NASM 2.05 based x86 Instruction Reference[ch074]
A.5.54 CVTTPS2PI: Packed Single-Precision FP to Packed Signed INT32 Conversion with Truncation CVTTPS2PI mm,xmm/mem64 ; 0F 2C /r [KATMAI,SSE] CVTTPS2PI converts two packed single-precision FP values in the source operand to two packed signed doublewords in the destination operand. If the result is inexact, it is truncated (rounded toward zero). If the source is a register, the input values are in the low quadword. The destination operand is an MMX register. The source can be either an XMM register or a 64-bit memory location. If the source is a register, the input value is in the low quadword. For more details of this instruction, see the Intel Processor manuals.