coder.read

Create a 100-by-100 array of type double in your workspace.

data = rand(100);

Store this variable in a file named exampleData.coderdata in the current folder.

coder.write('myfile.coderdata',data);

Wrote file 'myfile.coderdata'. You can read this file with 'coder.read'.

To read from a .coderdata file with the constant file name exampleData, use the coder.read function syntax that has a single input argument.

function y = my_entry_point(x) %#codegen
dataOut = coder.read('myfile.coderdata');
y = x + mean(dataOut,"all");
end

Generate a MEX function my_entry_point_mex and then call the generated MEX by running these commands:

codegen my_entry_point -args {0}
my_entry_point_mex(1)

Code generation successful.

ans =

    1.4996

You can now update the data stored in myfile.coderdata to a different 100-by-100 array of type double. If you then call my_entry_point_mex that you already generated, the MEX now reads and uses the new data.

d = rand(100) - 1;
coder.write('myfile.coderdata',d);
my_entry_point_mex(1)

Wrote file 'myfile.coderdata'. You can read this file with 'coder.read'.

ans =

    0.4963

To start, create the storage files that you want the generated code to read. At the command line, create variables var_a and var_b that are both of type double but have different sizes. Use the coder.write function to store array var_a and array var_b in the files file_a.coderdata and file_b.coderdata, respectively.

var_a = rand(10,20);
var_b = rand(5,30);
coder.write("file_a.coderdata",var_a)
coder.write("file_b.coderdata",var_b)

Wrote file 'file_a.coderdata'. You can read this file with 'coder.read'.
Wrote file 'file_b.coderdata'. You can read this file with 'coder.read'.

A coder.Type object that is consistent with both variables var_a and var_b must have variable-size dimensions. The upper bounds of the two array dimensions must be at least 10 and 30, respectively. Create a coder.Type object that represents a variable-size type double with these bounds.

t = coder.typeof(var_a,[10 30],[1 1])

t = 

coder.PrimitiveType
   :10×:30 double

Modify the header information of file_a.coderdata to be compatible with both arrays var_a and var_b. You can use the modified file as your desired common type header file.

coder.write("file_a.coderdata",a,TypeHeader=t);

Wrote file 'file_a.coderdata'. You can read this file with 'coder.read'.

Create a MATLAB entry-point function readMultipleFiles that can read file_a.coderdata and file_b.coderdata.

function data = readMultipleFiles(filename) %#codegen
data = coder.read(filename,TypeHeaderFrom="file_a.coderdata");
end

Generate a MEX function for readMultipleFiles. Specify the input argument type as an unbounded variable-size character vector so that it can represent file names of arbitrary length.

codegen readMultipleFiles -args {coder.typeof('a',[1 inf])} -report

Code generation successful: View report

Run the generated MEX function with inputs 'file_a.coderdata' and 'file_b.coderdata'.

readMultipleFiles_mex('file_a.coderdata');
readMultipleFiles_mex('file_b.coderdata');