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
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.