NASM 2.05 based x86 Instruction Reference[ch191]

A.5.169 MOVMSKPD: Extract Packed Double-Precision FP Sign Mask MOVMSKPD reg32,xmm ; 66 0F 50 /r [WILLAMETTE,SSE2] MOVMSKPD inserts a 2-bit mask in r32, formed of the most significant bits of each double-precision FP number of the source operand.