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  1. /*
  2.  * Copyright 2009 Nicolai Hähnle <nhaehnle@gmail.com>
  3.  *
  4.  * Permission is hereby granted, free of charge, to any person obtaining a
  5.  * copy of this software and associated documentation files (the "Software"),
  6.  * to deal in the Software without restriction, including without limitation
  7.  * on the rights to use, copy, modify, merge, publish, distribute, sub
  8.  * license, and/or sell copies of the Software, and to permit persons to whom
  9.  * the Software is furnished to do so, subject to the following conditions:
  10.  *
  11.  * The above copyright notice and this permission notice (including the next
  12.  * paragraph) shall be included in all copies or substantial portions of the
  13.  * Software.
  14.  *
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  18.  * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
  19.  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  20.  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  21.  * USE OR OTHER DEALINGS IN THE SOFTWARE. */
  22.  
  23. #ifndef MEMORY_POOL_H
  24. #define MEMORY_POOL_H
  25.  
  26. struct memory_block;
  27.  
  28. /**
  29.  * Provides a pool of memory that can quickly be allocated from, at the
  30.  * cost of being unable to explicitly free one of the allocated blocks.
  31.  * Instead, the entire pool can be freed at once.
  32.  *
  33.  * The idea is to allow one to quickly allocate a flexible amount of
  34.  * memory during operations like shader compilation while avoiding
  35.  * reference counting headaches.
  36.  */
  37. struct memory_pool {
  38.         unsigned char * head;
  39.         unsigned char * end;
  40.         unsigned int total_allocated;
  41.         struct memory_block * blocks;
  42. };
  43.  
  44.  
  45. void memory_pool_init(struct memory_pool * pool);
  46. void memory_pool_destroy(struct memory_pool * pool);
  47. void * memory_pool_malloc(struct memory_pool * pool, unsigned int bytes);
  48.  
  49.  
  50. /**
  51.  * Generic helper for growing an array that has separate size/count
  52.  * and reserved counters to accomodate up to num new element.
  53.  *
  54.  *  type * Array;
  55.  *  unsigned int Size;
  56.  *  unsigned int Reserved;
  57.  *
  58.  * memory_pool_array_reserve(pool, type, Array, Size, Reserved, k);
  59.  * assert(Size + k < Reserved);
  60.  *
  61.  * \note Size is not changed by this macro.
  62.  *
  63.  * \warning Array, Size, Reserved have to be lvalues and may be evaluated
  64.  * several times.
  65.  */
  66. #define memory_pool_array_reserve(pool, type, array, size, reserved, num) do { \
  67.         unsigned int _num = (num); \
  68.         if ((size) + _num > (reserved)) { \
  69.                 unsigned int newreserve = (reserved) * 2; \
  70.                 type * newarray; \
  71.                 if (newreserve < _num) \
  72.                         newreserve = 4 * _num; /* arbitrary heuristic */ \
  73.                 newarray = memory_pool_malloc((pool), newreserve * sizeof(type)); \
  74.                 memcpy(newarray, (array), (size) * sizeof(type)); \
  75.                 (array) = newarray; \
  76.                 (reserved) = newreserve; \
  77.         } \
  78. } while(0)
  79.  
  80. #endif /* MEMORY_POOL_H */
  81.