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
26struct 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 */
37struct memory_pool {
38	unsigned char * head;
39	unsigned char * end;
40	unsigned int total_allocated;
41	struct memory_block * blocks;
42};
43
44
45void memory_pool_init(struct memory_pool * pool);
46void memory_pool_destroy(struct memory_pool * pool);
47void * 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