modules/codec/vlc_fifo_helper.h

   1 /*****************************************************************************
   2  * vlc_fifo_helper.h: Basic FIFO helper functions
   3  *****************************************************************************
   4  * Copyright (C) 2017 VLC authors and VideoLAN
   5  *
   6  * Authors: Steve Lhomme <robux4@gmail.com>
   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 VLC_FIFO_HELPER_H
  24 #define VLC_FIFO_HELPER_H 1
  25
  26 typedef struct FIFO_ITEM {
  27     struct FIFO_ITEM  *p_next;
  28 } fifo_item_t;
  29
  30 typedef struct
  31 {
  32     fifo_item_t  *p_first;
  33     fifo_item_t  **pp_last;
  34     size_t     i_depth;
  35 } fifo_t;
  36
  37 static inline void fifo_Init(fifo_t *p_fifo)
  38 {
  39     p_fifo->p_first = NULL;
  40     p_fifo->pp_last = &p_fifo->p_first;
  41     p_fifo->i_depth = 0;
  42 }
  43
  44 static inline void fifo_Release(fifo_t *fifo)
  45 {
  46     assert(fifo->i_depth == 0); /* we should have poped all the items */
  47 }
  48
  49 static inline size_t fifo_GetCount(fifo_t *fifo)
  50 {
  51     return fifo->i_depth;
  52 }
  53
  54 static inline fifo_item_t *fifo_Show(fifo_t *p_fifo)
  55 {
  56     fifo_item_t *b;
  57
  58     assert(p_fifo->p_first != NULL);
  59     b = p_fifo->p_first;
  60
  61     return b;
  62 }
  63
  64 static inline fifo_item_t *fifo_Get(fifo_t *fifo)
  65 {
  66     fifo_item_t *block = fifo->p_first;
  67
  68     if (block == NULL)
  69         return NULL; /* Nothing to do */
  70
  71     fifo->p_first = block->p_next;
  72     if (block->p_next == NULL)
  73         fifo->pp_last = &fifo->p_first;
  74     block->p_next = NULL;
  75
  76     assert(fifo->i_depth > 0);
  77     fifo->i_depth--;
  78
  79     return block;
  80 }
  81
  82 static inline void fifo_Put(fifo_t *fifo, fifo_item_t *p_item)
  83 {
  84     *(fifo->pp_last) = p_item;
  85
  86     while (p_item != NULL)
  87     {
  88         fifo->pp_last = &p_item->p_next;
  89         fifo->i_depth++;
  90
  91         p_item = p_item->p_next;
  92     }
  93 }
  94
  95 /* macro to get the proper item type in/out of the FIFO
  96  * The item type must have a field fifo_item_t named fifo
  97  */
  98 #define TYPED_FIFO(type, prefix)                                      \
  99 static inline void prefix ## _fifo_Init(fifo_t *p_fifo)               \
 100 {                                                                     \
 101     fifo_Init(p_fifo);                                                \
 102 }                                                                     \
 103 static inline void prefix ## _fifo_Release(fifo_t *p_fifo)            \
 104 {                                                                     \
 105     fifo_Release(p_fifo);                                             \
 106 }                                                                     \
 107 static inline void prefix ## _fifo_Put(fifo_t *p_fifo, type *p_item)  \
 108 {                                                                     \
 109     fifo_Put(p_fifo, &p_item->fifo);                                  \
 110 }                                                                     \
 111 static inline type *prefix ## _fifo_Get(fifo_t *p_fifo)               \
 112 {                                                                     \
 113     return (type*)fifo_Get(p_fifo);                                   \
 114 }                                                                     \
 115 static inline type *prefix ## _fifo_Show(fifo_t *p_fifo)              \
 116 {                                                                     \
 117     return (type*)fifo_Show(p_fifo);                                  \
 118 }                                                                     \
 119 static inline size_t prefix ## _fifo_GetCount(fifo_t *fifo)           \
 120 {                                                                     \
 121     return fifo->i_depth;                                             \
 122 }
 123
 124
 125 #endif /* VLC_FIFO_HELPER_H */