A.5.225 PFSUB: Packed Single-Precision FP Subtract
PFSUB mm1,mm2/m64 ; 0F 0F /r 9A [PENT,3DNOW]
PFSUB subtracts the single-precision FP values in the source from those
in the destination, and stores the result in the destination operand.
dst[0-31] := dst[0-31] - src[0-31],
dst[32-63] := dst[32-63] - src[32-63].