Graphical Representation Of _Packxx2 Intrinsics - Texas Instruments TMS320C6000 Programmer's Manual

Figure 8–3. Graphical Representation of _packXX2 Intrinsics
b
b_hi b_lo
b
b_hi b_lo
b_hi
c
b
b_hi b_lo
b_hi
b
b_hi b_lo
b_lo
The saturating pack intrinsic, _spack2, is closely related to the _pack2 intrin-
sic. The main difference is that the saturating pack first saturates the signed
32-bit source values to signed 16-bit quantities, and then packs these results
into a single 32-bit word. This makes it easier to support applications which
generate some intermediate 32-bit results, but need a signed 16-bit result at
the end. Figure 8–4 shows _spack2's operation graphically.
Packed-Data Processing on the 'C64x
a
a_hi a_lo
b_lo a_lo
c
a
a_hi a_lo
a_hi
a
a_hi a_lo
a_lo
c
a
a_hi a_lo
a_hi
c
'C64x Programming Considerations
c = _pack2(b, a)
c=_packh2(b, a)
c=_packhl2(b, a)
c=_packlh2(b, a)
8-9