--- /dev/null
+/* EINA - EFL data type library
+ * Copyright (C) 2009 Jorge Luis Zapata Muga
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library;
+ * if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * This is a naive 'buddy' allocator following Knuth's documentation.
+ * The main difference is that we dont store the block information
+ * on the block memory itself but on another malloc'd area.
+ * This is useful for managing memory which isnt as fast as the main
+ * memory like the video memory
+ * The algorithm uses an area to store the linked list of blocks.
+ * Each block size is equal to the minimum allocatable block size for
+ * the memory pool and the number of blocks is equal to the size of the
+ * memory pool divided by the block size.
+ */
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdio.h>
+
+#include "eina_types.h"
+#include "eina_inlist.h"
+#include "eina_module.h"
+#include "eina_mempool.h"
+#include "eina_private.h"
+
+typedef struct _Block
+{
+ EINA_INLIST;
+ Eina_Bool available : 1;
+ unsigned short int order : 7; /* final order is order + min_order */
+} Block;
+
+typedef struct _Buddy
+{
+ void *heap; /* start address of the heap */
+ size_t size; /* total size in bytes of the heap */
+ unsigned int min_order; /* minimum size is 1 << min_order */
+ unsigned int max_order; /* maximum size is 1 << max_order */
+ unsigned int num_order; /* number of orders */
+ Eina_Inlist **areas; /* one area per order */
+ Block *blocks; /* the allocated block information */
+} Buddy;
+
+/* get the minimum order greater or equal to size */
+static inline unsigned int _get_order(Buddy *b, size_t size)
+{
+ unsigned int i;
+ size_t bytes;
+
+ bytes = 1 << b->min_order;
+ for (i = 0; bytes < size && i < b->num_order; i++)
+ {
+ bytes += bytes;
+ }
+ //printf("order for size %d is %d\n", size, i + b->min_order);
+ return i;
+}
+
+static inline void * _get_offset(Buddy *b, Block *block)
+{
+ void *ret;
+
+ ret = (char *)b->heap + ((block - &b->blocks[0]) << b->min_order);
+ return ret;
+}
+
+static void *_init(__UNUSED__ const char *context, __UNUSED__ const char *options, va_list args)
+{
+ Buddy *b;
+ int i;
+ size_t bytes;
+ size_t size;
+ size_t min_order;
+ void *heap;
+
+ heap = va_arg(args, void *);
+ size = va_arg(args, size_t);
+ min_order = va_arg(args, int);
+ /* the minimum order we support is 15 (32K) */
+ min_order = min_order < 15 ? 15 : min_order;
+ bytes = 1 << min_order;
+ for (i = 0; bytes <= size; i++)
+ {
+ bytes += bytes;
+ }
+ if (!i)
+ {
+ return NULL;
+ }
+ b = malloc(sizeof(Buddy));
+ b->heap = heap;
+ b->size = size;
+ b->min_order = min_order;
+ b->max_order = min_order + i - 1;
+ b->num_order = i;
+ b->areas = calloc(b->num_order, sizeof(Eina_Inlist *));
+ b->blocks = calloc(1 << (b->num_order - 1), sizeof(Block));
+ /* setup the initial free area */
+ b->blocks[0].available = EINA_TRUE;
+ b->areas[b->num_order - 1] = EINA_INLIST_GET(&(b->blocks[0]));
+
+ return b;
+}
+
+static void _shutdown(void *data)
+{
+ Buddy *b = data;
+
+ free(b->blocks);
+ free(b->areas);
+ free(b);
+}
+
+static void _free(void *data, void *element)
+{
+ Buddy *b = data;
+ Block *block, *buddy;
+ unsigned int offset;
+ unsigned int index;
+
+ offset = element - b->heap;
+ if (offset > b->size)
+ return;
+ index = offset >> b->min_order;
+ block = &b->blocks[index];
+
+ //printf("free %x index = %d order = %d buddy = %d\n", offset, index, block->order, index ^ (1 << block->order));
+ /* we should always work with the buddy at right */
+ if (index & (1 << block->order))
+ {
+ Block *left;
+
+ index = index ^ (1 << block->order);
+ left = &b->blocks[index];
+ if (!left->available)
+ goto end;
+ else
+ {
+ buddy = block;
+ block = left;
+ b->areas[block->order] = eina_inlist_remove(b->areas[block->order], EINA_INLIST_GET(block));
+ block->order++;
+ }
+ }
+check:
+ /* already on the last order */
+ if (block->order + b->min_order == b->max_order)
+ goto end;
+ /* get the buddy */
+ buddy = &b->blocks[index ^ (1 << block->order)];
+ if (!buddy->available)
+ goto end;
+ /* merge two blocks */
+ b->areas[block->order] = eina_inlist_remove(b->areas[block->order], EINA_INLIST_GET(buddy));
+ block->order++;
+ goto check;
+end:
+ /* add the block to the free list */
+ block->available = EINA_TRUE;
+ b->areas[block->order] = eina_inlist_append(b->areas[block->order], EINA_INLIST_GET(block));
+}
+
+static void *_alloc(void *data, unsigned int size)
+{
+ Buddy *b = data;
+ Block *block, *buddy;
+ unsigned int k, j;
+
+ k = j = _get_order(b, size);
+ /* get a free list of order k where k <= j <= max_order */
+ while ((j < b->num_order) && !b->areas[j])
+ j++;
+ /* check that the order is on our range */
+ if (j + b->min_order > b->max_order)
+ return NULL;
+
+ /* get a free element on this order, if not, go splitting until we find one */
+ //printf("getting order %d (%d) for size %d\n", j, k, size);
+found:
+ if (j == k)
+ {
+ void *ret;
+
+ block = EINA_INLIST_CONTAINER_GET(b->areas[j], Block);
+ block->available = EINA_FALSE;
+ block->order = j;
+ /* remove the block from the list */
+ b->areas[j] = eina_inlist_remove(b->areas[j], EINA_INLIST_GET(block));
+ ret = _get_offset(b, block);
+
+ return ret;
+ }
+ block = EINA_INLIST_CONTAINER_GET(b->areas[j], Block);
+ /* split */
+ b->areas[j] = eina_inlist_remove(b->areas[j], EINA_INLIST_GET(block));
+ j--;
+ b->areas[j] = eina_inlist_append(b->areas[j], EINA_INLIST_GET(block));
+ buddy = block + (1 << j);
+ buddy->order = j;
+ buddy->available = EINA_TRUE;
+ b->areas[j] = eina_inlist_append(b->areas[j], EINA_INLIST_GET(buddy));
+
+ goto found;
+}
+
+static void _statistics(void *data)
+{
+ Buddy *b = data;
+ unsigned int i;
+
+ printf("Information:\n");
+ printf("size = %d, min_order = %d, max_order = %d, num_order = %d, num_blocks = %d (%dKB)\n", b->size, b->min_order, b->max_order, b->num_order, 1 << b->num_order, ((1 << (b->num_order)) * sizeof(Block)) / 1024);
+ printf("Area dumping:");
+ /* iterate over the free lists and dump the maps */
+ for (i = 0; i < b->num_order; i++)
+ {
+ Block *block;
+
+ printf("\n2^%d:", b->min_order + i);
+ EINA_INLIST_FOREACH(b->areas[i], block)
+ {
+ printf(" %d", (block - &b->blocks[0]));
+ }
+ }
+ printf("\nBlocks dumping:\n");
+}
+
+static Eina_Mempool_Backend _backend = {
+ "buddy",
+ &_init,
+ &_free,
+ &_alloc,
+ NULL, /* realloc */
+ NULL, /* garbage collect */
+ &_statistics,
+ &_shutdown
+};
+
+Eina_Bool buddy_init(void)
+{
+ return eina_mempool_register(&_backend);
+}
+
+void buddy_shutdown(void)
+{
+ eina_mempool_unregister(&_backend);
+}
+
+
+#ifndef EINA_STATIC_BUILD_BUDDY
+
+EINA_MODULE_INIT(buddy_init);
+EINA_MODULE_SHUTDOWN(buddy_shutdown);
+
+#endif /* ! EINA_STATIC_BUILD_BUDDY */
projects / framework / uifw / eina.git / commitdiff