gistfile1.rb

 # all indexes are 0-based                                                   
  2 def page_map(page, count, vidaas_count = 20)                                
  3                                                                             
  4   start_idx = page * count                                                  
  5                                                                             
  6   first_page = start_idx / vidaas_count                                     
  7   last_page = first_page + (count / vidaas_count)                           
  8                                                                             
  9   start_offset = start_idx % vidaas_count                                   
 10   end_offset = start_idx + count                                            
 11                                                                             
 12   return {                                                                  
 13     :pages => (first_page...last_page),                                     
 14     :indexes => (start_offset..end_offset)                                  
 15   }                                                                         
 16                                                                             
 17 end