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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.