Intel 253666-024US - Manual (Page 283)

Vol. 2A 3-237
INSTRUCTION SET REFERENCE, A-M
CVTTPD2PI—Convert with Truncation Packed Double-Precision Floating-Point Values to
Packed Doubleword Integers
CVTTPD2PI—Convert with Truncation Packed Double-Precision
Floating-Point Values to Packed Doubleword Integers
Description
Converts two packed double-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 128-bit
memory location. The destination operand is an MMX technology 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 CVTTPD2PI 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_Double_Precision_Floating_Point_To_Integer_Truncate(SRC[63:0]);
DEST[63:32] ← Convert_Double_Precision_Floating_Point_To_Integer_
Truncate(SRC[127:64]);
Intel C/C++ Compiler Intrinsic Equivalent
CVTTPD1PI__m64 _mm_cvttpd_pi32(__m128d a)
SIMD Floating-Point Exceptions
Invalid, Precision.
Protected Mode Exceptions
#GP(0) For an illegal memory operand effective address in the CS, DS,
ES, FS or GS segments.
Opcode Instruction 64-Bit
Mode
Compat/
Leg Mode
Description
66 0F 2C /r CVTTPD2PI mm,
xmm/m128
Valid Valid Convert two packer double-precision
floating-point values from xmm/m128
to two packed signed doubleword
integers in mm using truncation.