south fossil
I have the following function to detect machine endianness:
fn endianness() -> Endianness {
let x = 0x10u16;
let bytes: [u8; 2] = unsafe { std::mem::transmute(x) };
match bytes {
[1, 0] => Endianness::Big,
[0, 1] => Endianness::Little
}
}
enum Endianness {
Little,
Big
}
Does this have any caveats I should be aware of?
old cosmos
Just do 1u16.to_ne_bytes() == 1u16.to_be_bytes(). Or use the compiler flag: https://doc.rust-lang.org/reference/conditional-compilation.html#target_endian
#[cfg(target_endian = "little")]
dim flare
Yeah, if your code is only worried about the target's endianness, use:```rust
#[cfg(target_endian = "big")]
{
/* Value to calculate or stuff to do on big-endian targets /
}
#[cfg(target_endian = "little")]
{
/ Value to calculate or stuff to do on little-endian targets */
}
If you're going to be dealing with endianness beyond the target's:
?play ```rust
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[repr(u8)]
pub enum Endianness {
Big,
Little,
}
pub const TARGET_ENDIANNESS: Endianness = {
#[cfg(target_endian = "big")]
{
Endianness::Big
}
#[cfg(target_endian = "little")]
{
Endianness::Little
}
};
#[inline(always)]
pub fn target_endianness() -> Endianness {
TARGET_ENDIANNESS
}
fn main() {
dbg!(target_endianness());
}
pliant epochBOT
[src/main.rs:25] target_endianness() = Little```Like if you're going to talk about the endianness of file format fields or something.
Also, remember that to_be_bytes or from_be_bytes (and le versions) exist for things that might differ from the target endianness.
worn bough
?play ```rust
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)...
do you need the const ?playrust #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] #[repr(u8)] pub enum Endianness { Big, Little, } #[inline(always)] pub fn target_endianness() -> Endianness { #[cfg(target_endian = "big")] { Endianness::Big } #[cfg(target_endian = "little")] { Endianness::Little } } fn main() { dbg!(target_endianness()); } is better no ?
dim flare
It was mainly to show the option that you can use a constant.
I'm not sure how they'd like to structure it.
dreamy girder
?play ```rust
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)...
I like how this code includes compile time protection against neither cfg beïng set
just in case someone chooses to compile for a middle-endian target, you wouldn’t want your code to be incorrect