Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
693
SRAM Memory Controller—Intel
®
81341 and 81342
8.3.4.1
Parity Generation
The direct memory port interface of the SMCU only generates data parity before
delivering data onto the port. After the requested data is read from memory and ECC
has been verified, the direct memory port interface generates even data parity before
delivering the data on the direct memory port.
lists the data bytes that are
used for data parity calculation. The parity bits are calculated by bit XORing the data
bits as shown in
. As an example, the parity calculation for the lowest order
byte of the data bus D[7:0] is calculated as follows:
Note:
The direct memory port does not support address parity.
Equation 32.D_PARITY0 = D[0] XOR D[1] XOR D[2] XOR D[3] XOR D[4] XOR D[5] XOR
D[6] XOR D[7] XOR BE[0]
Table 417. Data Parity Checking/Generation
Data Parity Bit
Data Byte
Byte Enable
D_PARITY15
D[127:120]
BE[15]
D_PARITY14
D[119:112]
BE[14]
D_PARITY13
D[111:104]
BE[13]
D_PARITY12
D[103:96]
BE[12]
D_PARITY11
D[95:88]
BE[11]
D_PARITY10
D[87:80]
BE[10]
D_PARITY9
D[79:72]
BE[9]
D_PARITY8
D[71:64]
BE[8]
D_PARITY7
D[63:56]
BE[7]
D_PARITY6
D[55:48]
BE[6]
D_PARITY5
D[47:40]
BE[5]
D_PARITY4
D[39:32]
BE[4]
D_PARITY3
D[31:24]
BE[3]
D_PARITY2
D[23:16]
BE[2]
D_PARITY1
D[15:8]
BE[1]
D_PARITY0
D[7:0]
BE[0]