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How to initialize a string variable, and pass it to the matlab function using GPU coder

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How to initialize a string in custom main.cu file and pass it to the matlab function using GPU coder? I tried to look into Matlab documentation, I could not find any references. i hope any of the experts help.
i try to compile the Nivida exectuable file using the matlab function,
function out = test_predict(img,SS)
%SS is a string type e.g. SS="ABCD";
persistent mynet1;
persistent mynet2;
if (strncmp(SS,"GR1",2)==true) && isempty(mynet1)
a1='DLmodel1.mat';
mynet1 = coder.loadDeepLearningNetwork(a1);
out=predict(mynet1,img);
else
a2='DLmodel2.mat';
mynet2 = coder.loadDeepLearningNetwork(a2);
out=predict(mynet2,img);
end
The example main.cu file is created as below:
...
// Function Declarations
static void argInit_1x4_char_T(char result[4]);
static void argInit_299x299x3_real32_T(float result[268203]);
static char argInit_char_T();
static float argInit_real32_T();
static coder::rtString argInit_rtString();
static void main_test_predict();
// Function Definitions
static void argInit_1x4_char_T(char result[4])
{
// Loop over the array to initialize each element.
for (int idx1{0}; idx1 < 4; idx1++) {
// Set the value of the array element.
// Change this value to the value that the application requires.
result[idx1] = argInit_char_T();
}
}
static void argInit_299x299x3_real32_T(float result[268203])
{
// Loop over the array to initialize each element.
for (int idx0{0}; idx0 < 299; idx0++) {
for (int idx1{0}; idx1 < 299; idx1++) {
for (int idx2{0}; idx2 < 3; idx2++) {
// Set the value of the array element.
// Change this value to the value that the application requires.
result[(idx0 + 299 * idx1) + 89401 * idx2] = argInit_real32_T();
}
}
}
}
static char argInit_char_T()
{
return '?';
}
static float argInit_real32_T()
{
return 0.0F;
}
static coder::rtString argInit_rtString()
{
coder::rtString result;
// Set the value of each structure field.
// Change this value to the value that the application requires.
argInit_1x4_char_T(result.Value);
return result;
}
static void main_test_predict()
{
static float b[268203];
coder::rtString c;
float out_data[28];
int out_size[2];
argInit_299x299x3_real32_T(b);
c = argInit_rtString();
testdefclass_predict(b, &c, out_data, out_size);
}
int main(int, char **)
{
// The initialize function is being called automatically from your entry-point
// function. So, a call to initialize is not included here. Invoke the
// entry-point functions.
// You can call entry-point functions multiple times.
//SS is a variable and read out from a text file
FILE *fp= fopen('flile1.txt',r);
char SS[5]="ABCD";
main_test_predict();
// Terminate the application.
// You do not need to do this more than one time.
test_predict_terminate();
return 0;
}
// End of code generation (main.cu)
Can you please

Accepted Answer

Joss Knight
Joss Knight on 14 Nov 2022
Edited: Joss Knight on 14 Nov 2022
MATLAB and Simulink code generation do not currently support string.
Edit: Sorry, my bad, it does support scalar strings, but not string arrays.

More Answers (2)

Hariprasad Ravishankar
Hariprasad Ravishankar on 11 Nov 2022
Hi Liwei,
Do you really need a string data type here? Usually its easier to work with char datatype as input to an entry point function.
For example, for the following entry point function
function out = foo(in)
out = strcmp(in,"apple");
end
>> codegen foo -args {'mango'} -config:dll
Coder generates:
boolean_T foo(const char in[5])
And you can pass a char array as input to the entry point:
void main_foo(void)
{
char cv[5];
boolean_T out;
/* Initialize function 'foo' input arguments. */
/* Initialize function input argument 'in'. */
/* Call the entry-point 'foo'. */
argInit_1x5_char_T(cv);
out = foo(cv);
}
Further, if you know that the input will be a constant at codegen time and won't change at runtime, you can specify it as a constant using the codegen command:
>> codegen foo -args {coder.Constant('mango')} -config:dll
This way you will not have to pass it as input to the generated function from your main()

Liwei
Liwei on 11 Nov 2022
Edited: Walter Roberson on 11 Nov 2022
Thank you. "passing char" suggestion helps. can you give a clue how to intialize the char? Is this the correct way below?
static void argInit_1x4_char_T(char result[4],char SS[4])
{
// Loop over the array to initialize each element.
for (int idx1{0}; idx1 < 4; idx1++) {
// Set the value of the array element.
// Change this value to the value that the application requires.
result[idx1] = SS[idx1];
}
}
  3 Comments
Liwei
Liwei on 11 Nov 2022
thanks for the question.
SS and results, i defined them as the same type in main.cu. Not sure how to intialize them in static void argInit_1x4_char_T(char result[4],char SS[4]). Can you show how you want to use memcpy()?

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