Datasheet

4–9

4.2.2 Block Receive

The IEEE 1394-1995 standard specified four types of block receive packets: write request, read request,

write response, and read response packet. Refer to Table 4–4 for a description of the packet fields.

4.2.2.1 Block Write-Request and Read-Request Packets

The format for a block write-request packet is shown in Figure 4–13. The first quadlet read from the GRF

is the packet token described in section 3.3.4. It contains packet-reception status information added by the

TSB12LV01B. The first 16 bits of the second quadlet contains the destination node and bus ID, and the

remaining 16 bits contain the packet control information. The first 16 bits of the third quadlet contain the node

and bus ID of the source, and the remaining 16 bits of the third quadlet and the entire fourth quadlet contain

the 48-bit, quadlet aligned destination offset address. The first 16 bits of the fifth quadlet contains the

dataLength field. The remaining 16 bits represent the extended_tCode field. The block data, if any, follows

the extended_tCode. The format for a block read-request packet is shown in Figure 4–14.

tLabel rt tCode priority

sourceID destinationOffsetHigh

destinationOffsetLow

block data (if any)

destinationID

dataLength extended_tCode

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

PacCom

spd WriteCount tCode ackSent

Reserved

Figure 4–13. Block-Receive Format (Write Request)