[SOLVED] populating an array at compile time in C

populating an array at compile time in C

I have some embedded C code where I want to have a list of sine values. I have done something similar in C++ using a constexpr function that return an std::array outside of the main loop:

#include <array>
#include <cmath>

#define sineListSize 100
#define sineListAmp 100

constexpr auto makeSineList() {
    std::array<int, sineListSize> list = {};

    for (int i=0; i<sineListSize; i++) {
        list[i] = sineListAmp * sin(i * 2 * M_PI / sineListSize);
    }

    return list;
}

auto sineList = makeSineList();

The way I've done it now is just the list in a separate header file, because it has 8192 elements and goes up to the signed 32-bit integer limit. It is hard to modify (I have to generate the values and copy them in manually anytime I want to change the parameters of generation) and I have to keep all the parameters in comments. How would I do something like this in C?

Solution

The classic method is you write a program that calculates the values and writes them to output in the format of a C array initialization. As part of your project’s build process, it compiles and runs that program on the build host, directing its output to a header file. That header file is included in your other sources.