Modules#

otLinkedBuffer

otTcpEndpoint

otTcpEndpointInitializeArgs

otTcpListener

otTcpListenerInitializeArgs

TCP#

This module includes functions that control TCP communication.

Enumerations#

enum
OT_TCP_DISCONNECTED_REASON_NORMAL
OT_TCP_DISCONNECTED_REASON_REFUSED
OT_TCP_DISCONNECTED_REASON_RESET
OT_TCP_DISCONNECTED_REASON_TIME_WAIT
OT_TCP_DISCONNECTED_REASON_TIMED_OUT
}
enum
@25 {
OT_TCP_CONNECT_NO_FAST_OPEN = 1 << 0
}

This enumeration defines flags passed to otTcpConnect().

enum
@26 {
OT_TCP_SEND_MORE_TO_COME = 1 << 0
}

This enumeration defines flags passed to otTcpSendByReference.

enum
OT_TCP_INCOMING_CONNECTION_ACTION_ACCEPT
OT_TCP_INCOMING_CONNECTION_ACTION_DEFER
OT_TCP_INCOMING_CONNECTION_ACTION_REFUSE
}

This enumeration defines incoming connection actions.

Typedefs#

typedef struct otLinkedBuffer

A linked buffer structure for use with TCP.

typedef void(*
otTcpEstablished)(otTcpEndpoint *aEndpoint)

This callback informs the application that the TCP 3-way handshake is complete and that the connection is now established.

typedef void(*
otTcpSendDone)(otTcpEndpoint *aEndpoint, otLinkedBuffer *aData)

This callback informs the application that data in the provided aData have been acknowledged by the connection peer and that aData and the data it contains can be reclaimed by the application.

typedef void(*
otTcpForwardProgress)(otTcpEndpoint *aEndpoint, size_t aInSendBuffer, size_t aBacklog)

This callback informs the application if forward progress has been made in transferring data from the send buffer to the recipient.

typedef void(*
otTcpReceiveAvailable)(otTcpEndpoint *aEndpoint, size_t aBytesAvailable, bool aEndOfStream, size_t aBytesRemaining)

This callback indicates the number of bytes available for consumption from the receive buffer.

typedef enum otTcpDisconnectedReason
typedef void(*
otTcpDisconnected)(otTcpEndpoint *aEndpoint, otTcpDisconnectedReason aReason)

This callback indicates that the connection was broken and should no longer be used, or that a connection has entered the TIME-WAIT state.

This structure contains arguments to the otTcpEndpointInitialize() function.

This enumeration defines incoming connection actions.

otTcpAcceptReady)(otTcpListener *aListener, const otSockAddr *aPeer, otTcpEndpoint **aAcceptInto)

This callback indicates that an incoming connection that matches this TCP listener has arrived.

typedef void(*
otTcpAcceptDone)(otTcpListener *aListener, otTcpEndpoint *aEndpoint, const otSockAddr *aPeer)

This callback indicates that the TCP connection is now ready for two-way communication.

This structure contains arguments to the otTcpListenerInitialize() function.

Functions#

otTcpEndpointInitialize(otInstance *aInstance, otTcpEndpoint *aEndpoint, const otTcpEndpointInitializeArgs *aArgs)

Initializes a TCP endpoint.

otTcpEndpointGetInstance(otTcpEndpoint *aEndpoint)

Obtains the otInstance that was associated with aEndpoint upon initialization.

void *
otTcpEndpointGetContext(otTcpEndpoint *aEndpoint)

Obtains the context pointer that was associated with aEndpoint upon initialization.

const otSockAddr *
otTcpGetLocalAddress(const otTcpEndpoint *aEndpoint)

Obtains a pointer to a TCP endpoint's local host and port.

const otSockAddr *
otTcpGetPeerAddress(const otTcpEndpoint *aEndpoint)

Obtains a pointer to a TCP endpoint's peer's host and port.

otTcpBind(otTcpEndpoint *aEndpoint, const otSockAddr *aSockName)

Binds the TCP endpoint to an IP address and port.

otTcpConnect(otTcpEndpoint *aEndpoint, const otSockAddr *aSockName, uint32_t aFlags)

Records the remote host and port for this connection.

otTcpSendByReference(otTcpEndpoint *aEndpoint, otLinkedBuffer *aBuffer, uint32_t aFlags)

Adds data referenced by the linked buffer pointed to by aBuffer to the send buffer.

otTcpSendByExtension(otTcpEndpoint *aEndpoint, size_t aNumBytes, uint32_t aFlags)

Adds data to the send buffer by extending the length of the final otLinkedBuffer in the send buffer by the specified amount.

otTcpReceiveByReference(otTcpEndpoint *aEndpoint, const otLinkedBuffer **aBuffer)

Provides the application with a linked buffer chain referencing data currently in the TCP receive buffer.

otTcpReceiveContiguify(otTcpEndpoint *aEndpoint)

Reorganizes the receive buffer to be entirely contiguous in memory.

otTcpCommitReceive(otTcpEndpoint *aEndpoint, size_t aNumBytes, uint32_t aFlags)

Informs the TCP stack that the application has finished processing aNumBytes bytes of data at the start of the receive buffer and that the TCP stack need not continue maintaining those bytes in the receive buffer.

otTcpSendEndOfStream(otTcpEndpoint *aEndpoint)

Informs the connection peer that this TCP endpoint will not send more data.

otTcpAbort(otTcpEndpoint *aEndpoint)

Forcibly ends the TCP connection associated with this TCP endpoint.

otTcpEndpointDeinitialize(otTcpEndpoint *aEndpoint)

Deinitializes this TCP endpoint.

otTcpListenerInitialize(otInstance *aInstance, otTcpListener *aListener, const otTcpListenerInitializeArgs *aArgs)

Initializes a TCP listener.

otTcpListenerGetInstance(otTcpListener *aListener)

Obtains the otInstance that was associated with aListener upon initialization.

void *
otTcpListenerGetContext(otTcpListener *aListener)

Obtains the context pointer that was associated with aListener upon initialization.

otTcpListen(otTcpListener *aListener, const otSockAddr *aSockName)

Causes incoming TCP connections that match the specified IP address and port to trigger this TCP listener's callbacks.

otTcpStopListening(otTcpListener *aListener)

Causes this TCP listener to stop listening for incoming connections.

otTcpListenerDeinitialize(otTcpListener *aListener)

Deinitializes this TCP listener.

Macros#

#define

OT_TCP_ENDPOINT_TCB_SIZE_BASE and OT_TCP_ENDPOINT_TCB_NUM_POINTERS are chosen such that the mTcb field of otTcpEndpoint has the same size as struct tcpcb in TCPlp.

#define

Recommended buffer size for TCP connections that traverse about 3 wireless hops or fewer.

#define

Recommended buffer size for TCP connections that traverse many wireless hops.

#define

OT_TCP_LISTENER_TCB_SIZE_BASE and OT_TCP_LISTENER_TCB_NUM_POINTERS are chosen such that the mTcbListener field of otTcpListener has the same size as struct tcpcb_listen in TCPlp.

Enumeration Documentation#

otTcpDisconnectedReason#

otTcpDisconnectedReason
Enumerator
OT_TCP_DISCONNECTED_REASON_NORMAL
OT_TCP_DISCONNECTED_REASON_REFUSED
OT_TCP_DISCONNECTED_REASON_RESET
OT_TCP_DISCONNECTED_REASON_TIME_WAIT
OT_TCP_DISCONNECTED_REASON_TIMED_OUT

Definition at line 191 of file include/openthread/tcp.h

@25#

@25

This enumeration defines flags passed to otTcpConnect().

Enumerator
OT_TCP_CONNECT_NO_FAST_OPEN

Definition at line 396 of file include/openthread/tcp.h

@26#

@26

This enumeration defines flags passed to otTcpSendByReference.

Enumerator
OT_TCP_SEND_MORE_TO_COME

Definition at line 424 of file include/openthread/tcp.h

otTcpIncomingConnectionAction#

otTcpIncomingConnectionAction

This enumeration defines incoming connection actions.

This is used in otTcpAcceptReady() callback.

Enumerator
OT_TCP_INCOMING_CONNECTION_ACTION_ACCEPT

Accept the incoming connection.

OT_TCP_INCOMING_CONNECTION_ACTION_DEFER

Defer (silently ignore) the incoming connection.

OT_TCP_INCOMING_CONNECTION_ACTION_REFUSE

Refuse the incoming connection.


Definition at line 590 of file include/openthread/tcp.h

Typedef Documentation#

otLinkedBuffer#

typedef struct otLinkedBuffer otLinkedBuffer

A linked buffer structure for use with TCP.

A single otLinkedBuffer structure references an array of bytes in memory, via mData and mLength. The mNext field is used to form a chain of otLinkedBuffer structures.


Definition at line 68 of file include/openthread/tcp.h

otTcpEndpoint#

typedef struct otTcpEndpoint otTcpEndpoint

Definition at line 71 of file include/openthread/tcp.h

otTcpEstablished#

typedef void(* otTcpEstablished) (otTcpEndpoint *aEndpoint) )(otTcpEndpoint *aEndpoint)

This callback informs the application that the TCP 3-way handshake is complete and that the connection is now established.

Parameters
[in]aEndpoint

The TCP endpoint whose connection is now established.


Definition at line 80 of file include/openthread/tcp.h

otTcpSendDone#

typedef void(* otTcpSendDone) (otTcpEndpoint *aEndpoint, otLinkedBuffer *aData) )(otTcpEndpoint *aEndpoint, otLinkedBuffer *aData)

This callback informs the application that data in the provided aData have been acknowledged by the connection peer and that aData and the data it contains can be reclaimed by the application.

Parameters
[in]aEndpoint

The TCP endpoint for the connection.

[in]aData

A pointer to the otLinkedBuffer that can be reclaimed.

The aData are guaranteed to be identical to those passed in to TCP via otTcpSendByReference(), including any extensions effected via otTcpSendByExtension().


Definition at line 95 of file include/openthread/tcp.h

otTcpForwardProgress#

typedef void(* otTcpForwardProgress) (otTcpEndpoint *aEndpoint, size_t aInSendBuffer, size_t aBacklog) )(otTcpEndpoint *aEndpoint, size_t aInSendBuffer, size_t aBacklog)

This callback informs the application if forward progress has been made in transferring data from the send buffer to the recipient.

Parameters
[in]aEndpoint

The TCP endpoint for the connection.

[in]aInSendBuffer

The number of bytes in the send buffer (sum of "in-flight" and "backlog" regions).

[in]aBacklog

The number of bytes that are queued for sending but have not yet been sent (the "backlog" region).

This callback is not necessary for correct TCP operation. Most applications can just rely on the otTcpSendDone() callback to reclaim linked buffers once the TCP stack is done using them. The purpose of this callback is to support advanced applications that benefit from finer-grained information about how the the connection is making forward progress in transferring data to the connection peer.

This callback's operation is closely tied to TCP's send buffer. The send buffer can be understood as having two regions. First, there is the "in-flight" region at the head (front) of the send buffer. It corresponds to data which has been sent to the recipient, but is not yet acknowledged. Second, there is the "backlog" region, which consists of all data in the send buffer that is not in the "in-flight" region. The "backlog" region corresponds to data that is queued for sending, but has not yet been sent.

The callback is invoked in response to two types of events. First, the "in-flight" region of the send buffer may shrink (e.g., when the recipient acknowledges data that we sent earlier). Second, the "backlog" region of the send buffer may shrink (e.g., new data was sent out). These two conditions often occur at the same time, in response to an ACK segment from the connection peer, which is why they are combined in a single callback.

The TCP stack only uses the aInSendBuffer bytes at the tail of the send buffer; when aInSendBuffer decreases by an amount x, it means that x additional bytes that were formerly at the head of the send buffer are no longer part of the send buffer and can now be reclaimed (i.e., overwritten) by the application. Note that the otLinkedBuffer structure itself can only be reclaimed once all bytes that it references are no longer part of the send buffer.

This callback subsumes otTcpSendDone(), in the following sense: applications can determine when linked buffers can be reclaimed by comparing aInSendBuffer with how many bytes are in each linked buffer. However, we expect otTcpSendDone(), which directly conveys which otLinkedBuffers can be reclaimed, to be much simpler to use. If both callbacks are registered and are triggered by the same event (e.g., the same ACK segment received), then the otTcpSendDone() callback will be triggered first, followed by this callback.

Additionally, this callback provides aBacklog, which indicates how many bytes of data in the send buffer are not yet in flight. For applications that only want to add data to the send buffer when there is an assurance that it will be sent out soon, it may be desirable to only send out data when aBacklog is suitably small (0 or close to 0). For example, an application may use aBacklog so that it can react to queue buildup by dropping or aggregating data to avoid creating a backlog of data.

After a call to otTcpSendByReference() or otTcpSendByExtension() with a positive number of bytes, the otTcpForwardProgress() callback is guaranteed to be called, to indicate when the bytes that were added to the send buffer are sent out. The call to otTcpForwardProgress() may be made immediately after the bytes are added to the send buffer (if some of those bytes are immediately sent out, reducing the backlog), or sometime in the future (once the connection sends out some or all of the data, reducing the backlog). By "immediately," we mean that the callback is immediately scheduled for execution in a tasklet; to avoid reentrancy-related complexity, the otTcpForwardProgress() callback is never directly called from the otTcpSendByReference() or otTcpSendByExtension() functions.


Definition at line 165 of file include/openthread/tcp.h

otTcpReceiveAvailable#

typedef void(* otTcpReceiveAvailable) (otTcpEndpoint *aEndpoint, size_t aBytesAvailable, bool aEndOfStream, size_t aBytesRemaining) )(otTcpEndpoint *aEndpoint, size_t aBytesAvailable, bool aEndOfStream, size_t aBytesRemaining)

This callback indicates the number of bytes available for consumption from the receive buffer.

Parameters
[in]aEndpoint

The TCP endpoint for the connection.

[in]aBytesAvailable

The number of bytes in the connection's receive buffer.

[in]aEndOfStream

Indicates if additional data, beyond what is already in the connection's receive buffer, can be received.

[in]aBytesRemaining

The number of additional bytes that can be received before the receive buffer becomes full.

It is called whenever bytes are added to the receive buffer and when the end of stream is reached. If the end of the stream has been reached (i.e., if no more data will become available to read because the connection peer has closed their end of the connection for writing), then aEndOfStream is true. Finally, aBytesRemaining indicates how much capacity is left in the receive buffer to hold additional data that arrives.


Definition at line 186 of file include/openthread/tcp.h

otTcpDisconnectedReason#

typedef enum otTcpDisconnectedReason otTcpDisconnectedReason

Definition at line 198 of file include/openthread/tcp.h

otTcpDisconnected#

typedef void(* otTcpDisconnected) (otTcpEndpoint *aEndpoint, otTcpDisconnectedReason aReason) )(otTcpEndpoint *aEndpoint, otTcpDisconnectedReason aReason)

This callback indicates that the connection was broken and should no longer be used, or that a connection has entered the TIME-WAIT state.

Parameters
[in]aEndpoint

The TCP endpoint whose connection has been lost.

[in]aReason

The reason why the connection was lost.

It can occur if a connection establishment attempt (initiated by calling otTcpConnect()) fails, or any point thereafter (e.g., if the connection times out or an RST segment is received from the connection peer). Once this callback fires, all resources that the application provided for this connection (i.e., any otLinkedBuffers and memory they reference, but not the TCP endpoint itself or space for the receive buffers) can be reclaimed. In the case of a connection entering the TIME-WAIT state, this callback is called twice, once upon entry into the TIME-WAIT state (with OT_TCP_DISCONNECTED_REASON_TIME_WAIT, and again when the TIME-WAIT state expires (with OT_TCP_DISCONNECTED_REASON_NORMAL).


Definition at line 219 of file include/openthread/tcp.h

otTcpEndpointInitializeArgs#

typedef struct otTcpEndpointInitializeArgs otTcpEndpointInitializeArgs

This structure contains arguments to the otTcpEndpointInitialize() function.


Definition at line 284 of file include/openthread/tcp.h

otTcpListener#

typedef struct otTcpListener otTcpListener

Definition at line 582 of file include/openthread/tcp.h

otTcpIncomingConnectionAction#

typedef enum otTcpIncomingConnectionAction otTcpIncomingConnectionAction

This enumeration defines incoming connection actions.

This is used in otTcpAcceptReady() callback.


Definition at line 595 of file include/openthread/tcp.h

otTcpAcceptReady#

typedef otTcpIncomingConnectionAction(* otTcpAcceptReady) (otTcpListener *aListener, const otSockAddr *aPeer, otTcpEndpoint **aAcceptInto) )(otTcpListener *aListener, const otSockAddr *aPeer, otTcpEndpoint **aAcceptInto)

This callback indicates that an incoming connection that matches this TCP listener has arrived.

Parameters
[in]aListener

The TCP listener that matches the incoming connection.

[in]aPeer

The host and port from which the incoming connection originates.

[out]aAcceptInto

The TCP endpoint into which to accept the incoming connection.

The typical response is for the application to accept the incoming connection. It does so by populating aAcceptInto with a pointer to the otTcpEndpoint into which to accept the incoming connection. This otTcpEndpoint must already be initialized using otTcpEndpointInitialize(). Then, the application returns OT_TCP_INCOMING_CONNECTION_ACTION_ACCEPT.

Alternatively, the application can decline to accept the incoming connection. There are two ways for the application to do this. First, if the application returns OT_TCP_INCOMING_CONNECTION_ACTION_DEFER, then OpenThread silently ignores the connection establishment request; the connection peer will likely retransmit the request, at which point the callback will be called again. This is valuable if resources are not presently available to accept the connection, but they may be available when the connection peer retransmits its connection establishment attempt. Second, if the application returns OT_TCP_INCOMING_CONNECTION_ACTION_REFUSE, then OpenThread sends a "connection refused" message to the host that attempted to establish a connection. If the application declines the incoming connection, it is not required to populate aAcceptInto.

Returns

  • Description of how to handle the incoming connection.


Definition at line 627 of file include/openthread/tcp.h

otTcpAcceptDone#

typedef void(* otTcpAcceptDone) (otTcpListener *aListener, otTcpEndpoint *aEndpoint, const otSockAddr *aPeer) )(otTcpListener *aListener, otTcpEndpoint *aEndpoint, const otSockAddr *aPeer)

This callback indicates that the TCP connection is now ready for two-way communication.

Parameters
[in]aListener

The TCP listener that matches the incoming connection.

[in]aEndpoint

The TCP endpoint into which the incoming connection was accepted.

[in]aPeer

the host and port from which the incoming connection originated.

In the case of TCP Fast Open, this may be before the TCP connection handshake has actually completed. The application is provided with the context pointers both for the TCP listener that accepted the connection and the TCP endpoint into which it was accepted. The provided context is the one associated with the TCP listener.


Definition at line 646 of file include/openthread/tcp.h

otTcpListenerInitializeArgs#

typedef struct otTcpListenerInitializeArgs otTcpListenerInitializeArgs

This structure contains arguments to the otTcpListenerInitialize() function.


Definition at line 693 of file include/openthread/tcp.h

Function Documentation#

otTcpEndpointInitialize#

otError otTcpEndpointInitialize (otInstance *aInstance, otTcpEndpoint *aEndpoint, const otTcpEndpointInitializeArgs *aArgs)

Initializes a TCP endpoint.

Parameters
[in]aInstance

A pointer to an OpenThread instance.

[in]aEndpoint

A pointer to a TCP endpoint structure.

[in]aArgs

A pointer to a structure of arguments.

Calling this function causes OpenThread to keep track of the TCP endpoint and store and retrieve TCP data inside the aEndpoint. The application should refrain from directly accessing or modifying the fields in aEndpoint. If the application needs to reclaim the memory backing aEndpoint, it should call otTcpEndpointDeinitialize().


Definition at line 328 of file include/openthread/tcp.h

otTcpEndpointGetInstance#

otInstance * otTcpEndpointGetInstance (otTcpEndpoint *aEndpoint)

Obtains the otInstance that was associated with aEndpoint upon initialization.

Parameters
[in]aEndpoint

The TCP endpoint whose instance to obtain.

Returns

  • The otInstance pointer associated with aEndpoint.


Definition at line 341 of file include/openthread/tcp.h

otTcpEndpointGetContext#

void * otTcpEndpointGetContext (otTcpEndpoint *aEndpoint)

Obtains the context pointer that was associated with aEndpoint upon initialization.

Parameters
[in]aEndpoint

The TCP endpoint whose context to obtain.

Returns

  • The context pointer associated with aEndpoint.


Definition at line 352 of file include/openthread/tcp.h

otTcpGetLocalAddress#

const otSockAddr * otTcpGetLocalAddress (const otTcpEndpoint *aEndpoint)

Obtains a pointer to a TCP endpoint's local host and port.

Parameters
[in]aEndpoint

The TCP endpoint whose local host and port to obtain.

The contents of the host and port may be stale if this socket is not in a connected state and has not been bound after it was last disconnected.

Returns

  • The local host and port of aEndpoint.


Definition at line 365 of file include/openthread/tcp.h

otTcpGetPeerAddress#

const otSockAddr * otTcpGetPeerAddress (const otTcpEndpoint *aEndpoint)

Obtains a pointer to a TCP endpoint's peer's host and port.

Parameters
[in]aEndpoint

The TCP endpoint whose peer's host and port to obtain.

The contents of the host and port may be stale if this socket is not in a connected state.

Returns

  • The host and port of the connection peer of aEndpoint.


Definition at line 378 of file include/openthread/tcp.h

otTcpBind#

otError otTcpBind (otTcpEndpoint *aEndpoint, const otSockAddr *aSockName)

Binds the TCP endpoint to an IP address and port.

Parameters
[in]aEndpoint

A pointer to the TCP endpoint structure to bind.

[in]aSockName

The address and port to which to bind this TCP endpoint.


Definition at line 390 of file include/openthread/tcp.h

otTcpConnect#

otError otTcpConnect (otTcpEndpoint *aEndpoint, const otSockAddr *aSockName, uint32_t aFlags)

Records the remote host and port for this connection.

Parameters
[in]aEndpoint

A pointer to the TCP endpoint structure to connect.

[in]aSockName

The IP address and port of the host to which to connect.

[in]aFlags

Flags specifying options for this operation (see enumeration above).

Caller must wait for otTcpEstablished callback indicating that TCP connection establishment handshake is done before it can start sending data e.g., calling otTcpSendByReference().

The TCP Fast Open is not yet supported and aFlags is ignored.


Definition at line 418 of file include/openthread/tcp.h

otTcpSendByReference#

otError otTcpSendByReference (otTcpEndpoint *aEndpoint, otLinkedBuffer *aBuffer, uint32_t aFlags)

Adds data referenced by the linked buffer pointed to by aBuffer to the send buffer.

Parameters
[in]aEndpoint

A pointer to the TCP endpoint structure representing the TCP endpoint on which to send data.

[in]aBuffer

A pointer to the linked buffer chain referencing data to add to the send buffer.

[in]aFlags

Flags specifying options for this operation (see enumeration above).

Upon a successful call to this function, the linked buffer and data it references are owned by the TCP stack; they should not be modified by the application until a "send done" callback returns ownership of those objects to the application. It is acceptable to call this function to add another linked buffer to the send queue, even if the "send done" callback for a previous invocation of this function has not yet fired.

Note that aBuffer should not be chained; its mNext field should be NULL. If additional data will be added right after this call, then the OT_TCP_SEND_MORE_TO_COME flag should be used as a hint to the TCP implementation.


Definition at line 453 of file include/openthread/tcp.h

otTcpSendByExtension#

otError otTcpSendByExtension (otTcpEndpoint *aEndpoint, size_t aNumBytes, uint32_t aFlags)

Adds data to the send buffer by extending the length of the final otLinkedBuffer in the send buffer by the specified amount.

Parameters
[in]aEndpoint

A pointer to the TCP endpoint structure representing the TCP endpoint on which to send data.

[in]aNumBytes

The number of bytes by which to extend the length of the final linked buffer.

[in]aFlags

Flags specifying options for this operation (see enumeration above).

If the send buffer is empty, then the operation fails.


Definition at line 469 of file include/openthread/tcp.h

otTcpReceiveByReference#

otError otTcpReceiveByReference (otTcpEndpoint *aEndpoint, const otLinkedBuffer **aBuffer)

Provides the application with a linked buffer chain referencing data currently in the TCP receive buffer.

Parameters
[in]aEndpoint

A pointer to the TCP endpoint structure representing the TCP endpoint on which to receive data.

[out]aBuffer

A pointer to the linked buffer chain referencing data currently in the receive buffer.

The linked buffer chain is valid until the "receive ready" callback is next invoked, or until the next call to otTcpReceiveContiguify() or otTcpCommitReceive().


Definition at line 487 of file include/openthread/tcp.h

otTcpReceiveContiguify#

otError otTcpReceiveContiguify (otTcpEndpoint *aEndpoint)

Reorganizes the receive buffer to be entirely contiguous in memory.

Parameters