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/*
* Copyright (c) 2010, Andrea Mazzoleni. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "tommyalloc.h"
/******************************************************************************/
/* allocator */
/**
* Basic allocation segment.
* Smaller of a memory page, to allow also a little heap overread.
* The heap manager may put it in a single memory page.
*/
#define TOMMY_ALLOCATOR_BLOCK_SIZE (4096 - 64)
void tommy_allocator_init(tommy_allocator* alloc, tommy_size_t block_size, tommy_size_t align_size)
{
/* setup the minimal alignment */
if (align_size < sizeof(void*))
align_size = sizeof(void*);
/* ensure that the block_size keeps the alignment */
if (block_size % align_size != 0)
block_size += align_size - block_size % align_size;
alloc->block_size = block_size;
alloc->align_size = align_size;
alloc->count = 0;
alloc->free_block = 0;
alloc->used_segment = 0;
}
/**
* Reset the allocator and free all.
*/
static void allocator_reset(tommy_allocator* alloc)
{
tommy_allocator_entry* block = alloc->used_segment;
while (block) {
tommy_allocator_entry* block_next = block->next;
tommy_free(block);
block = block_next;
}
alloc->count = 0;
alloc->free_block = 0;
alloc->used_segment = 0;
}
void tommy_allocator_done(tommy_allocator* alloc)
{
allocator_reset(alloc);
}
void* tommy_allocator_alloc(tommy_allocator* alloc)
{
void* ptr;
/* if no free block available */
if (!alloc->free_block) {
tommy_uintptr_t off, mis;
tommy_size_t size;
char* data;
tommy_allocator_entry* segment;
/* default allocation size */
size = TOMMY_ALLOCATOR_BLOCK_SIZE;
/* ensure that we can allocate at least one block */
if (size < sizeof(tommy_allocator_entry) + alloc->align_size + alloc->block_size)
size = sizeof(tommy_allocator_entry) + alloc->align_size + alloc->block_size;
data = tommy_cast(char*, tommy_malloc(size));
segment = (tommy_allocator_entry*)data;
/* put in the segment list */
segment->next = alloc->used_segment;
alloc->used_segment = segment;
data += sizeof(tommy_allocator_entry);
/* align if not aligned */
off = (tommy_uintptr_t)data;
mis = off % alloc->align_size;
if (mis != 0) {
data += alloc->align_size - mis;
size -= alloc->align_size - mis;
}
/* insert in free list */
do {
tommy_allocator_entry* free_block = (tommy_allocator_entry*)data;
free_block->next = alloc->free_block;
alloc->free_block = free_block;
data += alloc->block_size;
size -= alloc->block_size;
} while (size >= alloc->block_size);
}
/* remove one from the free list */
ptr = alloc->free_block;
alloc->free_block = alloc->free_block->next;
++alloc->count;
return ptr;
}
void tommy_allocator_free(tommy_allocator* alloc, void* ptr)
{
tommy_allocator_entry* free_block = tommy_cast(tommy_allocator_entry*, ptr);
/* put it in the free list */
free_block->next = alloc->free_block;
alloc->free_block = free_block;
--alloc->count;
}
tommy_size_t tommy_allocator_memory_usage(tommy_allocator* alloc)
{
return alloc->count * (tommy_size_t)alloc->block_size;
}
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