modules/visualization/cyclic_buffer.h

   1 /*****************************************************************************
   2  * cyclic_buffer.h cyclic buffer helper class for vlc's audio visualizations
   3  *****************************************************************************
   4  * Copyright © 2012 Vovoid Media Technologies
   5  *
   6  * Authors: Jonatan "jaw" Wallmander
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifndef CYCLIC_BUFFER_H
  24 #define CYCLIC_BUFFER_H
  25
  26
  27 class block_holder
  28 {
  29 public:
  30     float data[512]; // data holder
  31     vlc_tick_t pts; // machine time when this is to be played
  32     block_holder()
  33     {
  34         pts = 0; // max_int 64-bit
  35     }
  36 };
  37
  38 #define CYCLIC_BUFFER_SIZE 128
  39 class cyclic_block_queue
  40 {
  41     block_holder cycl_buffer[CYCLIC_BUFFER_SIZE];
  42     size_t consumer_pos;
  43     size_t insertion_pos;
  44 public:
  45     cyclic_block_queue()
  46     {
  47         consumer_pos = 0;
  48         insertion_pos = 0;
  49     }
  50
  51     block_holder* consume()
  52     {
  53         vlc_tick_t cur_machine_time = vlc_tick_now();
  54         size_t steps = 0;
  55         while (
  56                (cycl_buffer[consumer_pos].pts < cur_machine_time)
  57                &&
  58                (steps++ < CYCLIC_BUFFER_SIZE)
  59               )
  60         {
  61             consumer_pos++;
  62             if (consumer_pos == CYCLIC_BUFFER_SIZE)
  63             {
  64                 consumer_pos = 0;
  65             }
  66         }
  67         return &cycl_buffer[consumer_pos];
  68     }
  69
  70   block_holder* get_insertion_object()
  71   {
  72       insertion_pos++;
  73       if ( insertion_pos == CYCLIC_BUFFER_SIZE )
  74       {
  75           insertion_pos = 0;
  76       }
  77       return &cycl_buffer[insertion_pos];
  78   }
  79
  80   void reset()
  81   {
  82       for (size_t i = 0; i < CYCLIC_BUFFER_SIZE; i++)
  83       {
  84           cycl_buffer[i].pts = 0;
  85           consumer_pos = 0;
  86           insertion_pos = 0;
  87       }
  88   }
  89 };
  90 #undef CYCLIC_BUFFER_SIZE
  91
  92 #endif // CYCLIC_BUFFER_H