[−][src]Trait flize::Tag

pub trait Tag: Copy {
    type Size: ArrayLength<bool>;
    pub fn deserialize(bits: GenericArray<bool, Self::Size>) -> Self;

    pub fn serialize(self) -> GenericArray<bool, Self::Size>;
}

The Tag trait represents any struct that can be serialized and packed into the unused bits of a pointer producing a so called "tagged" pointer. The amount of bits available are variable and the amount you can use depends on whether the tag is in in the low or high position.

In low position you can use as many bits as must be zero due to alignment. If you don't know the alignment of your pointer you can assume it is that of the value it is pointing to. The amount of available bits in the low position is the binary logarithm of the alignment in bytes.

In high position the number of available bits is determined by your compilation target. On 32 bit architectures this number shall be assumed to be equal to 0. On x86_64 with 4 level paging the number of available bits is 16 and with level 5 paging it is 8 bits. On 64 bit ARM without pointer authentication you also have 16 available bits. With pointer authentication you can only reasonably assume you have 0 available bits unless you know otherwise for your compiler. On all other architectures assume you have 0 available bits unless you know otherwise.

Associated Types

type Size: ArrayLength<bool>[src]

The size in bits of the tag.

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Required methods

pub fn deserialize(bits: GenericArray<bool, Self::Size>) -> Self[src]

Deserialize an array of bits into the tag.

pub fn serialize(self) -> GenericArray<bool, Self::Size>[src]

Serialize the tag to an array of bits.

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Implementors

impl Tag for NullTag[src]

type Size = UTerm

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