static void cirrus_invalidate_region(CirrusVGAState * s, int off_begin,

				     int off_pitch, int bytesperline,

				     int lines)

{

    int y;

    int off_cur;

    int off_cur_end;



    if (off_pitch < 0) {

        off_begin -= bytesperline - 1;

    }



    for (y = 0; y < lines; y++) {

	off_cur = off_begin;

	off_cur_end = (off_cur + bytesperline) & s->cirrus_addr_mask;

        assert(off_cur_end >= off_cur);

        memory_region_set_dirty(&s->vga.vram, off_cur, off_cur_end - off_cur);

	off_begin += off_pitch;

    }

}
