103 lines
3.5 KiB
C++
103 lines
3.5 KiB
C++
/*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version 2
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This program 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 General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*/
|
|
#pragma once
|
|
|
|
/** \file
|
|
* \ingroup bli
|
|
*
|
|
* An `Allocator` can allocate and deallocate memory. It is used by containers such as
|
|
* blender::Vector. The allocators defined in this file do not work with standard library
|
|
* containers such as std::vector.
|
|
*
|
|
* Every allocator has to implement two methods:
|
|
* void *allocate(size_t size, size_t alignment, const char *name);
|
|
* void deallocate(void *ptr);
|
|
*
|
|
* We don't use the std::allocator interface, because it does more than is really necessary for an
|
|
* allocator and has some other quirks. It mixes the concepts of allocation and construction. It is
|
|
* essentially forced to be a template, even though the allocator should not care about the type.
|
|
* Also see http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2271.html#std_allocator. Some
|
|
* of these aspects have been improved in new versions of C++, so we might have to reevaluate the
|
|
* strategy later on.
|
|
*
|
|
* The allocator interface dictated by this file is very simplistic, but for now that is all we
|
|
* need. More complexity can be added when it seems necessary.
|
|
*/
|
|
|
|
#include <algorithm>
|
|
#include <stdlib.h>
|
|
|
|
#include "MEM_guardedalloc.h"
|
|
|
|
#include "BLI_math_base.h"
|
|
#include "BLI_utildefines.h"
|
|
|
|
namespace blender {
|
|
|
|
/**
|
|
* Use Blender's guarded allocator (aka MEM_*). This should always be used except there is a
|
|
* good reason not to use it.
|
|
*/
|
|
class GuardedAllocator {
|
|
public:
|
|
void *allocate(size_t size, size_t alignment, const char *name)
|
|
{
|
|
/* Should we use MEM_mallocN, when alignment is small? If yes, how small must alignment be? */
|
|
return MEM_mallocN_aligned(size, alignment, name);
|
|
}
|
|
|
|
void deallocate(void *ptr)
|
|
{
|
|
MEM_freeN(ptr);
|
|
}
|
|
};
|
|
|
|
/**
|
|
* This is a wrapper around malloc/free. Only use this when the GuardedAllocator cannot be
|
|
* used. This can be the case when the allocated memory might live longer than Blender's
|
|
* allocator. For example, when the memory is owned by a static variable.
|
|
*/
|
|
class RawAllocator {
|
|
private:
|
|
struct MemHead {
|
|
int offset;
|
|
};
|
|
|
|
public:
|
|
void *allocate(size_t size, size_t alignment, const char *UNUSED(name))
|
|
{
|
|
BLI_assert(is_power_of_2_i(static_cast<int>(alignment)));
|
|
void *ptr = malloc(size + alignment + sizeof(MemHead));
|
|
void *used_ptr = reinterpret_cast<void *>(
|
|
reinterpret_cast<uintptr_t>(POINTER_OFFSET(ptr, alignment + sizeof(MemHead))) &
|
|
~(static_cast<uintptr_t>(alignment) - 1));
|
|
int offset = static_cast<int>((intptr_t)used_ptr - (intptr_t)ptr);
|
|
BLI_assert(offset >= static_cast<int>(sizeof(MemHead)));
|
|
(static_cast<MemHead *>(used_ptr) - 1)->offset = offset;
|
|
return used_ptr;
|
|
}
|
|
|
|
void deallocate(void *ptr)
|
|
{
|
|
MemHead *head = static_cast<MemHead *>(ptr) - 1;
|
|
int offset = -head->offset;
|
|
void *actual_pointer = POINTER_OFFSET(ptr, offset);
|
|
free(actual_pointer);
|
|
}
|
|
};
|
|
|
|
} // namespace blender
|