NASM 2.05 based x86 Instruction Reference[ch199]

A.5.177 MOVQ2DQ: Move Quadword from MMX to XMM register. MOVQ2DQ xmm,mm ; F3 OF D6 /r [WILLAMETTE,SSE2] MOVQ2DQ moves the quadword from the source operand to the low quadword of the destination operand, and clears the high quadword.