AARCH64_INSN_IMM_16
sys_reg = (u32)aarch64_insn_decode_immediate(AARCH64_INSN_IMM_16, insn) << 5;
insn = aarch64_insn_encode_immediate(AARCH64_INSN_IMM_16, insn, imm);
case AARCH64_INSN_IMM_16:
return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_16, insn, imm);