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#include "memory_pool.h"
24
25#include <assert.h>
26#include <stdlib.h>
27#include <string.h>
28
29
30#define POOL_LARGE_ALLOC 4096
31#define POOL_ALIGN 8
32
33
34struct memory_block {
35	struct memory_block * next;
36};
37
38void memory_pool_init(struct memory_pool * pool)
39{
40	memset(pool, 0, sizeof(struct memory_pool));
41}
42
43
44void memory_pool_destroy(struct memory_pool * pool)
45{
46	while(pool->blocks) {
47		struct memory_block * block = pool->blocks;
48		pool->blocks = block->next;
49		free(block);
50	}
51}
52
53static void refill_pool(struct memory_pool * pool)
54{
55	unsigned int blocksize = pool->total_allocated;
56	struct memory_block * newblock;
57
58	if (!blocksize)
59		blocksize = 2*POOL_LARGE_ALLOC;
60
61	newblock = (struct memory_block*)malloc(blocksize);
62	newblock->next = pool->blocks;
63	pool->blocks = newblock;
64
65	pool->head = (unsigned char*)(newblock + 1);
66	pool->end = ((unsigned char*)newblock) + blocksize;
67	pool->total_allocated += blocksize;
68}
69
70
71void * memory_pool_malloc(struct memory_pool * pool, unsigned int bytes)
72{
73	if (bytes < POOL_LARGE_ALLOC) {
74		void * ptr;
75
76		if (pool->head + bytes > pool->end)
77			refill_pool(pool);
78
79		assert(pool->head + bytes <= pool->end);
80
81		ptr = pool->head;
82
83		pool->head += bytes;
84		pool->head = (unsigned char*)(((unsigned long)pool->head + POOL_ALIGN - 1) & ~(POOL_ALIGN - 1));
85
86		return ptr;
87	} else {
88		struct memory_block * block = (struct memory_block*)malloc(bytes + sizeof(struct memory_block));
89
90		block->next = pool->blocks;
91		pool->blocks = block;
92
93		return (block + 1);
94	}
95}
96
97
98