/**
 * @file lv_refr.c
 *
 */

/*********************
 *      INCLUDES
 *********************/
#include <stddef.h>
#include "lv_refr.h"
#include "lv_disp.h"
#include "../lv_hal/lv_hal_tick.h"
#include "../lv_hal/lv_hal_disp.h"
#include "../lv_misc/lv_task.h"
#include "../lv_misc/lv_mem.h"
#include "../lv_misc/lv_math.h"
#include "../lv_misc/lv_gc.h"
#include "../lv_draw/lv_draw.h"
#include "../lv_font/lv_font_fmt_txt.h"

#if LV_USE_PERF_MONITOR
    #include "../lv_widgets/lv_label.h"
#endif

#if defined(LV_GC_INCLUDE)
    #include LV_GC_INCLUDE
#endif /* LV_ENABLE_GC */

/*********************
 *      DEFINES
 *********************/
/* Draw translucent random colored areas on the invalidated (redrawn) areas*/
#define MASK_AREA_DEBUG 0

/**********************
 *      TYPEDEFS
 **********************/

/**********************
 *  STATIC PROTOTYPES
 **********************/
static void lv_refr_join_area(void);
static void lv_refr_areas(void);
static void lv_refr_area(const lv_area_t * area_p);
static void lv_refr_area_part(const lv_area_t * area_p);
static lv_obj_t * lv_refr_get_top_obj(const lv_area_t * area_p, lv_obj_t * obj);
static void lv_refr_obj_and_children(lv_obj_t * top_p, const lv_area_t * mask_p);
static void lv_refr_obj(lv_obj_t * obj, const lv_area_t * mask_ori_p);
static void lv_refr_vdb_flush(void);

/**********************
 *  STATIC VARIABLES
 **********************/
static uint32_t px_num;
static lv_disp_t * disp_refr; /*Display being refreshed*/

/**********************
 *      MACROS
 **********************/

/**********************
 *   GLOBAL FUNCTIONS
 **********************/

/**
 * Initialize the screen refresh subsystem
 */
void _lv_refr_init(void)
{
    /*Nothing to do*/
}

/**
 * Redraw the invalidated areas now.
 * Normally the redrawing is periodically executed in `lv_task_handler` but a long blocking process
 * can prevent the call of `lv_task_handler`. In this case if the the GUI is updated in the process
 * (e.g. progress bar) this function can be called when the screen should be updated.
 * @param disp pointer to display to refresh. NULL to refresh all displays.
 */
void lv_refr_now(lv_disp_t * disp)
{
#if LV_USE_ANIMATION
    lv_anim_refr_now();
#endif

    if(disp) {
        _lv_disp_refr_task(disp->refr_task);
    }
    else {
        lv_disp_t * d;
        d = lv_disp_get_next(NULL);
        while(d) {
            _lv_disp_refr_task(d->refr_task);
            d = lv_disp_get_next(d);
        }
    }
}

/**
 * Invalidate an area on display to redraw it
 * @param area_p pointer to area which should be invalidated (NULL: delete the invalidated areas)
 * @param disp pointer to display where the area should be invalidated (NULL can be used if there is
 * only one display)
 */
void _lv_inv_area(lv_disp_t * disp, const lv_area_t * area_p)
{
    if(!disp) disp = lv_disp_get_default();
    if(!disp) return;

    /*Clear the invalidate buffer if the parameter is NULL*/
    if(area_p == NULL) {
        disp->inv_p = 0;
        return;
    }

    lv_area_t scr_area;
    scr_area.x1 = 0;
    scr_area.y1 = 0;
    scr_area.x2 = lv_disp_get_hor_res(disp) - 1;
    scr_area.y2 = lv_disp_get_ver_res(disp) - 1;

    lv_area_t com_area;
    bool suc;

    suc = _lv_area_intersect(&com_area, area_p, &scr_area);

    /*The area is truncated to the screen*/
    if(suc != false) {
        if(disp->driver.rounder_cb) disp->driver.rounder_cb(&disp->driver, &com_area);

        /*Save only if this area is not in one of the saved areas*/
        uint16_t i;
        for(i = 0; i < disp->inv_p; i++) {
            if(_lv_area_is_in(&com_area, &disp->inv_areas[i], 0) != false) return;
        }

        /*Save the area*/
        if(disp->inv_p < LV_INV_BUF_SIZE) {
            lv_area_copy(&disp->inv_areas[disp->inv_p], &com_area);
        }
        else {   /*If no place for the area add the screen*/
            disp->inv_p = 0;
            lv_area_copy(&disp->inv_areas[disp->inv_p], &scr_area);
        }
        disp->inv_p++;
        lv_task_set_prio(disp->refr_task, LV_REFR_TASK_PRIO);
    }
}

/**
 * Get the display which is being refreshed
 * @return the display being refreshed
 */
lv_disp_t * _lv_refr_get_disp_refreshing(void)
{
    return disp_refr;
}

/**
 * Set the display which is being refreshed.
 * It shouldn1t be used directly by the user.
 * It can be used to trick the drawing functions about there is an active display.
 * @param the display being refreshed
 */
void _lv_refr_set_disp_refreshing(lv_disp_t * disp)
{
    disp_refr = disp;
}

/**
 * Called periodically to handle the refreshing
 * @param task pointer to the task itself
 */
void _lv_disp_refr_task(lv_task_t * task)
{
    LV_LOG_TRACE("lv_refr_task: started");

    uint32_t start = lv_tick_get();
    uint32_t elaps = 0;

    disp_refr = task->user_data;

#if LV_USE_PERF_MONITOR == 0
    /* Ensure the task does not run again automatically.
     * This is done before refreshing in case refreshing invalidates something else.
     */
    lv_task_set_prio(task, LV_TASK_PRIO_OFF);
#endif

    /*Do nothing if there is no active screen*/
    if(disp_refr->act_scr == NULL) {
        disp_refr->inv_p = 0;
        return;
    }

    lv_refr_join_area();

    lv_refr_areas();

    /*If refresh happened ...*/
    if(disp_refr->inv_p != 0) {
        /* In true double buffered mode copy the refreshed areas to the new VDB to keep it up to date.
         * With set_px_cb we don't know anything about the buffer (even it's size) so skip copying.*/
        if(lv_disp_is_true_double_buf(disp_refr) && disp_refr->driver.set_px_cb == NULL) {
            lv_disp_buf_t * vdb = lv_disp_get_buf(disp_refr);

            /*Flush the content of the VDB*/
            lv_refr_vdb_flush();

            /* With true double buffering the flushing should be only the address change of the
             * current frame buffer. Wait until the address change is ready and copy the changed
             * content to the other frame buffer (new active VDB) to keep the buffers synchronized*/
            while(vdb->flushing)
                ;

            uint8_t * buf_act = (uint8_t *)vdb->buf_act;
            uint8_t * buf_ina = (uint8_t *)vdb->buf_act == vdb->buf1 ? vdb->buf2 : vdb->buf1;

            lv_coord_t hres = lv_disp_get_hor_res(disp_refr);
            uint16_t a;
            for(a = 0; a < disp_refr->inv_p; a++) {
                if(disp_refr->inv_area_joined[a] == 0) {
                    lv_coord_t y;
                    uint32_t start_offs =
                        (hres * disp_refr->inv_areas[a].y1 + disp_refr->inv_areas[a].x1) * sizeof(lv_color_t);
                    uint32_t line_length = lv_area_get_width(&disp_refr->inv_areas[a]) * sizeof(lv_color_t);

                    for(y = disp_refr->inv_areas[a].y1; y <= disp_refr->inv_areas[a].y2; y++) {
                        _lv_memcpy(buf_act + start_offs, buf_ina + start_offs, line_length);
                        start_offs += hres * sizeof(lv_color_t);
                    }
                }
            }
        } /*End of true double buffer handling*/

        /*Clean up*/
        _lv_memset_00(disp_refr->inv_areas, sizeof(disp_refr->inv_areas));
        _lv_memset_00(disp_refr->inv_area_joined, sizeof(disp_refr->inv_area_joined));
        disp_refr->inv_p = 0;

        elaps = lv_tick_elaps(start);
        /*Call monitor cb if present*/
        if(disp_refr->driver.monitor_cb) {
            disp_refr->driver.monitor_cb(&disp_refr->driver, elaps, px_num);
        }
    }

    _lv_mem_buf_free_all();
    _lv_font_clean_up_fmt_txt();

#if LV_USE_PERF_MONITOR && LV_USE_LABEL
    static lv_obj_t * perf_label = NULL;
    if(perf_label == NULL) {
        perf_label = lv_label_create(lv_layer_sys(), NULL);
        lv_label_set_align(perf_label, LV_LABEL_ALIGN_RIGHT);
        lv_obj_set_style_local_bg_opa(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_COVER);
        lv_obj_set_style_local_bg_color(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_BLACK);
        lv_obj_set_style_local_text_color(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_WHITE);
        lv_obj_set_style_local_pad_top(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, 3);
        lv_obj_set_style_local_pad_bottom(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, 3);
        lv_obj_set_style_local_pad_left(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, 3);
        lv_obj_set_style_local_pad_right(perf_label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, 3);
        lv_label_set_text(perf_label, "?");
        lv_obj_align(perf_label, NULL, LV_ALIGN_IN_BOTTOM_RIGHT, 0, 0);
    }

    static uint32_t perf_last_time = 0;
    static uint32_t elaps_max = 1;
    if(lv_tick_elaps(perf_last_time) < 300) {
        elaps_max = LV_MATH_MAX(elaps, elaps_max);
    }
    else {
        perf_last_time = lv_tick_get();
        uint32_t fps = 1000 / (elaps_max == 0 ? 1 : elaps_max);
        elaps_max = 1;
        uint32_t fps_limit = 1000 / disp_refr->refr_task->period;
        if(fps > fps_limit) fps = fps_limit;

        uint32_t cpu = 100 - lv_task_get_idle();
        lv_label_set_text_fmt(perf_label, "%d FPS\n%d%% CPU", fps, cpu);
        lv_obj_align(perf_label, NULL, LV_ALIGN_IN_BOTTOM_RIGHT, 0, 0);
    }
#endif

    LV_LOG_TRACE("lv_refr_task: ready");
}

/**********************
 *   STATIC FUNCTIONS
 **********************/

/**
 * Join the areas which has got common parts
 */
static void lv_refr_join_area(void)
{
    uint32_t join_from;
    uint32_t join_in;
    lv_area_t joined_area;
    for(join_in = 0; join_in < disp_refr->inv_p; join_in++) {
        if(disp_refr->inv_area_joined[join_in] != 0) continue;

        /*Check all areas to join them in 'join_in'*/
        for(join_from = 0; join_from < disp_refr->inv_p; join_from++) {
            /*Handle only unjoined areas and ignore itself*/
            if(disp_refr->inv_area_joined[join_from] != 0 || join_in == join_from) {
                continue;
            }

            /*Check if the areas are on each other*/
            if(_lv_area_is_on(&disp_refr->inv_areas[join_in], &disp_refr->inv_areas[join_from]) == false) {
                continue;
            }

            _lv_area_join(&joined_area, &disp_refr->inv_areas[join_in], &disp_refr->inv_areas[join_from]);

            /*Join two area only if the joined area size is smaller*/
            if(lv_area_get_size(&joined_area) < (lv_area_get_size(&disp_refr->inv_areas[join_in]) +
                                                 lv_area_get_size(&disp_refr->inv_areas[join_from]))) {
                lv_area_copy(&disp_refr->inv_areas[join_in], &joined_area);

                /*Mark 'join_form' is joined into 'join_in'*/
                disp_refr->inv_area_joined[join_from] = 1;
            }
        }
    }
}

/**
 * Refresh the joined areas
 */
static void lv_refr_areas(void)
{
    px_num = 0;

    if(disp_refr->inv_p == 0) return;

    /*Find the last area which will be drawn*/
    int32_t i;
    int32_t last_i = 0;
    for(i = disp_refr->inv_p - 1; i >= 0; i--) {
        if(disp_refr->inv_area_joined[i] == 0) {
            last_i = i;
            break;
        }
    }

    disp_refr->driver.buffer->last_area = 0;
    disp_refr->driver.buffer->last_part = 0;

    for(i = 0; i < disp_refr->inv_p; i++) {
        /*Refresh the unjoined areas*/
        if(disp_refr->inv_area_joined[i] == 0) {

            if(i == last_i) disp_refr->driver.buffer->last_area = 1;
            disp_refr->driver.buffer->last_part = 0;
            lv_refr_area(&disp_refr->inv_areas[i]);

            if(disp_refr->driver.monitor_cb) px_num += lv_area_get_size(&disp_refr->inv_areas[i]);
        }
    }
}

/**
 * Refresh an area if there is Virtual Display Buffer
 * @param area_p  pointer to an area to refresh
 */
static void lv_refr_area(const lv_area_t * area_p)
{
    /*True double buffering: there are two screen sized buffers. Just redraw directly into a
     * buffer*/
    if(lv_disp_is_true_double_buf(disp_refr)) {
        lv_disp_buf_t * vdb = lv_disp_get_buf(disp_refr);
        vdb->area.x1        = 0;
        vdb->area.x2        = lv_disp_get_hor_res(disp_refr) - 1;
        vdb->area.y1        = 0;
        vdb->area.y2        = lv_disp_get_ver_res(disp_refr) - 1;
        disp_refr->driver.buffer->last_part = 1;
        lv_refr_area_part(area_p);
    }
    /*The buffer is smaller: refresh the area in parts*/
    else {
        lv_disp_buf_t * vdb = lv_disp_get_buf(disp_refr);
        /*Calculate the max row num*/
        lv_coord_t w = lv_area_get_width(area_p);
        lv_coord_t h = lv_area_get_height(area_p);
        lv_coord_t y2 =
            area_p->y2 >= lv_disp_get_ver_res(disp_refr) ? lv_disp_get_ver_res(disp_refr) - 1 : area_p->y2;

        int32_t max_row = (uint32_t)vdb->size / w;

        if(max_row > h) max_row = h;

        /*Round down the lines of VDB if rounding is added*/
        if(disp_refr->driver.rounder_cb) {
            lv_area_t tmp;
            tmp.x1 = 0;
            tmp.x2 = 0;
            tmp.y1 = 0;

            lv_coord_t h_tmp = max_row;
            do {
                tmp.y2 = h_tmp - 1;
                disp_refr->driver.rounder_cb(&disp_refr->driver, &tmp);

                /*If this height fits into `max_row` then fine*/
                if(lv_area_get_height(&tmp) <= max_row) break;

                /*Decrement the height of the area until it fits into `max_row` after rounding*/
                h_tmp--;
            } while(h_tmp > 0);

            if(h_tmp <= 0) {
                LV_LOG_WARN("Can't set VDB height using the round function. (Wrong round_cb or to "
                            "small VDB)");
                return;
            }
            else {
                max_row = tmp.y2 + 1;
            }
        }

        /*Always use the full row*/
        lv_coord_t row;
        lv_coord_t row_last = 0;
        for(row = area_p->y1; row + max_row - 1 <= y2; row += max_row) {
            /*Calc. the next y coordinates of VDB*/
            vdb->area.x1 = area_p->x1;
            vdb->area.x2 = area_p->x2;
            vdb->area.y1 = row;
            vdb->area.y2 = row + max_row - 1;
            if(vdb->area.y2 > y2) vdb->area.y2 = y2;
            row_last = vdb->area.y2;
            if(y2 == row_last) disp_refr->driver.buffer->last_part = 1;
            lv_refr_area_part(area_p);
        }

        /*If the last y coordinates are not handled yet ...*/
        if(y2 != row_last) {
            /*Calc. the next y coordinates of VDB*/
            vdb->area.x1 = area_p->x1;
            vdb->area.x2 = area_p->x2;
            vdb->area.y1 = row;
            vdb->area.y2 = y2;

            disp_refr->driver.buffer->last_part = 1;
            lv_refr_area_part(area_p);
        }
    }
}

/**
 * Refresh a part of an area which is on the actual Virtual Display Buffer
 * @param area_p pointer to an area to refresh
 */
static void lv_refr_area_part(const lv_area_t * area_p)
{
    lv_disp_buf_t * vdb = lv_disp_get_buf(disp_refr);

    /*In non double buffered mode, before rendering the next part wait until the previous image is
     * flushed*/
    if(lv_disp_is_double_buf(disp_refr) == false) {
        while(vdb->flushing) {
            if(disp_refr->driver.wait_cb) disp_refr->driver.wait_cb(&disp_refr->driver);
        }
    }

    lv_obj_t * top_p;

    /*Get the new mask from the original area and the act. VDB
     It will be a part of 'area_p'*/
    lv_area_t start_mask;
    _lv_area_intersect(&start_mask, area_p, &vdb->area);

    /*Get the most top object which is not covered by others*/
    top_p = lv_refr_get_top_obj(&start_mask, lv_disp_get_scr_act(disp_refr));

    /*Do the refreshing from the top object*/
    lv_refr_obj_and_children(top_p, &start_mask);

    /*Also refresh top and sys layer unconditionally*/
    lv_refr_obj_and_children(lv_disp_get_layer_top(disp_refr), &start_mask);
    lv_refr_obj_and_children(lv_disp_get_layer_sys(disp_refr), &start_mask);

    /* In true double buffered mode flush only once when all areas were rendered.
     * In normal mode flush after every area */
    if(lv_disp_is_true_double_buf(disp_refr) == false) {
        lv_refr_vdb_flush();
    }
}

/**
 * Search the most top object which fully covers an area
 * @param area_p pointer to an area
 * @param obj the first object to start the searching (typically a screen)
 * @return
 */
static lv_obj_t * lv_refr_get_top_obj(const lv_area_t * area_p, lv_obj_t * obj)
{
    lv_obj_t * found_p = NULL;

    /*If this object is fully cover the draw area check the children too */
    if(_lv_area_is_in(area_p, &obj->coords, 0) && obj->hidden == 0) {
        lv_design_res_t design_res = obj->design_cb ? obj->design_cb(obj, area_p,
                                                                     LV_DESIGN_COVER_CHK) : LV_DESIGN_RES_NOT_COVER;
        if(design_res == LV_DESIGN_RES_MASKED) return NULL;

        lv_obj_t * i;
        _LV_LL_READ(obj->child_ll, i) {
            found_p = lv_refr_get_top_obj(area_p, i);

            /*If a children is ok then break*/
            if(found_p != NULL) {
                break;
            }
        }

        /*If no better children use this object*/
        if(found_p == NULL) {
            if(design_res == LV_DESIGN_RES_COVER) {
                found_p = obj;
            }
        }
    }

    return found_p;
}

/**
 * Make the refreshing from an object. Draw all its children and the youngers too.
 * @param top_p pointer to an objects. Start the drawing from it.
 * @param mask_p pointer to an area, the objects will be drawn only here
 */
static void lv_refr_obj_and_children(lv_obj_t * top_p, const lv_area_t * mask_p)
{
    /* Normally always will be a top_obj (at least the screen)
     * but in special cases (e.g. if the screen has alpha) it won't.
     * In this case use the screen directly */
    if(top_p == NULL) top_p = lv_disp_get_scr_act(disp_refr);
    if(top_p == NULL) return;  /*Shouldn't happen*/

    /*Refresh the top object and its children*/
    lv_refr_obj(top_p, mask_p);

    /*Draw the 'younger' sibling objects because they can be on top_obj */
    lv_obj_t * par;
    lv_obj_t * border_p = top_p;

    par = lv_obj_get_parent(top_p);

    /*Do until not reach the screen*/
    while(par != NULL) {
        /*object before border_p has to be redrawn*/
        lv_obj_t * i = _lv_ll_get_prev(&(par->child_ll), border_p);

        while(i != NULL) {
            /*Refresh the objects*/
            lv_refr_obj(i, mask_p);
            i = _lv_ll_get_prev(&(par->child_ll), i);
        }

        /*Call the post draw design function of the parents of the to object*/
        if(par->design_cb) par->design_cb(par, mask_p, LV_DESIGN_DRAW_POST);

        /*The new border will be there last parents,
         *so the 'younger' brothers of parent will be refreshed*/
        border_p = par;
        /*Go a level deeper*/
        par = lv_obj_get_parent(par);
    }
}

/**
 * Refresh an object an all of its children. (Called recursively)
 * @param obj pointer to an object to refresh
 * @param mask_ori_p pointer to an area, the objects will be drawn only here
 */
static void lv_refr_obj(lv_obj_t * obj, const lv_area_t * mask_ori_p)
{
    /*Do not refresh hidden objects*/
    if(obj->hidden != 0) return;

    bool union_ok; /* Store the return value of area_union */
    /* Truncate the original mask to the coordinates of the parent
     * because the parent and its children are visible only here */
    lv_area_t obj_mask;
    lv_area_t obj_ext_mask;
    lv_area_t obj_area;
    lv_coord_t ext_size = obj->ext_draw_pad;
    lv_obj_get_coords(obj, &obj_area);
    obj_area.x1 -= ext_size;
    obj_area.y1 -= ext_size;
    obj_area.x2 += ext_size;
    obj_area.y2 += ext_size;
    union_ok = _lv_area_intersect(&obj_ext_mask, mask_ori_p, &obj_area);

    /*Draw the parent and its children only if they ore on 'mask_parent'*/
    if(union_ok != false) {

        /* Redraw the object */
        if(obj->design_cb) obj->design_cb(obj, &obj_ext_mask, LV_DESIGN_DRAW_MAIN);

#if MASK_AREA_DEBUG
        static lv_color_t debug_color = LV_COLOR_RED;
        lv_draw_rect_dsc_t draw_dsc;
        lv_draw_rect_dsc_init(&draw_dsc);
        draw_dsc.bg_color.full = debug_color.full;
        draw_dsc.bg_opa = LV_OPA_20;
        draw_dsc.border_width = 2;
        draw_dsc.border_opa = LV_OPA_50;
        draw_dsc.border_color.full = (debug_color.full + 0x13) * 9;

        lv_draw_rect(&obj_ext_mask, &obj_ext_mask, &draw_dsc);
        debug_color.full *= 17;
        debug_color.full += 0xA1;
#if LV_COLOR_DEPTH == 32
        debug_color.ch.alpha = 0xff;
#endif
#endif
        /*Create a new 'obj_mask' without 'ext_size' because the children can't be visible there*/
        lv_obj_get_coords(obj, &obj_area);
        union_ok = _lv_area_intersect(&obj_mask, mask_ori_p, &obj_area);
        if(union_ok != false) {
            lv_area_t mask_child; /*Mask from obj and its child*/
            lv_obj_t * child_p;
            lv_area_t child_area;
            _LV_LL_READ_BACK(obj->child_ll, child_p) {
                lv_obj_get_coords(child_p, &child_area);
                ext_size = child_p->ext_draw_pad;
                child_area.x1 -= ext_size;
                child_area.y1 -= ext_size;
                child_area.x2 += ext_size;
                child_area.y2 += ext_size;
                /* Get the union (common parts) of original mask (from obj)
                 * and its child */
                union_ok = _lv_area_intersect(&mask_child, &obj_mask, &child_area);

                /*If the parent and the child has common area then refresh the child */
                if(union_ok) {
                    /*Refresh the next children*/
                    lv_refr_obj(child_p, &mask_child);
                }
            }
        }

        /* If all the children are redrawn make 'post draw' design */
        if(obj->design_cb) obj->design_cb(obj, &obj_ext_mask, LV_DESIGN_DRAW_POST);
    }
}

/**
 * Flush the content of the VDB
 */
static void lv_refr_vdb_flush(void)
{
    lv_disp_buf_t * vdb = lv_disp_get_buf(disp_refr);

    /*In double buffered mode wait until the other buffer is flushed before flushing the current
     * one*/
    if(lv_disp_is_double_buf(disp_refr)) {
        while(vdb->flushing) {
            if(disp_refr->driver.wait_cb) disp_refr->driver.wait_cb(&disp_refr->driver);
        }
    }

    vdb->flushing = 1;

    if(disp_refr->driver.buffer->last_area && disp_refr->driver.buffer->last_part) vdb->flushing_last = 1;
    else vdb->flushing_last = 0;

    /*Flush the rendered content to the display*/
    lv_disp_t * disp = _lv_refr_get_disp_refreshing();
    if(disp->driver.flush_cb) disp->driver.flush_cb(&disp->driver, &vdb->area, vdb->buf_act);

    if(vdb->buf1 && vdb->buf2) {
        if(vdb->buf_act == vdb->buf1)
            vdb->buf_act = vdb->buf2;
        else
            vdb->buf_act = vdb->buf1;
    }
}
