CVTSD2SS—Convert Scalar Double-Precision FP Value to Scalar Single-Precision FP Value

Opcode/Instruction Op/En 64/32-bit Mode CPUID Feature Flag Description
F2 0F 5A /r CVTSD2SS xmm1, xmm2/m64 RM V/V SSE2 Convert one double-precision floating-point value in xmm2/m64 to one single-precision floating-point value in xmm1.
VEX.NDS.LIG.F2.0F.WIG 5A /r VCVTSD2SS xmm1,xmm2, xmm3/m64 RVM V/V AVX Convert one double-precision floating-point value in xmm3/m64 to one single-precision floating-point value and merge with high bits in xmm2.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (w) ModRM:r/m (r) NA NA
RVM ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA


Converts a double-precision floating-point value in the source operand (second operand) to a single-precision floating-point value in the destination operand (first operand).

The source operand can be an XMM register or a 64-bit memory location. The destination operand is an XMM register. When the source operand is an XMM register, the double-precision floating-point value is contained in the low quadword of the register. The result is stored in the low doubleword of the destination operand, and the upper 3 doublewords are left unchanged. When the conversion is inexact, the value returned is rounded according to the rounding control bits in the MXCSR register.

In 64-bit mode, use of the REX.R prefix permits this instruction to access additional registers (XMM8-XMM15). 128-bit Legacy SSE version: The destination and first source operand are the same. Bits (VLMAX-1:32) of the corresponding YMM destination register remain unchanged. VEX.128 encoded version: Bits (127:64) of the XMM register destination are copied from corresponding bits in the first source operand. Bits (VLMAX-1:128) of the destination YMM register are zeroed.


CVTSD2SS (128-bit Legacy SSE version)
DEST[31:0] ← Convert_Double_Precision_To_Single_Precision_Floating_Point(SRC[63:0]);
(* DEST[VLMAX-1:32] Unmodified *)
VCVTSD2SS (VEX.128 encoded version)
DEST[31:0] ← Convert_Double_Precision_To_Single_Precision_Floating_Point(SRC2[63:0]);
DEST[127:32] ← SRC1[127:32]
DEST[VLMAX-1:128] ← 0

Intel C/C++ Compiler Intrinsic Equivalent

CVTSD2SS: __m128 _mm_cvtsd_ss(__m128 a, __m128d b)

SIMD Floating-Point Exceptions

Overflow, Underflow, Invalid, Precision, Denormal.

Other Exceptions

See Exceptions Type 3.