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