This function is similar to netconn_new()
except that an additional function pointer callback is
passed. The function pointed to by callback will be called
when data is sent or received. Specifically, the netconn_evt
parameter to the callback is used to indicate the event type. This enum can have
the following values:
NETCONN_EVT_RCVPLUS
Used when new incoming data from a remote peer arrives. The amount of data
received is passed in len. If len
is 0 then a connection event has occurred: this may be an error, the
acceptance of a connection for a listening connection (called for the listening
connection), or deletion of the connection.
NETCONN_EVT_RCVMINUS
Used when new incoming data from a remote peer has been received and accepted
by higher layers. The amount of data accepted is passed in
len. If len
is 0 then this indicates the acceptance of a connection as a result of a
listening port (called for the newly created accepted connection).
NETCONN_EVT_SENDPLUS
Used when data has been sent to a remote peer and received by it. This only
occurs for TCP connections, and specifically is only triggered when, as a
consequence of TCP acknowledgements from the remote peer, the free TCP send
buffer size now exceeds the configured send buffer low water mark
(configured with the CYGNUM_LWIP_TCP_SNDLOWAT CDL
configuration option). The amount of data sent in the most recent
transaction is passed in len. If
len is 0 then this indicates the connection has been
deleted.
NETCONN_EVT_SENDMINUS
This is only used for TCP connections, and is triggered when
a sufficient amount of data has been sent on the connection that the
amount of free send buffer space is now under the send buffer low
water mark (configured with the CYGNUM_LWIP_TCP_SNDLOWAT
CDL configuration option). The amount of data sent in the most recent
transaction is passed in len.
