wasmtime::Memory Class Reference

A WebAssembly linear memory. More...

#include <memory.hh>

Public Member Functions
	Memory (wasmtime_memory_t memory)
	Creates a new memory from the raw underlying C API representation.
MemoryType	type (Store::Context cx) const
	Returns the type of this memory.
uint64_t	size (Store::Context cx) const
	Returns the size, in WebAssembly pages, of this memory.
Span< uint8_t >	data (Store::Context cx) const
Result< uint64_t >	grow (Store::Context cx, uint64_t delta) const
uint64_t	page_size (Store::Context cx) const
uint8_t	page_size_log2 (Store::Context cx) const
const wasmtime_memory_t &	capi () const
	Returns the raw underlying C API memory this is using.

Static Public Member Functions
static Result< Memory >	create (Store::Context cx, const MemoryType &ty)
	Creates a new host-defined memory with the type specified.

Friends
class	Instance

Detailed Description

A WebAssembly linear memory.

This class represents a WebAssembly memory, either created through instantiating a module or a host memory.

Note that this type does not itself own any resources. It points to resources owned within a Store and the Store must be passed in as the first argument to the functions defined on Table. Note that if the wrong Store is passed in then the process will be aborted.

Member Function Documentation

data()

Span< uint8_t > wasmtime::Memory::data ( Store::Context  cx ) const

inline

Returns a span of where this memory is located in the host.

Note that embedders need to be very careful in their usage of the returned span. It can be invalidated with calls to grow and/or calls into WebAssembly.

grow()

Result< uint64_t > wasmtime::Memory::grow ( Store::Context  cx, uint64_t  delta  ) const

inline

Grows the memory by delta WebAssembly pages.

On success returns the previous size of this memory in units of WebAssembly pages.

page_size()

uint64_t wasmtime::Memory::page_size ( Store::Context  cx ) const

inline

Returns the size of a page, in bytes, for this memory.

WebAssembly memories are made up of a whole number of pages, so the byte size will always be a multiple of their page size. Different Wasm memories may have different page sizes.

By default this is 64KiB (aka 0x10000, 2**16, 1<<16, or 65536) but the custom-page-sizes proposal allows opting into a page size of 1. Future extensions might allow any power of two as a page size.

page_size_log2()

uint8_t wasmtime::Memory::page_size_log2 ( Store::Context  cx ) const

inline

Returns the log2 of this memory's page size, in bytes.

WebAssembly memories are made up of a whole number of pages, so the byte size will always be a multiple of their page size. Different Wasm memories may have different page sizes.

By default the page size is 64KiB (aka 0x10000, 2**16, 1<<16, or 65536) but the custom-page-sizes proposal allows opting into a page size of 1. Future extensions might allow any power of two as a page size.

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The documentation for this class was generated from the following file:

• memory.hh