NASM 2.05 based x86 Instruction Reference[ch163]

A.5.141.1 Pseudo-code examples a16 LODSB without segment override and with Direction Flag clear (UP) is equal to MOV AL, BYTE [SI] LEA SI, [SI + 1] a32 ES LODSD with Direction Flag set (DN) is equal to MOV EAX, DWORD [ES:ESI] LEA ESI, [ESI - 4]