CVTTSD2SI—Convert with Truncation Scalar Double-Precision FP Value to Signed Integer

Opcode/Instruction	Op/En	64/32-bit Mode	CPUID Feature Flag	Description
F2 0F 2C /r CVTTSD2SI r32, xmm/m64	RM	V/V	SSE2	Convert one double-precision floating-point value from xmm/m64 to one signed doubleword integer in r32 using truncation.
F2 REX.W 0F 2C /r CVTTSD2SI r64, xmm/m64	RM	V/N.E.	SSE2	Convert one double precision floating-point value from xmm/m64 to one signedquadword integer in r64 using truncation.
VEX.LIG.F2.0F.W0 2C /r VCVTTSD2SI r32, xmm1/m64	RM	V/V	AVX	Convert one double-precision floating-point value from xmm1/m64 to one signed doubleword integer in r32 using truncation.
VEX.LIG.F2.0F.W1 2C /r VCVTTSD2SI r64, xmm1/m64	RM	V/N.E.¹	AVX	Convert one double precision floating-point value from xmm1/m64 to one signed quadword integer in r64 using truncation.

NOTES:

1. Encoding the VEX prefix with VEX.W=1 in non-64-bit mode is ignored.

Instruction Operand Encoding

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

Description

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

When a conversion is inexact, a truncated (round toward zero) result is returned. If a converted result is larger than the maximum signed doubleword integer, the floating point invalid exception is raised. If this exception is masked, the indefinite integer value (80000000H) is returned.

Legacy SSE instructions: In 64-bit mode, Use of the REX.W prefix promotes the instruction to 64-bit operation. See the summary chart at the beginning of this section for encoding data and limits.

Note: In VEX-encoded versions, VEX.vvvv is reserved and must be 1111b, otherwise instructions will #UD.

Operation

IF 64-Bit Mode and OperandSize = 64
    THEN
         DEST[63:0] ← Convert_Double_Precision_Floating_Point_To_
                           Integer64_Truncate(SRC[63:0]);
    ELSE
         DEST[31:0] ← Convert_Double_Precision_Floating_Point_To_
                          Integer32_Truncate(SRC[63:0]);
FI;

Intel C/C++ Compiler Intrinsic Equivalent

int _mm_cvttsd_si32(__m128d a)

__int64 _mm_cvttsd_si64(__m128d a)

SIMD Floating-Point Exceptions

Invalid, Precision.

Other Exceptions

See Exceptions Type 3; additionally

#UD	If VEX.vvvv ≠ 1111B.