u16> for Alignment

fn from(value: u16) -> Self

Converts to this type from the input type.

impl From<usize> for Alignment

fn from(value: usize) -> Self

Converts to this type from the input type.

impl Hash for Alignment

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Alignment

fn cmp(&self, other: &Alignment) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Alignment

fn eq(&self, other: &Alignment) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for Alignment

fn partial_cmp(&self, other: &Alignment) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Alignment

impl TryFrom<u32> for Alignment

type Error = VortexError

The type returned in the event of a conversion error.

fn try_from(value: u32) -> Result<Self, Self::Error>

Performs the conversion.