Texas Instruments TMS320C6000 Programmer's Manual page 312

Packed-Data Processing on the 'C64x
Figure 8–6. Graphical Representation of 8–bit Unpacks (_unpkXu4)
00000000
00000000
8-12
a_3
a_3 00000000
b
a
a_3 a_2 a_1
a_1
b
The 'C64x also provides a handful of additional byte-manipulating operations
that have proven useful in various algorithms. These operations are neither
packs nor unpacks, but rather shuffle bytes within a word. Uses include con-
volution-oriented algorithms, complex number arithmetic, and so on. Opera-
tions in this category include the intrinsics _shlmb, _shrmb, _swap4, and _rotl.
The first three in this list are illustrated in Figure 8–7.
a
a_2 a_1
a_2
a_0
00000000 a_0
a_0
b = unpkhu4(a);
b = unpklu4(a);