![](http://datasheet.mmic.net.cn/390000/TSB42AA4I_datasheet_16839080/TSB42AA4I_73.png)
58
5.2.2
Block Receive
The block-receive format through the data buffer is shown in Figure 56 and is described in Table 59.The
first quadlet contains the packet control token which is added by ceLynx. The first 16 bits of the second
quadlet contain the node and bus ID of the source node, and the last 16 bits of the second quadlet and all
of the third quadlet contain the 48-bit, quadlet-aligned destination offset address. All remaining quadlets,
except for the last one, contain data that is used only for write requests and read responses. For block read
requests and block write responses, the data field is omitted.
rsv
30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
31
destination Offset Low
destination Offset High
destination ID
priority
t Code
rt
t Label
rsv
pad
ackCode
P
S
spd
r
Data Size
source ID
data length
extended_tCode
block data (if any)
Figure 57. Block Receive Format
Table 59. Block Receive Format Functions
FIELD NAME
DESCRIPTION
S
Packet control token - This bit is set to 1 whenever the packet control token is attached to
a self-ID packet.
Data Size
Packet control token - Size of the packet in quadlets
P
Packet control token - This bit is set to 1 whenever the packet control token is attached to a
PHY packet.
ackCode
Packet control token - This 5-bit field holds the acknowledge code sent by the receiver for the
current packet. See Table 510 for ACK codes.
pad
Packet control token - Number of padding bytes added
spd
Packet control token - The spd field indicates the speed at which the current packet was sent.
00 = 100 Mbits/s, 01 =200 Mbits/s, 10 = 400 Mbits/s, and 11 is undefined for this
implementation.
destination ID
The destinationID field is the concatenation of the 10–bit bus number and the 6-bit node
number that forms the node address to which the current packet is being sent.
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 contains 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 610 of the
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).
source ID
The sourceID field contains the node ID of the sender of the current packet.