Chapter 16
416 MIPS R4000 Microprocessor User's Manual
As an example of this process, SECDED ECC for Data(63:0) = 0x0000 0000
0000 0001 is generated in the steps below.
1. Find any bits in Data(63:0) having a value of 1.
To determine this, the 16-bit hexadecimal value of 0x0000 0000
0000 0001 must be expanded to its 64-bit binary equivalent before
locating the data bit(s) with a value of 1. In this case, the only 1-
value in 0x0000 0000 0000 0001 is in column 0.
2. Find the check bits in column 0.
They are 0001 0011
2.
3. Take even parity of check bits 0001 0011
2
.
ECC Parity (even)
MSB (7) 0 0
(6) 0 0
(5) 0 0
(4) 1 1
(3) 0 0
(2) 0 0
(1) 1 1
LSB (0) 1 1
4. This even parity value, 0001 0011
2
, is sent out over the bus as ECC
check bits, ECC(7:0).
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