GRC_WINDOW_SIZE
grc_win_offset = reg_offset & (GRC_WINDOW_SIZE - 1);
grc_win_base = reg_offset & ~(GRC_WINDOW_SIZE - 1);
if(grc_win_offset >= GRC_WINDOW_SIZE)
grc_win_base += GRC_WINDOW_SIZE;
grc_win_size = GRC_WINDOW_SIZE / 4;
grc_win_size = GRC_WINDOW_SIZE;