VCVTSS2USI—Convert Scalar Single Precision Floating-Point Value to Unsigned Doubleword Integer

Opcode/Instruction	Op /En	64/32 bit Mode Support	CPUID Feature Flag	Description
EVEX.LLIG.F3.0F.W0 79 /r VCVTSS2USI r32, xmm1/m32{er}	A	V/V	AVX512F	Convert one single precision floating-point value from xmm1/m32 to one unsigned doubleword integer in r32.
EVEX.LLIG.F3.0F.W1 79 /r VCVTSS2USI r64, xmm1/m32{er}	A	V/N.E.¹	AVX512F	Convert one single precision floating-point value from xmm1/m32 to one unsigned quadword integer in r64.

NOTES:

1. EVEX.W1 in non-64 bit is ignored; the instruction behaves as if the W0 version is used.

Instruction Operand Encoding

Op/En	Tuple Type	Operand 1	Operand 2	Operand 3	Operand 4
A	Tuple1 Fixed	ModRM:reg (w)	ModRM:r/m (r)	N/A	N/A

Description

Converts a single precision floating-point value in the source operand (the second operand) to an unsigned double-word integer (or unsigned quadword integer if operand size is 64 bits) in the destination operand (the first operand). The source operand can be an XMM register or a memory location. The destination operand is a general-purpose register. When the source operand is an XMM register, the single precision floating-point value is contained in the low doubleword of the register.

When a conversion is inexact, the value returned is rounded according to the rounding control bits in the MXCSR register or the embedded rounding control bits. If a converted result cannot be represented in the destination format, the floating-point invalid exception is raised, and if this exception is masked, the integer value 2^w – 1 is returned, where w represents the number of bits in the destination format.

VEX.W1 and EVEX.W1 versions: promotes the instruction to produce 64-bit data in 64-bit mode.

Note: EVEX.vvvv is reserved and must be 1111b, otherwise instructions will #UD.

Operation

VCVTSS2USI (EVEX Encoded Version)

IF (SRC *is register*) AND (EVEX.b = 1)

THEN

SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(EVEX.RC);

ELSE

SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(MXCSR.RC);

FI;

IF 64-bit Mode and OperandSize = 64

THEN

DEST[63:0] := Convert_Single_Precision_Floating_Point_To_UInteger(SRC[31:0]);

ELSE

DEST[31:0] := Convert_Single_Precision_Floating_Point_To_UInteger(SRC[31:0]);

FI;

Intel C/C++ Compiler Intrinsic Equivalent

VCVTSS2USI unsigned _mm_cvtss_u32( __m128 a);

VCVTSS2USI unsigned _mm_cvt_roundss_u32( __m128 a, int r);

VCVTSS2USI unsigned __int64 _mm_cvtss_u64( __m128 a);

VCVTSS2USI unsigned __int64 _mm_cvt_roundss_u64( __m128 a, int r);

SIMD Floating-Point Exceptions

Invalid, Precision.

Other Exceptions

EVEX-encoded instructions, see Table 2-48, “Type E3NF Class Exception Conditions.”