BizHawk/waterbox/ares64/ares/nall/bump-allocator.hpp

105 lines
2.2 KiB
C++

#pragma once
#include <nall/memory.hpp>
namespace nall {
struct bump_allocator {
static constexpr u32 executable = 1 << 0;
static constexpr u32 zero_fill = 1 << 1;
~bump_allocator() {
reset();
}
explicit operator bool() const {
return _memory;
}
auto reset() -> void {
if(_owner) memory::unmap(_memory, _capacity);
_memory = nullptr;
_capacity = 0;
_offset = 0;
_owner = false;
}
auto resize(u32 capacity, u32 flags = 0, u8* buffer = nullptr) -> bool {
reset();
if(buffer) {
if(flags & zero_fill) {
memset(buffer, 0x00, capacity);
}
} else {
buffer = (u8*)memory::map(capacity, flags & executable);
if(!buffer) return false;
_owner = true;
}
_memory = buffer;
_capacity = capacity;
return true;
}
//release all acquired memory
auto release(u32 flags = 0) -> void {
_offset = 0;
if(flags & zero_fill) memset(_memory, 0x00, _capacity);
}
auto capacity() const -> u32 {
return _capacity;
}
auto available() const -> u32 {
return _capacity - _offset;
}
//for allocating blocks of known size
auto acquire(u32 size) -> u8* {
#ifdef DEBUG
struct out_of_memory {};
if((nextOffset(size)) > _capacity) throw out_of_memory{};
#endif
auto memory = _memory + _offset;
_offset = nextOffset(size); //alignment
return memory;
}
//for allocating blocks of unknown size (eg for a dynamic recompiler code block)
auto acquire() -> u8* {
#ifdef DEBUG
struct out_of_memory {};
if(_offset > _capacity) throw out_of_memory{};
#endif
return _memory + _offset;
}
//size can be reserved once the block size is known
auto reserve(u32 size) -> void {
#ifdef DEBUG
struct out_of_memory {};
if((nextOffset(size)) > _capacity) throw out_of_memory{};
#endif
_offset = nextOffset(size); //alignment
}
auto tryAcquire(u32 size, bool reserve = true) -> u8* {
if((nextOffset(size)) > _capacity) return nullptr;
return reserve ? acquire(size) : acquire();
}
private:
auto nextOffset(u32 size) const -> u32 {
return _offset + size + 15 & ~15;
}
u8* _memory = nullptr;
u32 _capacity = 0;
u32 _offset = 0;
bool _owner = false;
};
}