While Loop
This example shows how to implement a while loop construct by using Simulink blocks, Stateflow Charts, and MATLAB Function blocks.
C Construct
while(flag && (num_iter <= 100)
{
flag = func ();
num_iter ++;
}
Modeling Pattern for While Loop: While Iterator Subsystem block
One method for creating a while loop is to use a While Iterator Subsystem block from the Simulink > Ports and Subsystems library.
1. Open example model ex_while_loop_SL.
The model contains a While Iterator Subsystem block that repeats execution of the contents of the subsystem during a simulation time step.
Observe the following settings in the model:
The Constant block provides an initial condition to the While Iterator Subsystem. For the Constant block, the Constant value is
1and the Output data type isboolean. The initial condition can be dependent on the input to the block.
In the While Iterator Subsystem, the
funcsubsystem block has an outputflagof0or1depending on the result of the algorithm infunc( ).func()is the Function name infuncsubsystem.
In the While Iterator Subsystem, for the While Iterator block, the Maximum number of iterations is
100.
For the While Iterator block, the While loop type is
while.
2. To build the model and generate code, press Ctrl+B.
The code implementing the while loop is in the ex_while_loop_SL_step function in ex_while_loop_SL.c:
/* Model step function */
void ex_while_loop_SL_step(void)
{
int32_T s1_iter;
boolean_T loopCond;
/* Outputs for Iterator SubSystem: '<Root>/While Iterator Subsystem' incorporates:
* WhileIterator: '<S1>/While Iterator'
*/
s1_iter = 1;
/* SystemReset for Atomic SubSystem: '<S1>/func' */
func_Reset();
/* End of SystemReset for SubSystem: '<S1>/func' */
loopCond = true;
while (loopCond && (s1_iter <= 100)) {
/* Outputs for Atomic SubSystem: '<S1>/func' */
func();
/* End of Outputs for SubSystem: '<S1>/func' */
loopCond = flag;
s1_iter++;
}
/* End of Outputs for SubSystem: '<Root>/While Iterator Subsystem' */
}
Modeling Pattern for While Loop: Stateflow Chart
1. Open example model ex_while_loop_SF.
In the model, the ex_while_loop_SF/Chart executes the while loop.
The chart contains a While loop decision pattern that you add by right clicking inside the chart > Add Pattern in Chart > Loop > While.
2. To build the model and generate code, press Ctrl+B.
The code implementing the while loop is in the ex_while_loop_SF_step function in ex_while_loop_SF.c:
/* Model step function */
void ex_while_loop_SF_step(void)
{
/* Chart: '<Root>/Chart' */
num_iter = 1;
while (flag && (num_iter <= 100)) {
/* Outputs for Function Call SubSystem: '<Root>/func' */
func();
/* End of Outputs for SubSystem: '<Root>/func' */
num_iter++;
}
/* End of Chart: '<Root>/Chart' */
}
Modeling Pattern for For Loop: MATLAB Function block
1. Open example model ex_while_loop_ML.
The MATLAB Function Block contains this function:
function fcn(func_flag) flag = true; num_iter = 1; while(flag && (num_iter<=100)) func; flag = func_flag; num_iter = num_iter + 1; end
2. To build the model and generate code, press Ctrl+B.
The code implementing the while loop is in the ex_while_loop_ML_step function in ex_while_loop_ML.c:
/* Model step function */
void ex_while_loop_ML_step(void)
{
int32_T num_iter;
boolean_T flag;
boolean_T func_flag_0;
/* MATLAB Function: '<Root>/MATLAB Function' */
func_flag_0 = func_flag;
flag = true;
num_iter = 1;
while (flag && (num_iter <= 100)) {
/* Outputs for Function Call SubSystem: '<Root>/func' */
func();
/* End of Outputs for SubSystem: '<Root>/func' */
flag = func_flag_0;
num_iter++;
}
/* End of MATLAB Function: '<Root>/MATLAB Function' */
}