Load Register Byte (unscaled).
Is the 32-bit name of the general-purpose register to be transferred.
Is the 64-bit name of the general-purpose base register or stack pointer.
Is the optional signed immediate byte offset, in the range -256 to 255, defaulting to 0.
Load Register Byte (unscaled) calculates an address from a base register and an immediate offset, loads a byte from memory, zero-extends it, and writes it to a register. For information about memory accesses, see Load/Store addressing modes in the ARMv8-A Architecture Reference Manual.