LLC_CCB Overview  Group

The LLC_CCB structure represents a command control block. You pass a pointer to this structure to the AcsLan function.

typedef struct _LLC_CCB {

    UCHAR uchAdapterNumber; 

    UCHAR uchDlcCommand; 

    UCHAR uchDlcStatus; 

    UCHAR uchReserved1; 

    struct _LLC_CCB *pNext;

    ULONG ulCompletionFlag;

    CCB_PARMS u;

    HANDLE hCompletionEvent;

    UCHAR uchReserved2; 

    UCHAR uchReadFlag; 

    USHORT usReserved3

} LLC_CCB, *PLLC_CCB;

Members

uchAdapterNumber

Specifies adapter number 0 or 1.

uchDlcCommand

Specifies the command code. The following command codes are supported.

Code	Meaning
LLC_BUFFER_CREATE	Creates a new DLC buffer pool and returns its handle. The application must open at least one adapter before it can create the buffer pool.
LLC_BUFFER_FREE	Returns one or more buffers to the adapter pool. The buffers must have been obtained with the LLC_BUFFER_GET command.
LLC_BUFFER_GET	Returns the requested buffers. You can retrieve several buffers of the same size or an optimal set of buffers for the specified frame size.
LLC_DIR_CLOSE_ADAPTER	Closes the adapter logically, releasing its resources and canceling any pending commands. Open SAPs or link stations are reset before the completion of this command. Canceled commands return the error code LLC_STATUS_CANCELLED_BY_SYSTEM_ACTION. Functional address bits are reset. The pNext member receives the address of a queue of CCBs terminated by this command.
LLC_DIR_CLOSE_DIRECT	Releases ownership of all direct stations. If you use an LLC_READ command to post this command, the system returns the buffers from the direct buffer pool in the parameter table.
LLC_DIR_INITIALIZE	Resets the network adapter, returns any pending commands, and releases buffer resources. For security reasons, the command resets the adapter physically only if it was not functioning normally when you issued the command.
LLC_DIR_INTERRUPT	This command does not do anything under Windows. No parameter table is required.
LLC_DIR_OPEN_ADAPTER	Prepares the protocol drivers for network communication. The adapter must be in a logically closed state for this command to succeed.
LLC_DIR_OPEN_DIRECT	Gives the application ownership of the direct station and enables it to receive frames using the LLC_RECEIVE command.
LLC_DIR_READ_LOG	Reads and resets the adapter logs. The system transfers the log data to the buffer in the parameter table.
LLC_DIR_SET_EXCEPTION_FLAGS	Defines user-notification flags so the system notifies the application of exception conditions.
LLC_DIR_SET_FUNCTIONAL_ADDRESS	Sets or resets the functional addresses for the adapter to receive messages.
LLC_DIR_SET_GROUP_ADDRESS	Sets or resets the group address for which the adapter will receive messages. Only one application can set a group address for a Token-Ring adapter. This command can fail if the Ethernet adapter does not have an available multicast address.
LLC_DIR_SET_MULTICAST_ADDRESS	Sets a 48-bit multicast address for the current DLC adapter context. The application must issue this command before it can receive multicasts. This command is supported only on Ethernet networks and is an alternative to the LLC_DIR_SET_GROUP_ADDRESS command. This command can fail if the Ethernet adapter does not have an available multicast address. A value of zero removes the previous multicast address.
LLC_DIR_STATUS	Reads the general status information. You can issue this command before the LLC_DIR_OPEN_ADAPTER command, but after the LLC_DIR_INITIALIZE command.
LLC_DIR_TIMER_CANCEL	Cancels a timer that was previously initiated by an LLC_DIR_TIMER_SET command.
LLC_DIR_TIMER_CANCEL_GROUP	Cancels a group of timer commands that were previously initiated by the LLC_DIR_TIMER_SET command.
LLC_DIR_TIMER_SET	Initiates a programmable timer to expire after a designated interval.
LLC_DLC_CLOSE_SAP	Closes a SAP. The SAP cannot close unless all link stations are closed.
LLC_DLC_CLOSE_STATION	Closes a link station.
LLC_DLC_CONNECT_STATION	Starts or completes a connection between the local and remote link stations. Both the local station and the remote station must issue the command to establish the connection.
LLC_DLC_FLOW_CONTROL	Controls the flow of data across a single link station on a SAP or across every link station on a SAP. You should issue this command immediately after a link station enters a local busy state. The driver clears the busy state when there are enough free buffers to receive more frames.
LLC_DLC_MODIFY	Modifies the work values of an open link station or the default values of a SAP.
LLC_DLC_OPEN_SAP	Activates a SAP and reserves a number of link stations for the SAP.
LLC_DLC_OPEN_STATION	Allocates resources for a link station.
LLC_DLC_REALLOCATE_STATIONS	Reallocates the number of link stations allocated to a SAP. When reducing the number of stations, the command returns the deallocated stations to the adapter pool. When increasing the number of stations, the command assigns new stations from the adapter pool.
LLC_DLC_RESET	Resets the SAPs and their associated link stations. Affected resources are freed, and pending commands are terminated.
LLC_DLC_SET_THRESHOLD	Sets a threshold for the SAP or direct station’s buffer pool. The application is notified whenever the number of buffers in the pool falls below this threshold.
LLC_DLC_STATISTICS	Reads and optionally resets the DLC log. The log is transferred to the buffer indicated by the parameter table.
LLC_READ	Performs a read operation. The operation is complete when the system sets the uchDlcStatus member and the sets the hCompletionEvent event to the signaled state. The data and optional header begin at offset 64.
LLC_READ_CANCEL	Cancels a pending LLC_READ command for the application.
LLC_RECEIVE	Receives data. The command fails if the application has not created a buffer pool.
LLC_RECEIVE_CANCEL	Cancels a pending LLC_RECEIVE command.
LLC_RECEIVE_MODIFY	Receives data and puts some of it into a user buffer.
LLC_TRANSMIT_DIR_FRAME	Transmits data to the direct station.
LLC_TRANSMIT_I_FRAME	Transmits information data to a link station.
LLC_TRANSMIT_TEST_CMD	Requests the adapter to transmit a test command frame with the poll bit set. You can only use this command with a SAP.
LLC_TRANSMIT_UI_FRAME	Transmits unnumbered information data for a SAP. You can use this command only with a SAP.
LLC_TRANSMIT_XID_CMD	Transmits an XID command with the poll bit set on. You can use this command only with a SAP.
LLC_TRANSMIT_XID_RESP_FINAL	Transmits an XID response with the final bit on. You can only use this command with a SAP opened with SAP options specifying that the application will handle XID commands.
LLC_TRANSMIT_XID_RESP_NOT_FINAL	Transmits an XID response with the final bit off. You can only use this command with a SAP opened with SAP options specifying that the application will handle XID commands.

uchDlcStatus

Receives the command completion code. This value is set to LLC_STATUS_PENDING when the command is received. It is set to an appropriate code when the command is completed. For a list of the command completion codes, see the following Remarks section.

uchReserved1

Reserved.

pNext

Specifies the next command control block in the chain. Otherwise, set this parameter to NULL.

ulCompletionFlag

An optional flag set when an LLC_READ command is completed. If you set this parameter to zero before the command is issued, it is not used.

u

Specifies the address of a CCB_PARMS structure representing the parameter table.

hCompletionEvent

Specifies a handle to an event that you can use to check for command completion. Otherwise, set this parameter to zero. When the command is completed, it sets the event to the signaled state.

uchReserved2

Windows NT: Not used.

Windows 95: The identifier of the application issuing the command. This value is returned by the LLC_DIR_OPEN_ADAPTER command and is used for all subsequent commands.

uchReadFlag

Specifies that an LLC_READ command control block is chained in this command. Otherwise, set this parameter to zero.

usReserved3

Reserved.

Remarks

The uchDlcStatus member receives an LLC_STATUS value representing the command completion code. LLC_STATUS is an enumerated type. The following completion codes are defined:

See Also

AcsLan, CCB_PARMS

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