Class Memory

Represents a WebAssembly memory.

Inheritance

System.Object

Memory

Namespace: Wasmtime

Assembly: Wasmtime.Dotnet.dll

Syntax

public class Memory : object

Constructors

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Memory(Store, Int64, Nullable<Int64>, Boolean)

Creates a new WebAssembly memory.

Declaration

public Memory(Store store, long minimum = null, long? maximum = null, bool is64Bit = false)

Parameters

Type	Name	Description
Store	store	The store to create the memory in.
System.Int64	minimum	The minimum number of WebAssembly pages.
System.Nullable<System.Int64>	maximum	The maximum number of WebAssembly pages, or `null` to not specify a maximum.
System.Boolean	is64Bit	`true` when memory type represents a 64-bit memory, `false` when it represents a 32-bit memory.

Fields

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PageSize

The size, in bytes, of a WebAssembly memory page.

Declaration

public const int PageSize = null

Field Value

Type	Description
System.Int32

Properties

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Is64Bit

Gets a value that indicates whether this type of memory represents a 64-bit memory.

Declaration

public bool Is64Bit { get; }

Property Value

Type	Description
System.Boolean	`true` if this type of memory represents a 64-bit memory, `false` otherwise.

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Maximum

Gets the maximum memory size (in WebAssembly page units).

Declaration

public long? Maximum { get; }

Property Value

Type	Description
System.Nullable<System.Int64>	The maximum memory size (in WebAssembly page units), or `null` if no maximum is specified.

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Minimum

Gets the minimum memory size (in WebAssembly page units).

Declaration

public long Minimum { get; }

Property Value

Type	Description
System.Int64	The minimum memory size (in WebAssembly page units).

Methods

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GetLength()

Gets the current length of the memory, in bytes.

Declaration

public long GetLength()

Returns

Type	Description
System.Int64	Returns the current length of the memory, in bytes.

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GetPointer()

Returns a pointer to the start of the memory. The length for which the pointer is valid can be retrieved with GetLength().

Declaration

public IntPtr GetPointer()

Returns

Type	Description
IntPtr	Returns a pointer to the start of the memory.

Remarks

The pointer may become invalid if the memory grows.

This may happen if the memory is explicitly requested to grow or grows as a result of WebAssembly execution.

Therefore, the returned pointer should not be used after calling the grow method or after calling into WebAssembly code.

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GetSize()

Gets the current size of the memory, in WebAssembly page units.

Declaration

public long GetSize()

Returns

Type	Description
System.Int64	Returns the current size of the memory, in WebAssembly page units.

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GetSpan()

Gets the span of the memory.

Declaration

public Span<byte> GetSpan()

Returns

Type	Description
Span<System.Byte>	Returns the span of the memory.

Remarks

The span may become invalid if the memory grows.

This may happen if the memory is explicitly requested to grow or grows as a result of WebAssembly execution.

Therefore, the returned span should not be used after calling the grow method or after calling into WebAssembly code.

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GetSpan(Int64, Int32)

Gets a span of a section of the memory.

Declaration

public Span<byte> GetSpan(long address, int length)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address of the start of the span.
System.Int32	length	The length of the span.

Returns

Type	Description
Span<System.Byte>	Returns the span of a section of the memory.

Remarks

The span may become invalid if the memory grows.

This may happen if the memory is explicitly requested to grow or grows as a result of WebAssembly execution.

Therefore, the returned span should not be used after calling the grow method or after calling into WebAssembly code.

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GetSpan<T>(Int32)

Gets the span of the memory viewed as a specific type, starting at a given address.

Declaration

public Span<T> GetSpan<T>(int address)
    where T : struct

Parameters

Type	Name	Description
System.Int32	address	The zero-based address of the start of the span.

Returns

Type	Description
Span<T>	Returns the span of the memory.

Type Parameters

Name	Description
T

Remarks

The span may become invalid if the memory grows.

This may happen if the memory is explicitly requested to grow or grows as a result of WebAssembly execution.

Therefore, the returned span should not be used after calling the grow method or after calling into WebAssembly code.

Note that WebAssembly always uses little endian as byte order. On platforms that use big endian, you will need to convert numeric values accordingly.

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GetSpan<T>(Int64, Int32)

Gets a span of a section of the memory.

Declaration

public Span<T> GetSpan<T>(long address, int length)
    where T : struct

Parameters

Type	Name	Description
System.Int64	address	The zero-based address of the start of the span.
System.Int32	length	The length of the span.

Returns

Type	Description
Span<T>	Returns the span of a section of the memory.

Type Parameters

Name	Description
T

Remarks

The span may become invalid if the memory grows.

This may happen if the memory is explicitly requested to grow or grows as a result of WebAssembly execution.

Therefore, the returned span should not be used after calling the grow method or after calling into WebAssembly code.

Note that WebAssembly always uses little endian as byte order. On platforms that use big endian, you will need to convert numeric values accordingly.

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Grow(Int64)

Grows the memory by the specified number of pages.

Declaration

public long Grow(long delta)

Parameters

Type	Name	Description
System.Int64	delta	The number of WebAssembly pages to grow the memory by.

Returns

Type	Description
System.Int64	Returns the previous size of the Webassembly memory, in pages.

Remarks

This method will invalidate previously returned values from GetSpan.

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Read<T>(Int64)

Read a struct from memory.

Declaration

public T Read<T>(long address)
    where T : struct

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
T	Returns the struct read from memory.

Type Parameters

Name	Description
T	Type of the struct to read. Ensure layout in C# is identical to layout in WASM.

Remarks

Note that WebAssembly always uses little endian as byte order. On platforms that use big endian, you will need to convert numeric values accordingly.

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ReadByte(Int64)

Reads a byte from memory.

Declaration

public byte ReadByte(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.Byte	Returns the byte read from memory.

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ReadDouble(Int64)

Reads a double from memory.

Declaration

public double ReadDouble(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.Double	Returns the double read from memory.

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ReadInt16(Int64)

Reads a short from memory.

Declaration

public short ReadInt16(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.Int16	Returns the short read from memory.

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ReadInt32(Int64)

Reads an int from memory.

Declaration

public int ReadInt32(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.Int32	Returns the int read from memory.

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ReadInt64(Int64)

Reads a long from memory.

Declaration

public long ReadInt64(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.Int64	Returns the long read from memory.

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ReadIntPtr(Int64)

Reads an IntPtr from memory.

Declaration

public IntPtr ReadIntPtr(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
IntPtr	Returns the IntPtr read from memory.

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ReadNullTerminatedString(Int64)

Reads a null-terminated UTF-8 string from memory.

Declaration

public string ReadNullTerminatedString(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.String	Returns the string read from memory.

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ReadSingle(Int64)

Reads a single from memory.

Declaration

public float ReadSingle(long address)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.

Returns

Type	Description
System.Single	Returns the single read from memory.

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ReadString(Int64, Int32, Nullable<Encoding>)

Reads a string from memory with the specified encoding.

Declaration

public string ReadString(long address, int length, Encoding? encoding = null)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.
System.Int32	length	The length of bytes to read.
System.Nullable<Encoding>	encoding	The encoding to use when reading the string; if null, UTF-8 encoding is used.

Returns

Type	Description
System.String	Returns the string read from memory.

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Write<T>(Int64, T)

Write a struct to memory.

Declaration

public void Write<T>(long address, T value)
    where T : struct

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to read from.
T	value	The struct to write.

Type Parameters

Name	Description
T

Remarks

Note that WebAssembly always uses little endian as byte order. On platforms that use big endian, you will need to convert numeric values accordingly.

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WriteByte(Int64, Byte)

Writes a byte to memory.

Declaration

public void WriteByte(long address, byte value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.Byte	value	The byte to write.

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WriteDouble(Int64, Double)

Writes a double to memory.

Declaration

public void WriteDouble(long address, double value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.Double	value	The double to write.

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WriteInt16(Int64, Int16)

Writes a short to memory.

Declaration

public void WriteInt16(long address, short value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.Int16	value	The short to write.

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WriteInt32(Int64, Int32)

Writes an int to memory.

Declaration

public void WriteInt32(long address, int value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.Int32	value	The int to write.

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WriteInt64(Int64, Int64)

Writes a long to memory.

Declaration

public void WriteInt64(long address, long value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.Int64	value	The long to write.

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WriteIntPtr(Int64, IntPtr)

Writes an IntPtr to memory.

Declaration

public void WriteIntPtr(long address, IntPtr value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
IntPtr	value	The IntPtr to write.

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WriteSingle(Int64, Single)

Writes a single to memory.

Declaration

public void WriteSingle(long address, float value)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.Single	value	The single to write.

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WriteString(Int64, String, Nullable<Encoding>)

Writes a string at the given address with the given encoding.

Declaration

public int WriteString(long address, string value, Encoding? encoding = null)

Parameters

Type	Name	Description
System.Int64	address	The zero-based address to write to.
System.String	value	The string to write.
System.Nullable<Encoding>	encoding	The encoding to use when writing the string; if null, UTF-8 encoding is used.

Returns

Type	Description
System.Int32