in-place interleave and memmove

void deinterleave_mm(int *a, int len)
{
    for (int i = 1; i < len/2; i++)
    {
        // move a left int into place
        int t = a[i*2];
        memmove(&a[i+1], &a[i], i * sizeof(int));
        a[i] = t;
    }
}

void interleave_mm(int *a, int len)
{
    for (int i = len/2-1; i > 0; i--)
    {
        // move a left int into place
        int t = a[i];
        memmove(&a[i], &a[i+1], i * sizeof(int));
        a[i*2] = t;
    }
}