A.5.228 PI2FW: Packed Word Integer to Single-Precision FP Convert
PI2FW mm1,mm2/m64 ; 0F 0F /r 0C [PENT,3DNOW]
PI2FW converts two signed 16-bit integers in the source operand to
single-precision FP values, and stores them in the destination operand.
The input values are in the low word of each doubleword.