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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 #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 
34 struct memory_block {
35 	struct memory_block * next;
36 };
37 
memory_pool_init(struct memory_pool * pool)38 void memory_pool_init(struct memory_pool * pool)
39 {
40 	memset(pool, 0, sizeof(struct memory_pool));
41 }
42 
43 
memory_pool_destroy(struct memory_pool * pool)44 void 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 
refill_pool(struct memory_pool * pool)53 static 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 = 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 
memory_pool_malloc(struct memory_pool * pool,unsigned int bytes)71 void * 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 = 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