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Write and Read Fixed-Point Data

The dsp.BinaryFileWriter and dsp.BinaryFileReader System objects do not support writing and reading fixed-point data. As a workaround, you can write the stored integer portion of the fi data, read the data, and use this value to reconstruct the fi data.

Write the Fixed-Point Data

Create an fi object to represent 100 signed random numbers with a word length of 14 and a fraction length of 12. Write the stored integer portion of the fi object to the data file myFile.dat. The built-in data type is int16, which can be computed using class(storeIntData).

data = randn(100,1);
fiDataWriter = fi(data,1,14,12);
storeIntData = storedInteger(fiDataWriter);

writer = dsp.BinaryFileWriter('myFile.dat');

Release the writer so that the reader can access the data.


Read the Fixed-Point Data

Specify the reader to read the stored integer data as int16 data with 100 samples per data frame. The real-world value of the fixed-point number can be represented using 2(-fractionLength)(storedInteger). If you know the signedness, word length, and fraction length of the fixed-point data, you can reconstruct the fi data using fi(realValue,signedness,wordLength,fractionLength). In this example, the data is signed with a word length of 14 and a fraction length of 12.

reader = dsp.BinaryFileReader('Filename','myFile.dat',...
data = reader();
fractionLength = 12;
wordLength = 14;
realValue = 2^(-fractionLength)*double(data);

fiDataReader = fi(realValue,1,...

Verify that the writer data is the same as the reader data.

ans = logical

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