NASM 2.05 based x86 Instruction Reference[ch283]
A.5.259 PSUBSxx, PSUBUSx: Subtract Packed Integers With Saturation PSUBSB mm1,mm2/m64 ; 0F E8 /r [PENT,MMX] PSUBSW mm1,mm2/m64 ; 0F E9 /r [PENT,MMX] PSUBSB xmm1,xmm2/m128 ; 66 0F E8 /r [WILLAMETTE,SSE2] PSUBSW xmm1,xmm2/m128 ; 66 0F E9 /r [WILLAMETTE,SSE2] PSUBUSB mm1,mm2/m64 ; 0F D8 /r [PENT,MMX] PSUBUSW mm1,mm2/m64 ; 0F D9 /r [PENT,MMX] PSUBUSB xmm1,xmm2/m128 ; 66 0F D8 /r [WILLAMETTE,SSE2] PSUBUSW xmm1,xmm2/m128 ; 66 0F D9 /r [WILLAMETTE,SSE2] PSUBSx and PSUBUSx subtracts packed integers in the source operand from those in the destination operand, and use saturation for results that are outside the range supported by the destination operand. - PSUBSB operates on signed bytes, and uses signed saturation on the results. - PSUBSW operates on signed words, and uses signed saturation on the results. - PSUBUSB operates on unsigned bytes, and uses signed saturation on the results. - PSUBUSW operates on unsigned words, and uses signed saturation on the results.