getvec

int getvec(DB_Sample *vector)

Return:

>0

Success; the returned value is the number of input signals (the number of valid entries in vector)

-1

End of data (contents of vector not valid)

-3

Failure: unexpected physical end of file

-4

Failure: checksum error (detected only at end of file)

This function reads a sample from each input signal. The caller should allocate storage for an array of DB_Samples (integers) and pass a pointer to this array to getvec. (The length of the array must be no less than the number of input signals, as obtained from isigopen or dbinit; this number will never exceed DB_MAXSIG, defined in `<ecg/db.h>'.) On return, vector[i] contains the next sample from signal i. For example, this modified version of the example from chapter 1 reads and prints the first ten samples of each available input signal:

#include <ecg/db.h>

main()
{
    int i, j, nsig;
    DB_Sample v[DB_MAXSIG];
    static DB_Siginfo s[DB_MAXSIG];

    nsig = isigopen("100s", s, DB_MAXSIG);
    if (nsig < 1)
        exit(1);
    for (i = 0; i < 10; i++) {
        if (getvec(v) < 0)
            break;
        for (j = 0; j < nsig; j++)
            printf("%8d", v[j]);
        printf("\n");
    }
    exit(0);
}

Notice how the value returned by isigopen is used to determine how many input signals there are. The array of DB_Siginfo structures is declared static, a practice that is recommended for all arrays and data structures of any substantial size, to avoid run-time stack overflow. Several of the example programs in chapter 6 illustrate the use of getvec; for example, see section Example 6: A Differentiator.

Go to the first, previous, next, last section, table of contents.