NASM 2.05 based x86 Instruction Reference[ch066]
A.5.46 CVTSD2SS: Scalar Double-Precision FP to Scalar Single-Precision FP Conversion CVTSD2SS xmm1,xmm2/mem64 ; F2 0F 5A /r [KATMAI,SSE] CVTSD2SS converts a double-precision FP value from the source operand to a single-precision FP value in the low doubleword of the destination operand. The upper 3 doublewords are left unchanged. The destination operand is an XMM register. The source can be either an XMM register or a 64-bit memory location. If the source is a register, the input value is in the low quadword. For more details of this instruction, see the Intel Processor manuals.