# [−] [src] Struct wasmi::MemoryRef

    pub struct MemoryRef(_);

Reference to a memory (See `MemoryInstance` for details).

This reference has a reference-counting semantics.

## Methods from Deref<Target = MemoryInstance>

#### `pub fn initial(&self) -> Pages` [src]

Returns number of pages this `MemoryInstance` was created with.

#### `pub fn maximum(&self) -> Option<Pages>` [src]

Returns maximum amount of pages this `MemoryInstance` can grow to.

Returns `None` if there is no limit set. Maximum memory size cannot exceed `65536` pages or 4GiB.

#### `pub fn current_size(&self) -> Pages` [src]

Returns current linear memory size.

Maximum memory size cannot exceed `65536` pages or 4GiB.

# Example

To convert number of pages to number of bytes you can use the following code:

    use wasmi::MemoryInstance;
    use wasmi::memory_units::*;

    let memory = MemoryInstance::alloc(Pages(1), None).unwrap();
    let byte_size: Bytes = memory.current_size().into();
    assert_eq!(
        byte_size,
        Bytes(65536),
    );

#### `pub fn get_value<T: LittleEndianConvert>(&self, offset: u32) -> Result<T, Error>` [src]

Get value from memory at given offset.

#### `pub fn get(&self, offset: u32, size: usize) -> Result<Vec<u8>, Error>` [src]

Copy data from memory at given offset.

This will allocate vector for you. If you can provide a mutable slice you can use `get_into`.

#### `pub fn get_into(&self, offset: u32, target: &mut [u8]) -> Result<(), Error>` [src]

Copy data from given offset in the memory into `target` slice.

# Errors

Returns `Err` if the specified region is out of bounds.

#### `pub fn set(&self, offset: u32, value: &[u8]) -> Result<(), Error>` [src]

Copy data in the memory at given offset.

#### `pub fn set_value<T: LittleEndianConvert>(
&self,
offset: u32,
value: T
) -> Result<(), Error>` [src]

Copy value in the memory at given offset.

#### `pub fn grow(&self, additional: Pages) -> Result<Pages, Error>` [src]

Increases the size of the linear memory by given number of pages. Returns previous memory size if succeeds.

# Errors

Returns `Err` if attempted to allocate more memory than permited by the limit.

#### `pub fn copy(
&self,
src_offset: usize,
dst_offset: usize,
len: usize
) -> Result<(), Error>` [src]

Copy contents of one memory region to another.

Semantically equivalent to `memmove`.

# Errors

Returns `Err` if either of specified regions is out of bounds.

#### `pub fn copy_nonoverlapping(
&self,
src_offset: usize,
dst_offset: usize,
len: usize
) -> Result<(), Error>` [src]

Copy contents of one memory region to another (non-overlapping version).

Semantically equivalent to `memcpy`. but returns Error if source overlaping with destination.

# Errors

Returns `Err` if:

- either of specified regions is out of bounds,
- these regions overlaps.

#### `pub fn clear(&self, offset: usize, new_val: u8, len: usize) -> Result<(), Error>` [src]

Fill the memory region with the specified value.

Semantically equivalent to `memset`.

# Errors

Returns `Err` if the specified region is out of bounds.

#### `pub fn zero(&self, offset: usize, len: usize) -> Result<(), Error>` [src]

Fill the specified memory region with zeroes.

# Errors

Returns `Err` if the specified region is out of bounds.

#### `pub fn erase(&self) -> Result<(), Error>` [src]

Set every byte in the entire linear memory to 0, preserving its size.

Might be useful for some optimization shenanigans.

#### `pub fn with_direct_access<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R` [src]

Provides direct access to the underlying memory buffer.

# Panics

Any call that requires write access to memory (such as `set`, `clear`, etc) made within the closure will panic.

#### `pub fn with_direct_access_mut<R, F: FnOnce(&mut [u8]) -> R>(&self, f: F) -> R` [src]

Provides direct mutable access to the underlying memory buffer.

# Panics

Any calls that requires either read or write access to memory (such as `get`, `set`, [`copy`], etc) made within the closure will panic. Proceed with caution.

## Trait Implementations

### `impl Clone for MemoryRef` [src]

#### `fn clone(&self) -> MemoryRef` [src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Debug for MemoryRef` [src]

#### `fn fmt(&self, f: &mut Formatter) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl Deref for MemoryRef` [src]

#### `type Target = MemoryInstance`

The resulting type after dereferencing.

#### `fn deref(&self) -> &MemoryInstance` [src]

Dereferences the value.

## Auto Trait Implementations

### `impl !Send for MemoryRef`

### `impl !Sync for MemoryRef`

### `impl Unpin for MemoryRef`

### `impl !UnwindSafe for MemoryRef`

### `impl !RefUnwindSafe for MemoryRef`

## Blanket Implementations

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(self) -> U` [src]

Performs the conversion.

### `impl<T> From<T> for T` [src]

#### `fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `fn to_owned(&self) -> T` [src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)` [src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

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