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CVTTPS2PI—Convert with Truncation Packed Single-Precision FP Values to Packed Dword Integers

Opcode/Instruction Op/En 64-Bit Mode Compat/Leg Mode Description

0F 2C /r

CVTTPS2PI mm, xmm/m64

RM Valid Valid Convert two single-precision floating-point values from xmm/m64 to two signed doubleword signed integers in mm using truncation.

Instruction Operand Encoding

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


Converts two packed single-precision floating-point values in the source operand (second operand) to two packed signed doubleword integers 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 MMX technology register. When the source operand is an XMM register, the two single-precision floating-point values are 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, and if this exception is masked, the indefinite integer value (80000000H) is returned.

This instruction causes a transition from x87 FPU to MMX technology operation (that is, the x87 FPU top-of-stack pointer is set to 0 and the x87 FPU tag word is set to all 0s [valid]). If this instruction is executed while an x87 FPU floating-point exception is pending, the exception is handled before the CVTTPS2PI instruction is executed.

In 64-bit mode, use of the REX.R prefix permits this instruction to access additional registers (XMM8-XMM15).


DEST[31:0] ← Convert_Single_Precision_Floating_Point_To_Integer_Truncate(SRC[31:0]);
DEST[63:32] ← Convert_Single_Precision_Floating_Point_To_Integer_Truncate(SRC[63:32]);

Intel C/C++ Compiler Intrinsic Equivalent

__m64 _mm_cvttps_pi32(__m128 a)

SIMD Floating-Point Exceptions

Invalid, Precision

Other Exceptions

See Table 22-5, “Exception Conditions for Legacy SIMD/MMX Instructions with XMM and FP Exception,” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3B.