Rectangle copy

main.c

static void copy_rect(char* buffer_src, int pitch_a,
                      char* buffer_dst, int pitch_b,
                      int from_min_x, int from_min_y,
                      int from_max_x, int from_max_y,
                      int to_min_x, int to_min_y)
{
    char* src = buffer_src + from_min_y * pitch_a + from_min_x;
    char* dst = buffer_dst + to_min_y   * pitch_b + to_min_x;

    int width  = from_max_x - from_min_x;
    int height = from_max_y - from_min_y;

    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            dst[x] = src[x];
        }

        src += pitch_a;
        dst += pitch_b;
    }
}