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Source code

CVTTPS2PI

Convert With Truncation Packed Single Precision Floating-Point Values to Packed

stableVMJITAOTinstruction

Encodings

OpcodeInstructionOp/En64-bitCompat/LegacyDescription
NP 0F 2C /rCVTTPS2PI mm, xmm/m64RMValidValidConvert two single precision floating-point values from xmm/m64 to two signed doubleword signed integers in mm using truncation.

Operand encoding

Each mode is a value of the Op/En column above. It says which field of the encoded instruction carries each operand, in the order they are written, and whether the instruction reads it, writes it or both.

RM

  1. modrm.reg escrituraModRM byte, reg field (bits 5-3)
  2. modrm.rm lecturaModRM byte, r/m field (bits 2-0); with the SIB byte and the displacement when the mod field asks for them

Measured cost

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Description

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).

Operation

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 intrinsics

CVTTPS2PI __m64 _mm_cvttps_pi32(__m128 a);

SIMD Floating-Point Exceptions

Invalid, Precision.

Other Exceptions

See Section 25.25.3, "Exception Conditions of Legacy SIMD Instructions Operating on MMX Registers" in the Intel(R) 64 and IA-32 Architectures Software Developer's Manual, Volume 3B.

Sources