General Purpose library for Freestanding C++ and POSIX systems
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#pragma once
#include "gp_config.hpp"
#include "gp/buffer.hpp"
#include <type_traits>
#include <gp/algorithm/tmp_manip.hpp>
#include "gp/math/integer_math.hpp"
#include "gp/algorithm/min_max.hpp"
namespace gp {
template<typename page_allocator = int>
class arena {
page_allocator allocator;
gp::buffer<char> data;
size_t next;
size_t count;
public:
arena()
: next(0)
, count(0)
, data(gp::buffer<char>(nullptr,nullptr))
{}
arena(size_t sz)
: next(0)
, count(0)
, data(nullptr,nullptr)
{
if constexpr (gp::has_allocator_interface<page_allocator>::value)
{
if(sz!=0)
{
auto v=allocator.allocate(sz);
if(v!=nullptr)
{
data=gp::buffer<char>(reinterpret_cast<char*>(v),reinterpret_cast<char*>(v)+sz);
}
}
}
}
arena(char* pos,size_t sz)
: next(0)
, count(0)
, data(pos,pos+sz)
{}
void* allocate(size_t sz)
{
size_t align = gp::min((1 << gp::math::log2(sz)), 16);
size_t padding = align - (reinterpret_cast<uintptr_t>(data.begin().data + next)) % align;
auto ret=data.begin()+padding+next;
if(data.contains(ret))
{
count++;
next+=padding+sz;
return ret.data;
}
else
{
return nullptr;
}
}
constexpr bool try_reallocate(void*, size_t) {
return false;
}
bool deallocate(void* ptr)
{
if(data.contains((char*)ptr))
{
count--;
if(count==0)
{
for(auto& i : data)
{
i=0;
}
next=0;
}
return true;
}
return false;
}
~arena()
{
if constexpr(gp::has_allocator_interface<page_allocator>::value)
{
allocator.deallocate(&data[0]);
}
}
};
}