include/circbuf.h

   1 /*
   2  * Copyright (c) 2012 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to deal
   6  * in the Software without restriction, including without limitation the rights
   7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8  * copies of the Software, and to permit persons to whom the Software is
   9  * furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  20  * SOFTWARE.
  21  */
  22
  23 #ifndef __CIRCBUF_H
  24 #define __CIRCBUF_H
  25
  26 struct circbuf {
  27         u32 start;                      /* the oldest entry idx */
  28         u32 filled;                     /* the number of entries */
  29         u32 size;                       /* the size of each entry */
  30         u32 count;                      /* the max number of entries */
  31         u8 data[0];
  32 };
  33
  34 #define CIRCBUF(name, n, s)     struct circbuf name; u8 __circbuf_##name[(n)*sizeof(s)]
  35
  36 #define init_circbuf(c, t, n)   __init_circbuf((c), sizeof(t), (n))
  37 static inline void __init_circbuf(struct circbuf *c, u32 size, u32 count)
  38 {
  39         c->start = 0;
  40         c->filled = 0;
  41         c->size = size;
  42         c->count = count;
  43 }
  44
  45 static inline void insert_circbuf(struct circbuf *c, void *data)
  46 {
  47         u32 idx;
  48
  49         if (c->filled == c->count) {
  50                 idx = c->start;
  51                 c->start = (c->start+1) % c->count;
  52         } else {
  53                 idx = (c->start + c->filled) % c->count;
  54                 c->filled++;
  55         }
  56
  57         memcpy(c->data + (idx * c->size), data, c->size);
  58 }
  59
  60 static inline int remove_circbuf(struct circbuf *c, void *data)
  61 {
  62         if (!c->filled)
  63                 return 0;
  64
  65         memcpy(data, c->data + (c->start * c->size), c->size);
  66
  67         c->start = (c->start+1) % c->count;
  68         c->filled--;
  69         return 1;
  70 }
  71
  72 static inline int pending_circbuf(struct circbuf *c)
  73 {
  74         return c->filled != 0;
  75 }
  76
  77 #endif