
8201, 8202, 8203, 8204 Acceleration Processor Data Sheet, DS-0157-05
Page 91
Exar Confidential
Both the host and the 820x may read from and write to the Free Pool Ring; the host writes
to the ring at initialization, and the 820x reads from the ring when needed. After the 820x
has used a free pool entry, it will clear the Valid bit for that entry to inform the host that
the entry was used by a Channel Manager. After the host has finished processing a
Free_Pool_Len[13;0]
CMD_Index[13:0]
CPR
Reserved
END
VALID
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
Free_Pool_Adr[31:0]
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9876543210
Field Name
Bits
Default Description
Free_Pool_Len[13:0]
63:50
0
Free Pool Length.
This field indicates the size of the block defined by
the free pool descriptor. The size of the free pool
descriptor buffer is 8-bytes.
CMD_Index[13:0]
49:36
0
Command Index.
The index number of the command that used the
Free Pool entry.
CPR
35
0
Command Pointer Ring.
This bit identifies which command pointer ring used
the free pool entry.
0
Free pool entry is from a command in Command
Pointer Ring 0
1
Free pool entry is from a command in Command
Pointer Ring 1
Reserved
34
0
Reserved
END
33
0
End.
The command that used this entry is finished.
VALID
32
0
Entry Valid.
This bit indicates that the free pool entry is valid.
The host software will set this bit when writing a
new free pool entry. The 820x will clear this bit after
reading the free pool entry.
0
Free pool entry not valid
1
Free pool entry valid
Free_Pool_Adr[31:0]
31:0
0
Free Pool Buffer Starting Address.
The starting physical address of the descriptor free
pool. The Free Pool Entry format is the same for
both 32-bit and 64-bit addressing. Even if operating
in a 64-bit physical addressing environment, the
820x free pool physical addresses must be located
in the first 4GB (0 - 0xffffffff).
This field must be aligned on an 8 byte boundary.