Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
491
Application DMA Unit—Intel
®
81341 and 81342
5.7.2
XOR Operation
describes the XOR algorithm implementation. In this illustrative example,
there are four blocks of source data to be XOR-ed. The intermediate result is kept by
the XOR store queue in the ADMA before being written back to local memory. The
source data is located at addresses 0 A000 0400H, 0 A000 0800H, 0 A000 0C00H and 0
A000 1000H respectively.
All data transfers needed for this operation are controlled by chain descriptors located
in local memory. The Application DMA as a master on the internal bus initiates a data
transfer. The algorithm is implemented such that as data is read from local memory,
the boolean unit executes the XOR operation on incoming data.
Figure 57. The Bit-wise XOR Algorithm
0A0000400H
Block 1
MSB
LSB
0A0000800H
0A0000C00H
0A0001000H
bitwise-XOR
(64-bit wide)
bitwise-XOR
(64-bit wide)
bitwise-XOR
(64-bit wide)
1K byte
byte
1
byte 8
1024 bytes
bytes 1-8
1024 bytes
bytes 1-8
1024 bytes
bytes 1-8
bytes 1-8
1024 bytes
Block 2
Block 3
Block 4
..
.
..
.
..
.
SAR2 = 0 A000 0C00H
ADAR = B000 0400H
SAR3 = 0 A000 1000H
SAR1 = 0 A000 0800H
SAR0 = 0 A000 0400H
ABCR = 0000 0400H
ADCR = 0000 001FH
Control Register Values
0B0000400H
128-Deep
Store Queue
Local Memory
B6226-01
Note: All of the Source Data Streams are required to be in Local Memory for the XOR
operation to operate properly. The ADMA does not support Source Data streams for XOR
operations that are located in Host Memory or the Internal Bus. However, the ADMA
does provide for the Parity stripe to be written to the Host Memory or the Internal Bus