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1 /*
2  * Copyright 2007 Nouveau Project
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  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  */
22 
23 #ifndef __NOUVEAU_HEAP_H__
24 #define __NOUVEAU_HEAP_H__
25 
26 /* This datastructure represents a memory allocation heap. Fundamentally, this
27  * is a doubly-linked list with a few properties, and a usage convention.
28  *
29  * On initial allocation, there is a single node with the full size that's
30  * marked as not in-use. As allocations are made, blocks are taken off the end
31  * of that first node, and inserted right after it. If the first node doesn't
32  * have enough free space, we look for free space down in the rest of the
33  * list. This can happen if an allocation is made and then freed.
34  *
35  * The first node will remain with in_use == 0 even if the whole heap is
36  * exhausted. Another invariant is that there will never be two sequential
37  * in_use == 0 nodes. If a node is freed and it has one (or both) adjacent
38  * free nodes, they are merged into one, and the relevant heap entries are
39  * freed.
40  *
41  * The pattern to free the whole heap is to start with the first node and then
42  * just free the "next" node, until there is no next node. This should assure
43  * that at the end the first (and only) node is not in use and contains the
44  * full size of the heap.
45  */
46 struct nouveau_heap {
47    struct nouveau_heap *prev;
48    struct nouveau_heap *next;
49 
50    void *priv;
51 
52    unsigned start;
53    unsigned size;
54 
55    int in_use;
56 };
57 
58 int
59 nouveau_heap_init(struct nouveau_heap **heap, unsigned start,
60                   unsigned size);
61 
62 void
63 nouveau_heap_destroy(struct nouveau_heap **heap);
64 
65 int
66 nouveau_heap_alloc(struct nouveau_heap *heap, unsigned size, void *priv,
67                    struct nouveau_heap **);
68 
69 void
70 nouveau_heap_free(struct nouveau_heap **);
71 
72 #endif
73