src/gallium/drivers/nouveau/nouveau_heap.h

   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