How to clear custom c-code variables from memory between simulation runs?

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Aleksi Martikainen
Aleksi Martikainen 2018-3-28
回答： Pawel Hanczur 2022-9-12
Hello
I have a Simulink model that has lots of custom c-code functions in it. It seems that in Simulink the custom code variables stay in the memory after the simulation has ended.
For example I have following code:
int i = 0;
int foo() {
i = i + 1;
return i;
}
The value of i does not reset to 0 between simulation runs. The value of i increments by 1 for everytime I run the simulation.
How do I unload the variables of custom c-code from the memory?
Thanks in advance.

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回答（3 个）

Birdman
Birdman 2018-3-28
You can use StartFcn and StopFcn callbacks in File->Model Properties->Model Properties->Callbacks to add and delete custom C code.
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Birdman
Birdman 2018-3-28
In my code, i is defined within the function and at every simulation, it is initialized to 0, equivalent to clearing it at the end of the simulation.
Aleksi Martikainen
Aleksi Martikainen 2018-3-28
Yes, I can see that. But if the function test() is called 100 times during one simulation run, your code would always return 1.
What I want, is that if the function test() is called 100 times during one simulation run, it would return 1, 2, 3, ..., 99, 100.
The original code does excactly that. The problem is, when I run the simulation again, instead of starting from 0 (what I want), it starts counting where the previous simulation ended.
That is why I want to clear the variables after the simulation has ended, not every time I call the function.

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Adam Johnson
Adam Johnson 2022-2-2
Has this question be addressed? I am getting the same issue and need a fix.
Pawel Hanczur
Pawel Hanczur 2022-9-12
Hello.
I was struggling a lot with this strange issue. Here is the workaround:
In m-function you'll should have the contruction of sort fo this:
persistent Is_First_Cycle;
if isempty(Is_First_Cycle)
Is_First_Cycle=1;
else
Is_First_Cycle=0;
end
Then you pass the flag to the to the C code:
coder.ceval('my_C_prg', Is_First_Cycle,...);
Then in C code you can add something like this:
//my_C_prg.c
void C_prg(double Is_First_Cycle, ...)
{
double var1;
double* refVar1;
double* refVar2;
if (Is_First_Cycle==1)
{var1=0;
VarsIni (&refVar1, &refVar2,...);
}
...
What moreover when i was trying to set pointer variable in main function for example:
void C_prg(double Is_First_Cycle,..., ..., ...)
{
double var1;
double* refVar1;
double* refVar2;
if (Is_First_Cycle==1)
{var1=0;
refVar1[0]=1;
refVar2[0]=3;
}
}
The all Matlab crashed. And funny thing is that, that when you I used the first construction (with inner VarsIni function), everything worked fine.
Best regards.

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