Intel NETWORK PROCESSOR IXP2800 - Manual (Page 175)

Hardware Reference Manual 175
Intel
®
IXP2800 Network Processor
Microengines
Example 24 shows an align sequence of instructions and the value of the various operands.
Table 59 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 58. Byte Align Block Diagram
A9353-01
Prev_A
Byte_Index
Result
B_Operand A_Operand
Prev_B
. . . . . .
Shift
Table 59. Register Contents for Example 23
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 24. 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.