NASM 2.05 based x86 Instruction Reference[ch073]
A.5.53 CVTTPS2DQ: Packed Single-Precision FP to Packed Signed INT32 Conversion with Truncation CVTTPS2DQ xmm1,xmm2/mem128 ; F3 0F 5B /r [WILLAMETTE,SSE2] CVTTPS2DQ converts four packed single-precision FP values in the source operand to four packed signed doublewords in the destination operand. If the result is inexact, it is truncated (rounded toward zero). The destination operand is an XMM register. The source can be either an XMM register or a 128-bit memory location. For more details of this instruction, see the Intel Processor manuals.