request_video_bitmap - Triple buffering page flip request. Allegro game programming library.

       This function is used for triple buffering. It requests a page flip to display the specified video bitmap
       object,  but  returns immediately rather than waiting for a retrace. The flip will then take place during
       the next vertical retrace, but you can  carry  on  running  other  code  in  the  meantime  and  use  the
       poll_scroll() routine to detect when the flip has actually taken place. Triple buffering is only possible
       on certain hardware: see the comments about request_scroll(). Example:

          int current_page;
          BITMAP *video_page[3];
          ...
          /* Create pages for page flipping */
          video_page[0] = create_video_bitmap(SCREEN_W, SCREEN_H);
          video_page[1] = create_video_bitmap(SCREEN_W, SCREEN_H);
          video_page[2] = create_video_bitmap(SCREEN_W, SCREEN_H);
          current_page = 0;
          ...
          /* draw the screen and flip pages */
          draw_screen(video_page[current_page]);
          do {
          } while (poll_scroll());
          request_video_bitmap(video_page[current_page]);
          current_page = (current_page+1)%3;
          ...

       request_video_bitmap - Triple buffering page flip request. Allegro game programming library.

       Returns zero on success and non-zero on failure.

poll_scroll(3alleg4),  request_scroll(3alleg4),  gfx_capabilities(3alleg4), create_video_bitmap(3alleg4),
       scroll_screen(3alleg4), ex3buf(3alleg4), exupdate(3alleg4)

Allegro                                           version 4.4.3                    request_video_bitmap(3alleg4)

#include<allegro.h>intrequest_video_bitmap(BITMAP*bitmap);