Example Model

Open the InternalZeroInitialization model. The model contains an enabled subsystem whose initial output is zero. The subsystem contains a Unit Delay block whose initial condition is 0.

model = 'InternalZeroInitialization';
open_system(model);

Generate Code Without Optimization

Build the model by using Embedded Coder®.

evalc('slbuild(model)');

This code is in the InternalZeroInitialization.c file.

cfile = fullfile('InternalZeroInitialization_ert_rtw','InternalZeroInitialization.c');
coder.example.extractLines(cfile,'/* Model initialize', '* File trailer', 1, 0);

/* Model initialize function */
void InternalZeroInitialization_initialize(void)
{
  /* Registration code */

  /* initialize error status */
  rtmSetErrorStatus(rtM, (NULL));

  /* states (dwork) */
  (void) memset((void *)&rtDWork, 0,
                sizeof(D_Work));

  /* SystemInitialize for Enabled SubSystem: '<Root>/Enabled Subsystem' */
  /* InitializeConditions for UnitDelay: '<S1>/Unit Delay' */
  rtDWork.UnitDelay_DSTATE = 0.0;

  /* End of SystemInitialize for SubSystem: '<Root>/Enabled Subsystem' */
}

/*

Enable Optimization

Open the Configuration Parameters dialog box. On the Optimization pane, select Remove internal data zero initialization.

Alternatively, you can use the command prompt to enable the optimization. Set the model parameter ZeroInternalMemoryAtStartup to 'off'.

set_param(model, 'ZeroInternalMemoryAtStartup', 'off');

set_param(model, 'ZeroInternalMemoryAtStartup', 'off');

Generate Code with Optimization

Build the model by using Embedded Coder.

evalc('slbuild(model)');

This code is in the InternalZeroInitialization.c file. The generated code does not initialize internal data by assignment to zero.

coder.example.extractLines(cfile,'/* Model initialize', '* File trailer', 1, 0);

/* Model initialize function */
void InternalZeroInitialization_initialize(void)
{
  /* (no initialization code required) */
}

/*

bdclose(model)

Example Model

In the RootZeroInitialization model, all of the input and output signals have a numeric value of zero. Because signals sig1 and sig2 have data types int16 and Boolean, respectively, and all of the output signals have data type double, these signals also have initial values of bitwise zero. The signals have an integer bit pattern of 0, meaning that all bits are off. Signals sig1_b and sig2_b have a fixed-point data type with bias, so their initial value is not bitwise zero.

model = 'RootZeroInitialization';
open_system(model);

Generate Code

% Build the model by using Embedded Coder.
set_param(model, 'ZeroExternalMemoryAtStartup','on');
evalc('slbuild(model)');

These lines of RootZeroInitialization.c code show the initialization of root-level inports and outports without the optimization. The four input signals are individually initialized as global variables. The four output signals are members of a global structure that the memset function initializes to bitwise zero.

cfile = fullfile('RootZeroInitialization_ert_rtw',...
    'RootZeroInitialization.c');
coder.example.extractLines(cfile, '/* Model initialize function */',...
    'trailer for generated code', 1, 0);

/* Model initialize function */
void initialize(void)
{
  /* Registration code */

  /* external inputs */
  sig1 = 0;
  sig2 = false;
  sig1_b = -3;
  sig2_b = -3;

  /* external outputs */
  (void)memset(&rtY, 0, sizeof(ExternalOutputs));
}

/*

Enable Optimization

Alternatively, use the command-line API to enable the optimization:

 set_param(model, 'ZeroExternalMemoryAtStartup','off');

Generate Code with Optimization

The optimized code does not contain initialization code for the input signals sig1, sig2, and the four output signals because their initial values are bitwise zero.

Build the model.

evalc('slbuild(model)');

Here is the RootZeroInitialization.c optimized code in the initialization function.

cfile = fullfile('RootZeroInitialization_ert_rtw',...
    'RootZeroInitialization.c');
coder.example.extractLines(cfile, '/* Model initialize function */',...
    'trailer for generated code', 1, 0);

/* Model initialize function */
void initialize(void)
{
  /* Registration code */

  /* external inputs */
  sig1_b = -3;
  sig2_b = -3;
}

/*

Close the model and the code generation report.

bdclose(model)