// Distributed under the MIT license. Copyright (c) 2010, Ivan Vashchaev



#include <stdlib.h>
#include <algorithm>
#include "block_allocator.h"


namespace mc_json{

block_allocator::block_allocator(size_t blocksize): m_head(0), m_blocksize(blocksize)
{
}

block_allocator::~block_allocator()
{
	while (m_head)
	{
		block *temp = m_head->next;
		::free(m_head);
		m_head = temp;
	}
}

void block_allocator::swap(block_allocator &rhs)
{
	std::swap(m_blocksize, rhs.m_blocksize);
	std::swap(m_head, rhs.m_head);
}

void *block_allocator::malloc(size_t size)
{
	if ((m_head && m_head->used + size > m_head->size) || !m_head)
	{
		// calc needed size for allocation
		size_t alloc_size = std::max(sizeof(block) + size, m_blocksize);

		// create new block
		char *buffer = (char *)::malloc(alloc_size);
		block *b = reinterpret_cast<block *>(buffer);
		b->size = alloc_size;
		b->used = sizeof(block);
		b->buffer = buffer;
		b->next = m_head;
		m_head = b;
	}

	void *ptr = m_head->buffer + m_head->used;
	m_head->used += size;
	return ptr;
}

void block_allocator::free()
{
	block_allocator(0).swap(*this);
}

}