obj_pool.h

   1 #ifndef OBJ_POOL_H_
   2 #define OBJ_POOL_H_
   3
   4 #include <stdint.h>
   5 #include <stdlib.h>
   6
   7 #define obj_pool_gen(pre, obj_t, initial_capacity)                         \
   8 static struct {                                                            \
   9     uint32_t size;                                                         \
  10     uint32_t capacity;                                                     \
  11     obj_t *base;                                                           \
  12 } pre##_pool = { 0, 0, NULL};                                              \
  13 static uint32_t pre##_alloc(uint32_t count)                                \
  14 {                                                                          \
  15     uint32_t offset;                                                       \
  16     while (pre##_pool.size + count > pre##_pool.capacity) {                \
  17         if (pre##_pool.capacity) {                                         \
  18             pre##_pool.capacity *= 2;                                      \
  19         } else {                                                           \
  20             pre##_pool.capacity = initial_capacity;                        \
  21         }                                                                  \
  22         pre##_pool.base =                                                  \
  23             realloc(pre##_pool.base, pre##_pool.capacity * sizeof(obj_t)); \
  24     }                                                                      \
  25     offset = pre##_pool.size;                                              \
  26     pre##_pool.size += count;                                              \
  27     return offset;                                                         \
  28 }                                                                          \
  29 static void pre##_free(uint32_t count)                                     \
  30 {                                                                          \
  31     pre##_pool.size -= count;                                              \
  32 }                                                                          \
  33 static uint32_t pre##_offset(obj_t * obj)                                  \
  34 {                                                                          \
  35     return obj == NULL ? ~0 : obj - pre##_pool.base;                       \
  36 }                                                                          \
  37 static obj_t *pre##_pointer(uint32_t offset)                               \
  38 {                                                                          \
  39     return offset >= pre##_pool.size ? NULL : &pre##_pool.base[offset];    \
  40 }                                                                          \
  41
  42 #endif