Struct VirtQueue

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pub struct VirtQueue<'a> {
    pub desc: &'a mut [Descriptor],
    pub avail: AvailableRing<'a>,
    pub used: UsedRing<'a>,
    pub free_descriptors: Vec<usize>,
    pub last_used_idx: usize,
}

Expand description

VirtQueue structure

This structure represents the wrapper of the virtqueue. It contains the descriptor table, available ring, and used ring.

§Fields

index: The ID of the virtqueue.
desc: A mutable slice of descriptors.
avail: The available ring.
used: The used ring.
free_head: The index of the next free descriptor.
last_used_idx: The index of the last used descriptor.

Fields§

§desc: &'a mut [Descriptor]§avail: AvailableRing<'a>§used: UsedRing<'a>§free_descriptors: Vec<usize>§last_used_idx: usize

Implementations§

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impl<'a> VirtQueue<'a>

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pub fn new(queue_size: usize) -> Self

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pub fn init(&mut self)

Initialize the virtqueue

This function initializes the descriptor table, available ring, and used ring. It sets the next pointer of each descriptor to point to the next descriptor in the table.

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pub fn get_raw_ptr(&self) -> *const u8

Get the raw pointer to the virtqueue

This function returns a raw pointer to the start of the virtqueue memory. It can be used to access the memory directly.

§Returns

*const u8: A raw pointer to the start of the virtqueue memory.

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pub fn get_raw_size(&self) -> usize

Get the size of the raw virtqueue

This function returns the size of the virtqueue in bytes. It is calculated as the sum of the sizes of the descriptor table, available ring, and used ring.

§Returns

usize: The size of the virtqueue in bytes.

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pub fn alloc_desc(&mut self) -> Option<usize>

Allocate a descriptor

This function allocates a descriptor from the free list.

§Returns

Option: The index of the allocated descriptor, or None if no descriptors are available.

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pub fn free_desc(&mut self, desc_idx: usize)

Free a descriptor

This function frees a descriptor and adds it back to the free list.

§Arguments

desc_idx - The index of the descriptor to free.

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pub fn alloc_desc_chain(&mut self, length: usize) -> Option<usize>

Allocate a chain of descriptors

This function allocates a chain of descriptors of the specified length.

§Arguments

length - The length of the chain to allocate.

§Returns

Option: The index of the first descriptor in the chain, or None if no descriptors are available.

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pub fn free_desc_chain(&mut self, desc_idx: usize)

Free a chain of descriptors

This function frees a chain of descriptors starting from the given index.

§Arguments

desc_idx - The index of the first descriptor in the chain.

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pub fn is_busy(&self) -> bool

Check if the virtqueue is busy

This function checks if the virtqueue is busy by comparing the last used index with the current index.

§Returns

bool: True if the virtqueue is busy, false otherwise.

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pub fn push(&mut self, desc_idx: usize) -> Result<(), &'static str>

Push a descriptor index to the available ring

This function pushes a descriptor index to the available ring.

§Arguments

desc_idx - The index of the descriptor to push. If you want to push a chain of descriptors, you should pass the first descriptor index.

§Returns

Result<(), &’static str>: Ok if the push was successful, or an error message if it failed.

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pub fn pop(&mut self) -> Option<usize>

Pop a buffer from the used ring

This function retrieves a buffer from the used ring when the device has finished processing it. The caller is responsible for freeing the descriptor when it’s done with the buffer.