FBT_REG_I0
*tinstr++ = FBT_MOV(FBT_REG_I0, FBT_REG_O1);
*tinstr++ = FBT_MOV(FBT_REG_I0, FBT_REG_O2);
uint32_t rs1, rs2, o2i = FBT_REG_I0 - FBT_REG_O0;
*tinstr++ = FBT_MOV(FBT_REG_I0, FBT_REG_O2);