A.5.141 LODSB, LODSW, LODSD: Load from String
LODSB ; AC [8086]
LODSW ; o16 AD [8086]
LODSD ; o32 AD [386]
LODSB loads a byte from [DS:SI] or [DS:ESI] into AL. It then increments
or decrements (depending on the direction flag: increments if the flag
is clear, decrements if it is set) SI or ESI.
The register used is SI if the address size is 16 bits, and ESI if it
is 32 bits. If you need to use an address size not equal to the current
BITS setting, you can use an explicit "a16" or "a32" prefix.
The segment register used to load from [SI] or [ESI] can be overridden
by using a segment register name as a prefix (for example, ES LODSB).
LODSW and LODSD work in the same way, but they load a word or a
doubleword instead of a byte, and increment or decrement the addressing
registers by 2 or 4 instead of 1.
The REP prefix may be used to repeat the instruction CX (or ECX - again,
the address size chooses which) times. The REP alias REPE, as well as
the differently-encoded REPNE, are both allowed as well. They behave in
the same way as REP.