RapidIO: The Next Generation Communication Fabric For Embedded Application

12.2. TYPE 9 PACKET FORMAT (DATA STREAMING CLASS)

The Type 9 packet format is the DATA STREAMING transaction format. Type 9 packets always have a data payload, unless they are terminating the PDU. Unlike other RapidIO logical specifications, the data payload length is defined as a multiple of half-words rather than double-words. A pad bit allows a sender to transmit an odd number of bytes in a packet. An odd bit indicates that the data payload has an odd number of half-words. This bit makes it possible for the destination to determine the end of a data payload if packet padding is done by the underlying transport. An extended header bit allows future expansion of the functionality of the Type 9 packet format. All of these bits are contained in the segmentation control field (SCF). The location and definition of these bits are described in Section 12.3.3. Definitions and encodings of fields specific to Type 9 packets are provided in Table 12.1. Table 12.2 details the various O and P bit combinations.

In addition to these basic fields, there are some specific 'constructs' that are important to data streaming. These constructs are composed of multiple fields. The first is the virtual stream ID or VSID. The VSID is a combination of the SourceID or DestinationID + Class + StreamID. The SourceID or DestID is used depending on the frame of reference. The egress, for example sees a stream as identified by the SourceID. VSIDs should be uniquely assigned for all streams in a system. Section ...