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Diffstat (limited to 'third-party/tommyds/tommyalloc.c')
-rw-r--r-- | third-party/tommyds/tommyalloc.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/third-party/tommyds/tommyalloc.c b/third-party/tommyds/tommyalloc.c new file mode 100644 index 0000000..0da604c --- /dev/null +++ b/third-party/tommyds/tommyalloc.c @@ -0,0 +1,150 @@ +/* + * 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; +} + |