mirror of
https://gitlab.com/sortix/sortix.git
synced 2023-02-13 20:55:38 -05:00
104 lines
3.6 KiB
C++
104 lines
3.6 KiB
C++
/*******************************************************************************
|
|
|
|
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
|
|
|
|
This file is part of the Sortix C Library.
|
|
|
|
The Sortix C 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 3 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The Sortix C 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 the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
stdlib/malloc.cpp
|
|
Allocates a chunk of memory from the dynamic memory heap.
|
|
|
|
*******************************************************************************/
|
|
|
|
#include <errno.h>
|
|
#include <malloc.h>
|
|
#include <stddef.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#if __is_sortix_kernel
|
|
#include <sortix/kernel/kernel.h>
|
|
#endif
|
|
|
|
#if defined(HEAP_NO_ASSERT)
|
|
#define __heap_verify() ((void) 0)
|
|
#undef assert
|
|
#define assert(x) do { ((void) 0); } while ( 0 )
|
|
#endif
|
|
|
|
extern "C" void* malloc(size_t original_size)
|
|
{
|
|
if ( !heap_size_has_bin(original_size) )
|
|
return errno = ENOMEM, (void*) NULL;
|
|
|
|
// Decide how big an allocation we would like to make.
|
|
size_t chunk_outer_size = sizeof(struct heap_chunk) +
|
|
sizeof(struct heap_chunk_post);
|
|
size_t chunk_inner_size = heap_align(original_size);
|
|
size_t chunk_size = chunk_outer_size + chunk_inner_size;
|
|
|
|
if ( !heap_size_has_bin(chunk_size) )
|
|
return errno = ENOMEM, (void*) NULL;
|
|
|
|
// Decide which bins are large enough for our allocation.
|
|
size_t smallest_desirable_bin = heap_bin_for_allocation(chunk_size);
|
|
size_t smallest_desirable_bin_size = heap_size_of_bin(smallest_desirable_bin);
|
|
size_t desirable_bins = ~0UL << smallest_desirable_bin;
|
|
|
|
__heap_lock();
|
|
__heap_verify();
|
|
|
|
// Determine whether there are any bins that we can use.
|
|
size_t usable_bins = desirable_bins & __heap_state.bin_filled_bitmap;
|
|
|
|
// If there are no usable bins, attempt to expand the current part of the
|
|
// heap or create a new part.
|
|
if ( !usable_bins && __heap_expand_current_part(smallest_desirable_bin_size) )
|
|
usable_bins = desirable_bins & __heap_state.bin_filled_bitmap;
|
|
|
|
// If we failed to expand the current part or make a new one - then we are
|
|
// officially out of memory until someone deallocates something.
|
|
if ( !usable_bins )
|
|
{
|
|
__heap_verify();
|
|
__heap_unlock();
|
|
return (void*) NULL;
|
|
}
|
|
|
|
// Pick the smallest of the usable bins.
|
|
size_t bin_index = heap_bsf(usable_bins);
|
|
|
|
// Pick the first element of this bins linked list. This is our allocation.
|
|
struct heap_chunk* result_chunk = __heap_state.bin[bin_index];
|
|
assert(result_chunk);
|
|
assert(HEAP_IS_POINTER_ALIGNED(result_chunk, result_chunk->chunk_size));
|
|
|
|
assert(chunk_size <= result_chunk->chunk_size);
|
|
|
|
// Mark our chosen chunk as used and remove it from its bin.
|
|
heap_remove_chunk(result_chunk);
|
|
|
|
// If our chunk is larger than what we really needed and it is possible to
|
|
// split the chunk into two, then we should split off a part of it and
|
|
// return it to the heap for further allocation.
|
|
if ( heap_can_split_chunk(result_chunk, chunk_size) )
|
|
heap_split_chunk(result_chunk, chunk_size);
|
|
|
|
__heap_verify();
|
|
__heap_unlock();
|
|
|
|
// Return the inner data associated with the chunk to the caller.
|
|
return heap_chunk_to_data(result_chunk);
|
|
}
|