Intel NETWORK PROCESSOR IXP2800 - Manual (Page 44)

44 Hardware Reference Manual
Intel
®
IXP2800 Network Processor
Technical Description
Example 10 shows a big-endian align sequence of instructions and the value of the various
operands. Table 7 shows the data in the registers for this example. The value in
BYTE_INDEX[1:0] CSR (which controls the shift amount) for this example is 2.
Figure 6. Byte-Align Block Diagram
A9353-01
Prev_A
Byte_Index
Result
B_Operand A_Operand
Prev_B
. . . . . .
Shift
Table 7. Register Contents for Example 10
Register
Byte 3
[31:24]
Byte 2
[23:16]
Byte 1
[15:8]
Byte 0
[7:0]
0 0 1 2 3
1 4 5 6 7
2 8 9 A B
3 C D E F
Example 10. Big-Endian Align
Instruction Prev B A Operand B Operand Result
Byte_align_be[--, r0] -- -- 0123 --
Byte_align_be[dest1, r1]
0123 0123 4567 2345
Byte_align_be[dest2, r2] 4567 4567 89AB 6789
Byte_align_be[dest3, r3]
89AB 89AB CDEF ABCD
NOTE: A Operand comes from Prev_B register during byte_align_be instructions.