Appendix C
C-2 MIPS R4000 Microprocessor User's Manual
C.1 Sequential Ordering
Sequential ordering retrieves the data elements of a block in serial, or
sequential, order.
Figure C-1 shows a sequential order in which byte 0 is taken first and byte
7 is taken last.
Figure C-1 Retrieving a Data Block in Sequential Order
C.2 Subblock Ordering
Subblock ordering allows the system to define the order in which the data
elements are retrieved. The smallest data element of a block transfer for
the R400 is a doubleword, and Figure C-2 shows the retrieval of a block of
data that consists of 8 doublewords, in which DW2 is taken first.
Figure C-2 Retrieving Data in a Subblock Order
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7
Byte 0
taken first
Byte 1
taken second
Byte 2
taken third
Byte 3
taken fourth
Byte 4
taken fifth
Byte 5
taken sixth
Byte 6
taken seventh
Byte 7
taken last
DW0 DW1 DW2 DW3 DW4 DW5 DW6 DW7
DW0
taken third
DW1
taken fourth
DW2
taken first
DW 3
taken second
DW4
taken seventh
DW5
taken eighth
DW6
taken fifth
DW7
taken sixth
2 3 0 1 6 7 4 5
Order of retrieval
quadword
octalword
hexword (block)
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