7
–
2
Table 7
–
1. Quadlet-Transmit Format Functions
FIELD NAME
DESCRIPTION
spd
The spd field indicates the speed at which the current packet is to be sent. 00 = 100 Mb/s,
01 = 200 Mb/s, and 10 = 400 Mb/s, and 11 is undefined for this implementation.
tLabel
The tLabel field is the transaction label, which is a unique tag for each outstanding transaction
between two nodes. This field is used to pair up a response packet with its corresponding
request packet.
rt
The rt field is the retry code for the current packet is: 00 = new, 01 = retry_X, 10 = retryA, and
11 = retryB.
tCode
The tCode field is the transaction code for the current packet (see Table 6
–
10 of IEEE
–
1394
standard).
priority
The priority field contains the priority level for the current packet. For cable implementation,
the value of the bits must be zero (for backplane implementation, see clause 5.4.1.3 and
5.4.2.1 of the IEEE
–
1394 standard).
destinationID
The destinationID field is the concatenation of the 10-bit bus number and the 6-bit node
number that forms the destination node address of the current packet.
destination OffsetHigh,
destination OffsetLow
The concatenation of these two fields addresses a quadlet in the destination node address
space. This address must be quadlet aligned (modulo 4).
quadlet data
For write requests and read responses, the quadlet data field holds the data to be transferred.
For write responses and read requests, this field is not used and should not be written into the
FIFO.
rcode
Specifies the result of the read request transaction. The response codes that may be
returned to the requesting agent are defined as follows:
Response
Code
Name
Description
0
1
–
3
4
5
6
7
8-Fh
resp_complete
reserved
resp_conflict_error
resp_data_error
resp_type_error
resp_address_error
reserved
Node successfully completed requested operation
Resource conflict detected by responding agent.
Request may be retried.
Hardware error. Data not available.
Field within request packet header contains un
supported or invalid vallue.
Address location within specified node not accessible
7.1.2
The block-transmit format is shown in Figure 7
–
3 and is described in Table 7
–
2. The first quadlet contains
packet-control information. The second and third quadlets contain the 64-bit address. The first 16 bits of the
fourth quadlet contains the dataLength field. This is the number of bytes of data in the packet. The remaining
16 bits represent the extended_tCode field (see Table 6
–
11 of the IEEE
–
1394 standard for more information
on extended_tCodes). The block data, if any, follows the extended_tCode.
Block Transmit