Question

I need to store a struct in a file and read it back to return it then.
I would try to write it to the file like this:

void lld_tpWriteCalibration(struct cal cal) {
    FIL fdst;      /* file objects */
   UINT bw;        /* File write count */

    /* Create destination file on the drive 0 */
    wf_open(&fdst, "0:calibration.txt", FA_CREATE_ALWAYS | FA_WRITE);
    wf_write(&fdst, cal, sizeof(cal), &bw);

    wf_close(&fdst);
}

Would that work?
And how can I read it back and return it from this function?

struct cal lld_tpReadCalibration(void) {

}

The struct is:

   struct cal {
       float xm; 
       float ym; 
       float xn; 
       float yn; 
   };

Thanks for your help.

Answer 1

You can retrieve your structure the same way you stored it.

read(&fdst, &cal, sizeof(cal));

But you got to be careful, you won’t be able to do this on every architecture because of endianess problem.