#include <malloc.h>

#include <string.h>

#include "CDataPack.h"

#define DATAPACK_INITIAL_SIZE		4//512

CDataPack::CDataPack()

{

	m_pBase = (char *)malloc(DATAPACK_INITIAL_SIZE);

	m_capacity = DATAPACK_INITIAL_SIZE;

	Initialize();

}

CDataPack::~CDataPack()

{

	free(m_pBase);

}

void CDataPack::Initialize()

{

	m_curptr = m_pBase;

	m_size = 0;

}

void CDataPack::CheckSize(size_t typesize)

{

	if (m_curptr - m_pBase + typesize <= m_capacity)

	{

		return;

	}

	size_t pos = m_curptr - m_pBase;

	do

	{

		m_capacity *= 2;

		m_pBase = (char *)realloc(m_pBase, m_capacity);

		m_curptr = m_pBase + pos;

	} while (m_curptr - m_pBase + typesize > m_capacity);

}

void CDataPack::ResetSize()

{

	m_size = 0;

}

size_t CDataPack::CreateMemory(size_t size, void **addr)

{

	CheckSize(sizeof(size_t) + size);

	size_t pos = m_curptr - m_pBase;

	*(size_t *)m_curptr = size;

	m_curptr += sizeof(size_t);

	if (addr)

	{

		*addr = m_curptr;

	}

	m_curptr += size;

	m_size += sizeof(size_t) + size;

	return pos;

}

void CDataPack::PackCell(cell_t cell)

{

	CheckSize(sizeof(size_t) + sizeof(cell_t));

	*(size_t *)m_curptr = sizeof(cell_t);

	m_curptr += sizeof(size_t);

	*(cell_t *)m_curptr = cell;

	m_curptr += sizeof(cell_t);

	m_size += sizeof(size_t) + sizeof(cell_t);

}

void CDataPack::PackFloat(float val)

{

	CheckSize(sizeof(size_t) + sizeof(float));

	*(size_t *)m_curptr = sizeof(float);

	m_curptr += sizeof(size_t);

	*(float *)m_curptr = val;

	m_curptr += sizeof(float);

	m_size += sizeof(size_t) + sizeof(float);

}

void CDataPack::PackString(const char *string)

{

	size_t len = strlen(string);

	size_t maxsize = sizeof(size_t) + len + 1;

	CheckSize(maxsize);

	// Pack the string length first for buffer overrun checking.

	*(size_t *)m_curptr = len;

	m_curptr += sizeof(size_t);

	// Now pack the string.

	memcpy(m_curptr, string, len);

	m_curptr[len] = '\0';

	m_curptr += len + 1;

	m_size += maxsize;

}

void CDataPack::Reset() const

{

	m_curptr = m_pBase;

}

size_t CDataPack::GetPosition() const

{

	return static_cast<size_t>(m_curptr - m_pBase);

}

bool CDataPack::SetPosition(size_t pos) const

{

	if (pos > m_size-1)

	{

		return false;

	}

	m_curptr = m_pBase + pos;

	return true;

}

cell_t CDataPack::ReadCell() const

{

	if (!IsReadable(sizeof(size_t) + sizeof(cell_t)))

	{

		return 0;

	}

	if (*reinterpret_cast<size_t *>(m_curptr) != sizeof(cell_t))

	{

		return 0;

	}

	m_curptr += sizeof(size_t);

	cell_t val = *reinterpret_cast<cell_t *>(m_curptr);

	m_curptr += sizeof(cell_t);

	return val;

}

float CDataPack::ReadFloat() const

{

	if (!IsReadable(sizeof(size_t) + sizeof(float)))

	{

		return 0;

	}

	if (*reinterpret_cast<size_t *>(m_curptr) != sizeof(float))

	{

		return 0;

	}

	m_curptr += sizeof(size_t);

	float val = *reinterpret_cast<float *>(m_curptr);

	m_curptr += sizeof(float);

	return val;

}

bool CDataPack::IsReadable(size_t bytes) const

{

	return (bytes + (m_curptr - m_pBase) > m_size) ? false : true;

}

const char *CDataPack::ReadString(size_t *len) const

{

	if (!IsReadable(sizeof(size_t)))

	{

		return NULL;

	}

	size_t real_len = *(size_t *)m_curptr;

	m_curptr += sizeof(size_t);

	char *str = (char *)m_curptr;

	if ((strlen(str) != real_len) || !(IsReadable(real_len+1)))

	{

		return NULL;

	}

	if (len)

	{

		*len = real_len;

	}

	m_curptr += real_len + 1;

	return str;

}

void *CDataPack::GetMemory() const

{

	return m_curptr;

}

void *CDataPack::ReadMemory(size_t *size) const

{

	if (!IsReadable(sizeof(size_t)))

	{

		return NULL;

	}

	size_t bytecount = *(size_t *)m_curptr;

	m_curptr += sizeof(size_t);

	if (!IsReadable(bytecount))

	{

		return NULL;

	}

	void *ptr = m_curptr;

	if (size)

	{

		*size = bytecount;

	}

	m_curptr += bytecount;

	return ptr;

}