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 */
46struct 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
58int
59nouveau_heap_init(struct nouveau_heap **heap, unsigned start,
60                  unsigned size);
61
62void
63nouveau_heap_destroy(struct nouveau_heap **heap);
64
65int
66nouveau_heap_alloc(struct nouveau_heap *heap, unsigned size, void *priv,
67                   struct nouveau_heap **);
68
69void
70nouveau_heap_free(struct nouveau_heap **);
71
72#endif
73