Remove Reset and Disable Functions from the Generated Code

This example shows how the code generator removes unreachable (dead code) instances of the reset and disable functions from the generated code for ERT-based systems that include model referencing hierarchies. Optimizing the generated code to remove unreachable code is a requirement for safety-critical systems. This optimization also improves execution speed and reduces ROM consumption.

If a model contains blocks with states, the generated code contains reset and disable functions. If the model is not part of a conditionally executed system, such as an enabled subsystem, the code generator can remove the disable function because the generated code does not call it. If the model is not part of a conditionally executed system that can reset states when a control input enables it, the code generator can remove the reset function because the generated code does not call it.

Example Model

A referenced model, rtwdemo_optionalDisableResetFunc_bot, is in rtwdemo_optionalDisableResetFunc_top. The referenced model contains two blocks with states, a Delay block and a Discrete-Time Integrator block.

Generate Code

Open the models. In the Command Window, type rtwdemo_optionalDisableResetFunc_bot and rtwdemo_optionalDisableResetFunc_top.
In your system temporary folder, create a temporary folder for the build and inspection process.
Build the model.
Open the rtwdemo_optionalDisableResetFunc_top.c and rtwdemo_optionalDisableResetFunc_bot.c files.

The rtwdemo_optionalDisableResetFunc_bot.c file contains these reset and disable functions.

/* System reset for referenced model: 'rtwdemo_optionalDisableResetFunc_bot' */
void rtwdemo_optionalDisableResetFunc_bot_Reset
  (DW_rtwdemo_optionalDisableResetFunc_bot_f_T *localDW)
{
  /* InitializeConditions for Delay: '<Root>/Delay' */
  localDW->Delay_DSTATE = 0.0;

  /* InitializeConditions for DiscreteIntegrator: '<Root>/Discrete-Time Integrator' */
  localDW->DiscreteTimeIntegrator_DSTATE = 3.0;
}

/* Disable for referenced model: 'rtwdemo_optionalDisableResetFunc_bot' */
void rtwdemo_optionalDisableResetFunc_bot_Disable(real_T *rty_Out1,
  DW_rtwdemo_optionalDisableResetFunc_bot_f_T *localDW)
{
  /* Disable for DiscreteIntegrator: '<Root>/Discrete-Time Integrator' */
  localDW->DiscreteTimeIntegrator_DSTATE = *rty_Out1;
}

The rtwdemo_optionalDisableResetFunc_top_step function does not call the rtwdemo_optionalDisableResetFunc_bot_Disable function because the model is not part of a conditionally executed system. The rtwdemo_optionalDisableResetFunc_top_step function does not call the rtwdemo_optionalDisableResetFunc_bot_Reset function because the model is not part of a conditionally executed system that can reset states when a control input enables it.

Enable Optimization

Open the Model Configuration Parameters dialog box for rtwdemo_optionalDisableResetFunc_bot.
Select Remove Disable Function and Remove Reset Function.

Open the rtwdemo_optionalDisableResetFunc_bot.c file. The code does not contain the rtwdemo_optionalDisableResetFunc_bot_Reset function or the rtwdemo_optionalDisableResetFunc_bot_Disable function.

Documentation