src/commonlib/mem_pool.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <commonlib/helpers.h>
   4 #include <commonlib/mem_pool.h>
   5
   6 void *mem_pool_alloc(struct mem_pool *mp, size_t sz)
   7 {
   8         void *p;
   9
  10         if (mp->alignment == 0)
  11                 return NULL;
  12
  13         /* We assume that mp->buf started mp->alignment aligned */
  14         sz = ALIGN_UP(sz, mp->alignment);
  15
  16         /* Determine if any space available. */
  17         if ((mp->size - mp->free_offset) < sz)
  18                 return NULL;
  19
  20         p = &mp->buf[mp->free_offset];
  21
  22         mp->free_offset += sz;
  23         mp->second_to_last_alloc = mp->last_alloc;
  24         mp->last_alloc = p;
  25
  26         return p;
  27 }
  28
  29 void mem_pool_free(struct mem_pool *mp, void *p)
  30 {
  31         /* Determine if p was the most recent allocation. */
  32         if (p == NULL || mp->last_alloc != p)
  33                 return;
  34
  35         mp->free_offset = mp->last_alloc - mp->buf;
  36         mp->last_alloc = mp->second_to_last_alloc;
  37         /* No way to track allocation before this one. */
  38         mp->second_to_last_alloc = NULL;
  39 }