![](http://datasheet.mmic.net.cn/380000/-PD98405_datasheet_16745025/-PD98405_189.png)
CHAPTER 5 SAR FUNCTION
189
Figure 5-39. Example of Receive Data Configuration
Batch A VC#I
Batch B VC#J
Batch C VC#I
Packet n
Packet m
Receive indication
VC#I, packet m
Receive indication
VC#J, packet n
μ
PD98405 overwrites
and updates link pointer.
VC#I
Packet m
Buffer 1
VC#I
Packet m
Buffer 2
VC#I
Packet m
Buffer 3
VC#I
Packet m
Buffer 4
VC#J
Packet n
Buffer 1
Free buffer
Free buffer
Free buffer
VC#I
Packet m
Buffer 5
Free buffer
VC#I
Packet m
Buffer 6
Free buffer
Buffer address 1
Link pointer to C
Buffer address 2
Buffer address 3
Buffer address 4
Size
Size
Size
Size
Buffer address 1
Link pointer to C
Buffer address 2
Buffer address 3
Buffer address 4
Size
Size
Size
Size
Buffer address 1
Link pointer to D
Buffer address 2
Buffer address 3
Buffer address 4
Size
Size
Size
Size
The first cell of packet m of VC#I is received. The
μ
PD98405 reads the pool descriptor to fetch a batch.
At this time, batch A is allocated to packet m of VC#I because the first address of batch A is stored to
the pool descriptor.
Because batch A has been exhausted, the
μ
PD98405 updates the pool descriptor so that it indicates the
beginning of batch B.
While packet m is being received, the first cell of packet n of VC#J is received. The
μ
PD98405 allocates
batch B to packet n in the same manner as above.
VC#I fills the four free buffers of batch A before the packet has been entirely received, and newly
allocates batch C. At this time, the
μ
PD98405 overwrites, by means of DMA write, the link pointer of
batch A that points to batch B so that it indicates the beginning of batch C, and updates the link
information to "from batch A to batch C."