ASM_FMT_I6
op = ASM_OP_PSHR2_U, fmt = ASM_FMT_I6;
op = ASM_OP_PSHR2_, fmt = ASM_FMT_I6;
op = ASM_OP_PSHR4_U, fmt = ASM_FMT_I6;
op = ASM_OP_PSHR4_, fmt = ASM_FMT_I6;
case ASM_FMT_I6: