You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
101 lines
2.6 KiB
C++
101 lines
2.6 KiB
C++
/*
|
|
* This file is part of OpenTTD.
|
|
* OpenTTD 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, version 2.
|
|
* OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
/** @file dyn_arena_alloc.hpp Dynamic chunk-size arena allocator. */
|
|
|
|
#ifndef DYN_ARENA_ALLOC_HPP
|
|
#define DYN_ARENA_ALLOC_HPP
|
|
|
|
#include <vector>
|
|
|
|
/**
|
|
* Custom arena allocator for uniform-size allocations of a variable size.
|
|
* The allocation and chunk sizes may only be changed when the arena is empty.
|
|
*/
|
|
class DynUniformArenaAllocator {
|
|
std::vector<void *> used_blocks;
|
|
|
|
void *current_block = nullptr;
|
|
void *last_freed = nullptr;
|
|
size_t next_position = 0;
|
|
|
|
size_t item_size = 0;
|
|
size_t items_per_chunk = 0;
|
|
|
|
void NewBlock()
|
|
{
|
|
current_block = malloc(item_size * items_per_chunk);
|
|
assert(current_block != nullptr);
|
|
next_position = 0;
|
|
used_blocks.push_back(current_block);
|
|
}
|
|
|
|
public:
|
|
DynUniformArenaAllocator() = default;
|
|
DynUniformArenaAllocator(const DynUniformArenaAllocator &other) = delete;
|
|
DynUniformArenaAllocator& operator=(const DynUniformArenaAllocator &other) = delete;
|
|
|
|
~DynUniformArenaAllocator()
|
|
{
|
|
EmptyArena();
|
|
}
|
|
|
|
void EmptyArena()
|
|
{
|
|
current_block = nullptr;
|
|
last_freed = nullptr;
|
|
next_position = 0;
|
|
for (void *block : used_blocks) {
|
|
free(block);
|
|
}
|
|
used_blocks.clear();
|
|
}
|
|
|
|
void ResetArena()
|
|
{
|
|
EmptyArena();
|
|
item_size = 0;
|
|
items_per_chunk = 0;
|
|
}
|
|
|
|
void *Allocate() {
|
|
assert(item_size != 0);
|
|
if (last_freed) {
|
|
void *ptr = last_freed;
|
|
last_freed = *reinterpret_cast<void**>(ptr);
|
|
return ptr;
|
|
} else {
|
|
if (current_block == nullptr || next_position == items_per_chunk) {
|
|
NewBlock();
|
|
}
|
|
void *out = reinterpret_cast<char *>(current_block) + (item_size * next_position);
|
|
next_position++;
|
|
return out;
|
|
}
|
|
}
|
|
|
|
void Free(void *ptr) {
|
|
if (!ptr) return;
|
|
assert(current_block != nullptr);
|
|
|
|
*reinterpret_cast<void**>(ptr) = last_freed;
|
|
last_freed = ptr;
|
|
}
|
|
|
|
void SetParameters(size_t item_size, size_t items_per_chunk)
|
|
{
|
|
if (item_size < sizeof(void *)) item_size = sizeof(void *);
|
|
if (this->item_size == item_size && this->items_per_chunk == items_per_chunk) return;
|
|
|
|
assert(current_block == nullptr);
|
|
this->item_size = item_size;
|
|
this->items_per_chunk = items_per_chunk;
|
|
}
|
|
};
|
|
|
|
#endif /* DYN_ARENA_ALLOC_HPP */
|