serialize.h

/*
    serialize

    Copyright © 2016 - 2024, Mas Bandwidth LLC.

    Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

        1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

        2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer
           in the documentation and/or other materials provided with the distribution.

        3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived
           from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
    INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
    WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
    USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifndef SERIALIZE_H
#define SERIALIZE_H

/** @file */

#ifndef serialize_assert
#include <assert.h>
#define serialize_assert assert
#endif // #ifndef serialize_assert

#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS
#endif

#if !defined(SERIALIZE_DEBUG) && !defined(SERIALIZE_RELEASE)
#if defined(NDEBUG)
#define SERIALIZE_RELEASE
#else
#define SERIALIZE_DEBUG
#endif
#elif defined(SERIALIZE_DEBUG) && defined(SERIALIZE_RELEASE)
#error Can only define one of debug & release
#endif

#if !defined(SERIALIZE_LITTLE_ENDIAN ) && !defined( SERIALIZE_BIG_ENDIAN )

  #ifdef __BYTE_ORDER__
    #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
      #define SERIALIZE_LITTLE_ENDIAN 1
    #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
      #define SERIALIZE_BIG_ENDIAN 1
    #else
      #error Unknown machine endianess detected. User needs to define SERIALIZE_LITTLE_ENDIAN or SERIALIZE_BIG_ENDIAN.
    #endif // __BYTE_ORDER__

  // Detect with GLIBC's endian.h
  #elif defined(__GLIBC__)
    #include <endian.h>
    #if (__BYTE_ORDER == __LITTLE_ENDIAN)
      #define SERIALIZE_LITTLE_ENDIAN 1
    #elif (__BYTE_ORDER == __BIG_ENDIAN)
      #define SERIALIZE_BIG_ENDIAN 1
    #else
      #error Unknown machine endianess detected. User needs to define SERIALIZE_LITTLE_ENDIAN or SERIALIZE_BIG_ENDIAN.
    #endif // __BYTE_ORDER

  // Detect with _LITTLE_ENDIAN and _BIG_ENDIAN macro
  #elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
    #define SERIALIZE_LITTLE_ENDIAN 1
  #elif defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN)
    #define SERIALIZE_BIG_ENDIAN 1

  // Detect with architecture macros
  #elif    defined(__sparc)     || defined(__sparc__)                           \
        || defined(_POWER)      || defined(__powerpc__)                         \
        || defined(__ppc__)     || defined(__hpux)      || defined(__hppa)      \
        || defined(_MIPSEB)     || defined(_POWER)      || defined(__s390__)
    #define SERIALIZE_BIG_ENDIAN 1
  #elif    defined(__i386__)    || defined(__alpha__)   || defined(__ia64)      \
        || defined(__ia64__)    || defined(_M_IX86)     || defined(_M_IA64)     \
        || defined(_M_ALPHA)    || defined(__amd64)     || defined(__amd64__)   \
        || defined(_M_AMD64)    || defined(__x86_64)    || defined(__x86_64__)  \
        || defined(_M_X64)      || defined(__bfin__)
    #define SERIALIZE_LITTLE_ENDIAN 1
  #elif defined(_MSC_VER) && defined(_M_ARM)
    #define SERIALIZE_LITTLE_ENDIAN 1
  #else
    #error Unknown machine endianess detected. User needs to define SERIALIZE_LITTLE_ENDIAN or SERIALIZE_BIG_ENDIAN.
  #endif
#endif

#ifndef SERIALIZE_LITTLE_ENDIAN
#define SERIALIZE_LITTLE_ENDIAN 0
#endif

#ifndef SERIALIZE_BIG_ENDIAN
#define SERIALIZE_BIG_ENDIAN 0
#endif

#ifdef _MSC_VER
#pragma warning( disable : 4127 )
#pragma warning( disable : 4244 )
#endif // #ifdef _MSC_VER

#include <stdint.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <memory.h>
#include <math.h>
#include <inttypes.h>

namespace serialize 
{
    /**
        Calculates the population count of an unsigned 32 bit integer at compile time.
        Population count is the number of bits in the integer that set to 1.
        See "Hacker's Delight" and http://www.hackersdelight.org/hdcodetxt/popArrayHS.c.txt
        @see serialize::Log2
        @see serialize::BitsRequired
     */

    template <uint32_t x> struct PopCount
    {
        enum {   a = x - ( ( x >> 1 )       & 0x55555555 ),
                 b =   ( ( ( a >> 2 )       & 0x33333333 ) + ( a & 0x33333333 ) ),
                 c =   ( ( ( b >> 4 ) + b ) & 0x0f0f0f0f ),
                 d =   c + ( c >> 8 ),
                 e =   d + ( d >> 16 ),

            result = e & 0x0000003f
        };
    };

    /**
        Calculates the log 2 of an unsigned 32 bit integer at compile time.
        @see serialize::Log2
        @see serialize::BitsRequired
     */

    template <uint32_t x> struct Log2
    {
        enum {   a = x | ( x >> 1 ),
                 b = a | ( a >> 2 ),
                 c = b | ( b >> 4 ),
                 d = c | ( c >> 8 ),
                 e = d | ( d >> 16 ),
                 f = e >> 1,

            result = PopCount<f>::result
        };
    };

    /**
        Calculates the number of bits required to serialize an integer value in [min,max] at compile time.
        @see Log2
        @see PopCount
     */

    template <int64_t min, int64_t max> struct BitsRequired
    {
        static const uint32_t result = ( min == max ) ? 0 : ( Log2<uint32_t(max-min)>::result + 1 );
    };

    /**
        Calculates the population count of an unsigned 32 bit integer.
        The population count is the number of bits in the integer set to 1.
        @param x The input integer value.
        @returns The number of bits set to 1 in the input value.
     */

    inline uint32_t popcount( uint32_t x )
    {
#ifdef __GNUC__
        return __builtin_popcount( x );
#else // #ifdef __GNUC__
        const uint32_t a = x - ( ( x >> 1 )       & 0x55555555 );
        const uint32_t b =   ( ( ( a >> 2 )       & 0x33333333 ) + ( a & 0x33333333 ) );
        const uint32_t c =   ( ( ( b >> 4 ) + b ) & 0x0f0f0f0f );
        const uint32_t d =   c + ( c >> 8 );
        const uint32_t e =   d + ( d >> 16 );
        const uint32_t result = e & 0x0000003f;
        return result;
#endif // #ifdef __GNUC__
    }

    /**
        Calculates the log base 2 of an unsigned 32 bit integer.
        @param x The input integer value.
        @returns The log base 2 of the input.
     */

    inline uint32_t log2( uint32_t x )
    {
        const uint32_t a = x | ( x >> 1 );
        const uint32_t b = a | ( a >> 2 );
        const uint32_t c = b | ( b >> 4 );
        const uint32_t d = c | ( c >> 8 );
        const uint32_t e = d | ( d >> 16 );
        const uint32_t f = e >> 1;
        return popcount( f );
    }

    /**
        Calculates the number of bits required to serialize an integer in range [min,max].
        @param min The minimum value.
        @param max The maximum value.
        @returns The number of bits required to serialize the integer.
     */

    inline int bits_required( uint32_t min, uint32_t max )
    {
#ifdef __GNUC__
        return ( min == max ) ? 0 : 32 - __builtin_clz( max - min );
#else // #ifdef __GNUC__
        return ( min == max ) ? 0 : log2( max - min ) + 1;
#endif // #ifdef __GNUC__
    }

    /**
        Reverse the order of bytes in a 64 bit integer.
        @param value The input value.
        @returns The input value with the byte order reversed.
     */

    inline uint64_t bswap( uint64_t value )
    {
#ifdef __GNUC__
        return __builtin_bswap64( value );
#else // #ifdef __GNUC__
        value = ( value & 0x00000000FFFFFFFF ) << 32 | ( value & 0xFFFFFFFF00000000 ) >> 32;
        value = ( value & 0x0000FFFF0000FFFF ) << 16 | ( value & 0xFFFF0000FFFF0000 ) >> 16;
        value = ( value & 0x00FF00FF00FF00FF ) << 8  | ( value & 0xFF00FF00FF00FF00 ) >> 8;
        return value;
#endif // #ifdef __GNUC__
    }

    /**
        Reverse the order of bytes in a 32 bit integer.
        @param value The input value.
        @returns The input value with the byte order reversed.
     */

    inline uint32_t bswap( uint32_t value )
    {
#ifdef __GNUC__
        return __builtin_bswap32( value );
#else // #ifdef __GNUC__
        return ( value & 0x000000ff ) << 24 | ( value & 0x0000ff00 ) << 8 | ( value & 0x00ff0000 ) >> 8 | ( value & 0xff000000 ) >> 24;
#endif // #ifdef __GNUC__
    }

    /**
        Reverse the order of bytes in a 16 bit integer.
        @param value The input value.
        @returns The input value with the byte order reversed.
     */

    inline uint16_t bswap( uint16_t value )
    {
        return ( value & 0x00ff ) << 8 | ( value & 0xff00 ) >> 8;
    }

    /**
        Template to convert an integer value from local byte order to network byte order.
        IMPORTANT: Because most machines are little endian, serialize defines network byte order to be little endian.
        @param value The input value in local byte order. Supported integer types: uint64_t, uint32_t, uint16_t.
        @returns The input value converted to network byte order. If this processor is little endian the output is the same as the input. If the processor is big endian, the output is the input byte swapped.
        @see serialize::bswap
     */

    template <typename T> T host_to_network( T value )
    {
#if SERIALIZE_BIG_ENDIAN
        return bswap( value );
#else // #if SERIALIZE_BIG_ENDIAN
        return value;
#endif // #if SERIALIZE_BIG_ENDIAN
    }

    /**
        Template to convert an integer value from network byte order to local byte order.
        IMPORTANT: Because most machines are little endian, serialize defines network byte order to be little endian.
        @param value The input value in network byte order. Supported integer types: uint64_t, uint32_t, uint16_t.
        @returns The input value converted to local byte order. If this processor is little endian the output is the same as the input. If the processor is big endian, the output is the input byte swapped.
        @see serialize::bswap
     */

    template <typename T> T network_to_host( T value )
    {
#if SERIALIZE_BIG_ENDIAN
        return bswap( value );
#else // #if SERIALIZE_BIG_ENDIAN
        return value;
#endif // #if SERIALIZE_BIG_ENDIAN
    }

    /**
        Convert a signed integer to an unsigned integer with zig-zag encoding.
        0,-1,+1,-2,+2... becomes 0,1,2,3,4 ...
        @param n The input value.
        @returns The input value converted from signed to unsigned with zig-zag encoding.
     */

    inline int signed_to_unsigned( int n )
    {
        return ( n << 1 ) ^ ( n >> 31 );
    }

    /**
        Convert an unsigned integer to as signed integer with zig-zag encoding.
        0,1,2,3,4... becomes 0,-1,+1,-2,+2...
        @param n The input value.
        @returns The input value converted from unsigned to signed with zig-zag encoding.
     */

    inline int unsigned_to_signed( uint32_t n )
    {
        return ( n >> 1 ) ^ ( -int32_t( n & 1 ) );
    }

    template <typename T> T clamp( const T & value, const T & a, const T & b )
    {
        if ( value < a )
            return a;
        else if ( value > b )
            return b;
        else
            return value;
    }

    /**
        Bitpacks unsigned integer values to a buffer.
        Integer bit values are written to a 64 bit scratch value from right to left.
        Once the low 32 bits of the scratch is filled with bits it is flushed to memory as a dword and the scratch value is shifted right by 32.
        The bit stream is written to memory in little endian order, which is considered network byte order for this library.
        @see BitReader
     */

    class BitWriter
    {
    public:

        /**
            Bit writer constructor.
            Creates a bit writer object to write to the specified buffer.
            @param data The pointer to the buffer to fill with bitpacked data.
            @param bytes The size of the buffer in bytes. Must be a multiple of 4, because the bitpacker reads and writes memory as dwords, not bytes.
         */

        BitWriter( void * data, int bytes ) : m_data( (uint32_t*) data ), m_numWords( bytes / 4 )
        {
            serialize_assert( data );
            serialize_assert( ( bytes % 4 ) == 0 );
            m_numBits = m_numWords * 32;
            m_bitsWritten = 0;
            m_wordIndex = 0;
            m_scratch = 0;
            m_scratchBits = 0;
        }

        /**
            Write bits to the buffer.
            Bits are written to the buffer as-is, without padding to nearest byte. Will assert if you try to write past the end of the buffer.
            A boolean value writes just 1 bit to the buffer, a value in range [0,31] can be written with just 5 bits and so on.
            IMPORTANT: When you have finished writing to your buffer, take care to call BitWrite::FlushBits, otherwise the last dword of data will not get flushed to memory!
            @param value The integer value to write to the buffer. Must be in [0,(1<<bits)-1].
            @param bits The number of bits to encode in [1,32].
            @see BitReader::ReadBits
         */

        void WriteBits( uint32_t value, int bits )
        {
            serialize_assert( bits > 0 );
            serialize_assert( bits <= 32 );
            serialize_assert( m_bitsWritten + bits <= m_numBits );
            serialize_assert( uint64_t( value ) <= ( ( 1ULL << bits ) - 1 ) );

            m_scratch |= uint64_t( value ) << m_scratchBits;

            m_scratchBits += bits;

            if ( m_scratchBits >= 32 )
            {
                serialize_assert( m_wordIndex < m_numWords );
                m_data[m_wordIndex] = host_to_network( uint32_t( m_scratch & 0xFFFFFFFF ) );
                m_scratch >>= 32;
                m_scratchBits -= 32;
                m_wordIndex++;
            }

            m_bitsWritten += bits;
        }

        /**
            Write an alignment to the bit stream, padding zeros so the bit index becomes is a multiple of 8.
            This is useful if you want to write some data to a packet that should be byte aligned. For example, an array of bytes, or a string.
            IMPORTANT: If the current bit index is already a multiple of 8, nothing is written.
            @see BitReader::ReadAlign
         */

        void WriteAlign()
        {
            const int remainderBits = m_bitsWritten % 8;

            if ( remainderBits != 0 )
            {
                uint32_t zero = 0;
                WriteBits( zero, 8 - remainderBits );
                serialize_assert( ( m_bitsWritten % 8 ) == 0 );
            }
        }

        /**
            Write an array of bytes to the bit stream.
            Use this when you have to copy a large block of data into your bitstream.
            Faster than just writing each byte to the bit stream via BitWriter::WriteBits( value, 8 ), because it aligns to byte index and copies into the buffer without bitpacking.
            @param data The byte array data to write to the bit stream.
            @param bytes The number of bytes to write.
            @see BitReader::ReadBytes
         */

        void WriteBytes( const uint8_t * data, int bytes )
        {
            serialize_assert( GetAlignBits() == 0 );
            serialize_assert( m_bitsWritten + bytes * 8 <= m_numBits );
            serialize_assert( ( m_bitsWritten % 32 ) == 0 || ( m_bitsWritten % 32 ) == 8 || ( m_bitsWritten % 32 ) == 16 || ( m_bitsWritten % 32 ) == 24 );

            int headBytes = ( 4 - ( m_bitsWritten % 32 ) / 8 ) % 4;
            if ( headBytes > bytes )
                headBytes = bytes;
            for ( int i = 0; i < headBytes; ++i )
                WriteBits( data[i], 8 );
            if ( headBytes == bytes )
                return;

            FlushBits();

            serialize_assert( GetAlignBits() == 0 );

            int numWords = ( bytes - headBytes ) / 4;
            if ( numWords > 0 )
            {
                serialize_assert( ( m_bitsWritten % 32 ) == 0 );
                memcpy( &m_data[m_wordIndex], data + headBytes, numWords * 4 );
                m_bitsWritten += numWords * 32;
                m_wordIndex += numWords;
                m_scratch = 0;
            }

            serialize_assert( GetAlignBits() == 0 );

            int tailStart = headBytes + numWords * 4;
            int tailBytes = bytes - tailStart;
            serialize_assert( tailBytes >= 0 && tailBytes < 4 );
            for ( int i = 0; i < tailBytes; ++i )
                WriteBits( data[tailStart+i], 8 );

            serialize_assert( GetAlignBits() == 0 );

            serialize_assert( headBytes + numWords * 4 + tailBytes == bytes );
        }

        /**
            Flush any remaining bits to memory.
            Call this once after you've finished writing bits to flush the last dword of scratch to memory!
            @see BitWriter::WriteBits
         */

        void FlushBits()
        {
            if ( m_scratchBits != 0 )
            {
                serialize_assert( m_scratchBits <= 32 );
                serialize_assert( m_wordIndex < m_numWords );
                m_data[m_wordIndex] = host_to_network( uint32_t( m_scratch & 0xFFFFFFFF ) );
                m_scratch >>= 32;
                m_scratchBits = 0;
                m_wordIndex++;
            }
        }

        /**
            How many align bits would be written, if we were to write an align right now?
            @returns Result in [0,7], where 0 is zero bits required to align (already aligned) and 7 is worst case.
         */

        int GetAlignBits() const
        {
            return ( 8 - ( m_bitsWritten % 8 ) ) % 8;
        }

        /**
            How many bits have we written so far?
            @returns The number of bits written to the bit buffer.
         */

        int GetBitsWritten() const
        {
            return m_bitsWritten;
        }

        /**
            How many bits are still available to write?
            For example, if the buffer size is 4, we have 32 bits available to write, if we have already written 10 bytes then 22 are still available to write.
            @returns The number of bits available to write.
         */

        int GetBitsAvailable() const
        {
            return m_numBits - m_bitsWritten;
        }

        /**
            Get a pointer to the data written by the bit writer.
            Corresponds to the data block passed in to the constructor.
            @returns Pointer to the data written by the bit writer.
         */

        const uint8_t * GetData() const
        {
            return (uint8_t*) m_data;
        }

        /**
            The number of bytes flushed to memory.
            This is effectively the size of the packet that you should send after you have finished bitpacking values with this class.
            The returned value is not always a multiple of 4, even though we flush dwords to memory. You won't miss any data in this case because the order of bits written is designed to work with the little endian memory layout.
            IMPORTANT: Make sure you call BitWriter::FlushBits before calling this method, otherwise you risk missing the last dword of data.
         */

        int GetBytesWritten() const
        {
            return ( m_bitsWritten + 7 ) / 8;
        }

    private:

        uint32_t * m_data;              ///< The buffer we are writing to, as a uint32_t * because we're writing dwords at a time.
        uint64_t m_scratch;             ///< The scratch value where we write bits to (right to left). 64 bit for overflow. Once # of bits in scratch is >= 32, the low 32 bits are flushed to memory.
        int m_numBits;                  ///< The number of bits in the buffer. This is equivalent to the size of the buffer in bytes multiplied by 8. Note that the buffer size must always be a multiple of 4.
        int m_numWords;                 ///< The number of words in the buffer. This is equivalent to the size of the buffer in bytes divided by 4. Note that the buffer size must always be a multiple of 4.
        int m_bitsWritten;              ///< The number of bits written so far.
        int m_wordIndex;                ///< The current word index. The next word flushed to memory will be at this index in m_data.
        int m_scratchBits;              ///< The number of bits in scratch. When this is >= 32, the low 32 bits of scratch is flushed to memory as a dword and scratch is shifted right by 32.
    };

    /**
        Reads bit packed integer values from a buffer.
        Relies on the user reconstructing the exact same set of bit reads as bit writes when the buffer was written. This is an unattributed bitpacked binary stream!
        Implementation: 32 bit dwords are read in from memory to the high bits of a scratch value as required. The user reads off bit values from the scratch value from the right, after which the scratch value is shifted by the same number of bits.
     */

    class BitReader
    {
    public:

        /**
            Bit reader constructor.
            Non-multiples of four buffer sizes are supported, as this naturally tends to occur when packets are read from the network.
            However, actual buffer allocated for the packet data must round up at least to the next 4 bytes in memory, because the bit reader reads dwords from memory not bytes.
            @param data Pointer to the bitpacked data to read.
            @param bytes The number of bytes of bitpacked data to read.
            @see BitWriter
         */

#ifdef SERIALIZE_DEBUG
        BitReader( const void * data, int bytes ) : m_data( (const uint32_t*) data ), m_numBytes( bytes ), m_numWords( ( bytes + 3 ) / 4)
#else // #ifdef SERIALIZE_DEBUG
        BitReader( const void * data, int bytes ) : m_data( (const uint32_t*) data ), m_numBytes( bytes )
#endif // #ifdef SERIALIZE_DEBUG
        {
            serialize_assert( data );
            m_numBits = m_numBytes * 8;
            m_bitsRead = 0;
            m_scratch = 0;
            m_scratchBits = 0;
            m_wordIndex = 0;
        }

        /**
            Would the bit reader would read past the end of the buffer if it read this many bits?
            @param bits The number of bits that would be read.
            @returns True if reading the number of bits would read past the end of the buffer.
         */

        bool WouldReadPastEnd( int bits ) const
        {
            return m_bitsRead + bits > m_numBits;
        }

        /**
            Read bits from the bit buffer.
            This function will assert in debug builds if this read would read past the end of the buffer.
            In production situations, the higher level ReadStream takes care of checking all packet data and never calling this function if it would read past the end of the buffer.
            @param bits The number of bits to read in [1,32].
            @returns The integer value read in range [0,(1<<bits)-1].
            @see BitReader::WouldReadPastEnd
            @see BitWriter::WriteBits
         */

        uint32_t ReadBits( int bits )
        {
            serialize_assert( bits > 0 );
            serialize_assert( bits <= 32 );
            serialize_assert( m_bitsRead + bits <= m_numBits );

            m_bitsRead += bits;

            serialize_assert( m_scratchBits >= 0 && m_scratchBits <= 64 );

            if ( m_scratchBits < bits )
            {
#ifdef SERIALIZE_DEBUG
                serialize_assert( m_wordIndex < m_numWords );
#endif // SERIALIZE_DEBUG
                m_scratch |= uint64_t( network_to_host( m_data[m_wordIndex] ) ) << m_scratchBits;
                m_scratchBits += 32;
                m_wordIndex++;
            }

            serialize_assert( m_scratchBits >= bits );

            const uint32_t output = m_scratch & ( (uint64_t(1)<<bits) - 1 );

            m_scratch >>= bits;
            m_scratchBits -= bits;

            return output;
        }

        /**
            Read an align.
            Call this on read to correspond to a WriteAlign call when the bitpacked buffer was written.
            This makes sure we skip ahead to the next aligned byte index. As a safety check, we verify that the padding to next byte is zero bits and return false if that's not the case.
            This will typically abort packet read. Just another safety measure...
            @returns True if we successfully read an align and skipped ahead past zero pad, false otherwise (probably means, no align was written to the stream).
            @see BitWriter::WriteAlign
         */

        bool ReadAlign()
        {
            const int remainderBits = m_bitsRead % 8;
            if ( remainderBits != 0 )
            {
                uint32_t value = ReadBits( 8 - remainderBits );
                serialize_assert( m_bitsRead % 8 == 0 );
                if ( value != 0 )
                    return false;
            }
            return true;
        }

        /**
            Read bytes from the bitpacked data.
            @see BitWriter::WriteBytes
         */

        void ReadBytes( uint8_t * data, int bytes )
        {
            serialize_assert( GetAlignBits() == 0 );
            serialize_assert( m_bitsRead + bytes * 8 <= m_numBits );
            serialize_assert( ( m_bitsRead % 32 ) == 0 || ( m_bitsRead % 32 ) == 8 || ( m_bitsRead % 32 ) == 16 || ( m_bitsRead % 32 ) == 24 );

            int headBytes = ( 4 - ( m_bitsRead % 32 ) / 8 ) % 4;
            if ( headBytes > bytes )
                headBytes = bytes;
            for ( int i = 0; i < headBytes; ++i )
                data[i] = (uint8_t) ReadBits( 8 );
            if ( headBytes == bytes )
                return;

            serialize_assert( GetAlignBits() == 0 );

            int numWords = ( bytes - headBytes ) / 4;
            if ( numWords > 0 )
            {
                serialize_assert( ( m_bitsRead % 32 ) == 0 );
                memcpy( data + headBytes, &m_data[m_wordIndex], numWords * 4 );
                m_bitsRead += numWords * 32;
                m_wordIndex += numWords;
                m_scratchBits = 0;
            }

            serialize_assert( GetAlignBits() == 0 );

            int tailStart = headBytes + numWords * 4;
            int tailBytes = bytes - tailStart;
            serialize_assert( tailBytes >= 0 && tailBytes < 4 );
            for ( int i = 0; i < tailBytes; ++i )
                data[tailStart+i] = (uint8_t) ReadBits( 8 );

            serialize_assert( GetAlignBits() == 0 );

            serialize_assert( headBytes + numWords * 4 + tailBytes == bytes );
        }

        /**
            How many align bits would be read, if we were to read an align right now?
            @returns Result in [0,7], where 0 is zero bits required to align (already aligned) and 7 is worst case.
         */

        int GetAlignBits() const
        {
            return ( 8 - m_bitsRead % 8 ) % 8;
        }

        /**
            How many bits have we read so far?
            @returns The number of bits read from the bit buffer so far.
         */

        int GetBitsRead() const
        {
            return m_bitsRead;
        }

        /**
            How many bits are still available to read?
            For example, if the buffer size is 4, we have 32 bits available to read, if we have already written 10 bytes then 22 are still available.
            @returns The number of bits available to read.
         */

        int GetBitsRemaining() const
        {
            return m_numBits - m_bitsRead;
        }

    private:

        const uint32_t * m_data;            ///< The bitpacked data we're reading as a dword array.
        uint64_t m_scratch;                 ///< The scratch value. New data is read in 32 bits at a top to the left of this buffer, and data is read off to the right.
        int m_numBits;                      ///< Number of bits to read in the buffer. Of course, we can't *really* know this so it's actually m_numBytes * 8.
        int m_numBytes;                     ///< Number of bytes to read in the buffer. We know this, and this is the non-rounded up version.
#ifdef SERIALIZE_DEBUG
        int m_numWords;                     ///< Number of words to read in the buffer. This is rounded up to the next word if necessary.
#endif // #ifdef SERIALIZE_DEBUG
        int m_bitsRead;                     ///< Number of bits read from the buffer so far.
        int m_scratchBits;                  ///< Number of bits currently in the scratch value. If the user wants to read more bits than this, we have to go fetch another dword from memory.
        int m_wordIndex;                    ///< Index of the next word to read from memory.
    };

    /**
        Functionality common to all stream classes.
     */

    class BaseStream
    {
    public:

        /**
            Base stream constructor.
         */

        explicit BaseStream() : m_context( NULL ), m_allocator( NULL ) {}

        /**
            Set a context on the stream.
            Contexts are used by the library supply data that is needed to read and write packets.
            Specifically, this context is used by the connection to supply data needed to read and write connection packets.
         */

        void SetContext( void * context )
        {
            m_context = context;
        }

        /**
            Get the context pointer set on the stream.

            @returns The context pointer. May be NULL.
         */

        void * GetContext() const
        {
            return m_context;
        }

        /**
            Set an allocator pointer on the stream.
            This can be helpful if you want to perform allocations within serialize functions.
         */

        void SetAllocator( void * allocator )
        {
            m_allocator = allocator;
        }

        /**
            Get the allocator pointer set on the stream.

            @returns The allocator pointer. May be NULL.
         */

        void * GetAllocator() const
        {
            return m_allocator;
        }

    private:

        void * m_context;                           ///< The context pointer set on the stream. May be NULL.
        void * m_allocator;                         ///< The allocator pointer set on the stream. May be NULL.
    };

    /**
        Stream class for writing bitpacked data.
        This class is a wrapper around the bit writer class. Its purpose is to provide unified interface for reading and writing.
        You can determine if you are writing to a stream by calling Stream::IsWriting inside your templated serialize method.
        This is evaluated at compile time, letting the compiler generate optimized serialize functions without the hassle of maintaining separate read and write functions.
        IMPORTANT: Generally, you don't call methods on this class directly. Use the serialize_* macros instead.
        @see BitWriter
     */

    class WriteStream : public BaseStream
    {
    public:

        enum { IsWriting = 1 };
        enum { IsReading = 0 };

        /**
            Write stream constructor.
            @param buffer The buffer to write to.
            @param bytes The number of bytes in the buffer. Must be a multiple of four.
            @param allocator The allocator to use for stream allocations. This lets you dynamically allocate memory as you read and write packets.
         */

        WriteStream( uint8_t * buffer, int bytes ) : m_writer( buffer, bytes ) {}

        /**
            Serialize an integer (write).
            @param value The integer value in [min,max].
            @param min The minimum value.
            @param max The maximum value.
            @returns Always returns true. All checking is performed by debug asserts only on write.
         */

        bool SerializeInteger( int32_t value, int32_t min, int32_t max )
        {
            serialize_assert( min < max );
            serialize_assert( value >= min );
            serialize_assert( value <= max );
            const int bits = bits_required( min, max );
            uint32_t unsigned_value = value - min;
            m_writer.WriteBits( unsigned_value, bits );
            return true;
        }

        /**
            Serialize a number of bits (write).
            @param value The unsigned integer value to serialize. Must be in range [0,(1<<bits)-1].
            @param bits The number of bits to write in [1,32].
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeBits( uint32_t value, int bits )
        {
            serialize_assert( bits > 0 );
            serialize_assert( bits <= 32 );
            m_writer.WriteBits( value, bits );
            return true;
        }

        /**
            Serialize an array of bytes (write).
            @param data Array of bytes to be written.
            @param bytes The number of bytes to write.
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeBytes( const uint8_t * data, int bytes )
        {
            serialize_assert( data );
            serialize_assert( bytes >= 0 );
            SerializeAlign();
            m_writer.WriteBytes( data, bytes );
            return true;
        }

        /**
            Serialize an align (write).
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeAlign()
        {
            m_writer.WriteAlign();
            return true;
        }

        /**
            If we were to write an align right now, how many bits would be required?
            @returns The number of zero pad bits required to achieve byte alignment in [0,7].
         */

        int GetAlignBits() const
        {
            return m_writer.GetAlignBits();
        }

        /**
            Flush the stream to memory after you finish writing.
            Always call this after you finish writing and before you call WriteStream::GetData, or you'll potentially truncate the last dword of data you wrote.
            @see BitWriter::FlushBits
         */

        void Flush()
        {
            m_writer.FlushBits();
        }

        /**
            Get a pointer to the data written by the stream.
            IMPORTANT: Call WriteStream::Flush before you call this function!
            @returns A pointer to the data written by the stream
         */

        const uint8_t * GetData() const
        {
            return m_writer.GetData();
        }

        /**
            How many bytes have been written so far?
            @returns Number of bytes written. This is effectively the packet size.
         */

        int GetBytesProcessed() const
        {
            return m_writer.GetBytesWritten();
        }

        /**
            Get number of bits written so far.
            @returns Number of bits written.
         */

        int GetBitsProcessed() const
        {
            return m_writer.GetBitsWritten();
        }

    private:

        BitWriter m_writer;                 ///< The bit writer used for all bitpacked write operations.
    };

    /**
        Stream class for reading bitpacked data.
        This class is a wrapper around the bit reader class. Its purpose is to provide unified interface for reading and writing.
        You can determine if you are reading from a stream by calling Stream::IsReading inside your templated serialize method.
        This is evaluated at compile time, letting the compiler generate optimized serialize functions without the hassle of maintaining separate read and write functions.
        IMPORTANT: Generally, you don't call methods on this class directly. Use the serialize_* macros instead.
        @see BitReader
     */

    class ReadStream : public BaseStream
    {
    public:

        enum { IsWriting = 0 };
        enum { IsReading = 1 };

        /**
            Read stream constructor.
            @param buffer The buffer to read from.
            @param bytes The number of bytes in the buffer. May be a non-multiple of four, however if it is, the underlying buffer allocated should be large enough to read the any remainder bytes as a dword.
            @param allocator The allocator to use for stream allocations. This lets you dynamically allocate memory as you read and write packets.
         */

        ReadStream( const uint8_t * buffer, int bytes ) : m_reader( buffer, bytes ) {}

        /**
            Serialize an integer (read).
            @param value The integer value read is stored here. It is guaranteed to be in [min,max] if this function succeeds.
            @param min The minimum allowed value.
            @param max The maximum allowed value.
            @returns Returns true if the serialize succeeded and the value is in the correct range. False otherwise.
         */

        bool SerializeInteger( int32_t & value, int32_t min, int32_t max )
        {
            serialize_assert( min < max );
            const int bits = bits_required( min, max );
            if ( m_reader.WouldReadPastEnd( bits ) )
                return false;
            uint32_t unsigned_value = m_reader.ReadBits( bits );
            value = (int32_t) unsigned_value + min;
            return true;
        }

        /**
            Serialize a number of bits (read).
            @param value The integer value read is stored here. Will be in range [0,(1<<bits)-1].
            @param bits The number of bits to read in [1,32].
            @returns Returns true if the serialize read succeeded, false otherwise.
         */

        bool SerializeBits( uint32_t & value, int bits )
        {
            serialize_assert( bits > 0 );
            serialize_assert( bits <= 32 );
            if ( m_reader.WouldReadPastEnd( bits ) )
                return false;
            uint32_t read_value = m_reader.ReadBits( bits );
            value = read_value;
            return true;
        }

        /**
            Serialize an array of bytes (read).
            @param data Array of bytes to read.
            @param bytes The number of bytes to read.
            @returns Returns true if the serialize read succeeded. False otherwise.
         */

        bool SerializeBytes( uint8_t * data, int bytes )
        {
            if ( !SerializeAlign() )
                return false;
            if ( m_reader.WouldReadPastEnd( bytes * 8 ) )
                return false;
            m_reader.ReadBytes( data, bytes );
            return true;
        }

        /**
            Serialize an align (read).
            @returns Returns true if the serialize read succeeded. False otherwise.
         */

        bool SerializeAlign()
        {
            const int alignBits = m_reader.GetAlignBits();
            if ( m_reader.WouldReadPastEnd( alignBits ) )
                return false;
            if ( !m_reader.ReadAlign() )
                return false;
            return true;
        }

        /**
            If we were to read an align right now, how many bits would we need to read?
            @returns The number of zero pad bits required to achieve byte alignment in [0,7].
         */

        int GetAlignBits() const
        {
            return m_reader.GetAlignBits();
        }

        /**
            Get number of bits read so far.
            @returns Number of bits read.
         */

        int GetBitsProcessed() const
        {
            return m_reader.GetBitsRead();
        }

        /**
            How many bytes have been read so far?
            @returns Number of bytes read. Effectively this is the number of bits read, rounded up to the next byte where necessary.
         */

        int GetBytesProcessed() const
        {
            return ( m_reader.GetBitsRead() + 7 ) / 8;
        }

    private:

        BitReader m_reader;             ///< The bit reader used for all bitpacked read operations.
    };

    /**
        Stream class for estimating how many bits it would take to serialize something.
        This class acts like a bit writer (IsWriting is 1, IsReading is 0), but instead of writing data, it counts how many bits would be written.
        Note that when the serialization includes alignment to byte (see MeasureStream::SerializeAlign), this is an estimate and not an exact measurement. The estimate is guaranteed to be conservative.
        @see BitWriter
        @see BitReader
     */

    class MeasureStream : public BaseStream
    {
    public:

        enum { IsWriting = 1 };
        enum { IsReading = 0 };

        /**
            Measure stream constructor.
            @param allocator The allocator to use for stream allocations. This lets you dynamically allocate memory as you read and write packets.
         */

        explicit MeasureStream() : m_bitsWritten(0) {}

        /**
            Serialize an integer (measure).
            @param value The integer value to write. Not actually used or checked.
            @param min The minimum value.
            @param max The maximum value.
            @returns Always returns true. All checking is performed by debug asserts only on measure.
         */

        bool SerializeInteger( int32_t value, int32_t min, int32_t max )
        {
            (void) value;
            serialize_assert( min < max );
            serialize_assert( value >= min );
            serialize_assert( value <= max );
            const int bits = bits_required( min, max );
            m_bitsWritten += bits;
            return true;
        }

        /**
            Serialize a number of bits (write).
            @param value The unsigned integer value to serialize. Not actually used or checked.
            @param bits The number of bits to write in [1,32].
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeBits( uint32_t value, int bits )
        {
            (void) value;
            serialize_assert( bits > 0 );
            serialize_assert( bits <= 32 );
            m_bitsWritten += bits;
            return true;
        }

        /**
            Serialize an array of bytes (measure).
            @param data Array of bytes to 'write'. Not actually used.
            @param bytes The number of bytes to 'write'.
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeBytes( const uint8_t * data, int bytes )
        {
            (void) data;
            SerializeAlign();
            m_bitsWritten += bytes * 8;
            return true;
        }

        /**
            Serialize an align (measure).
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeAlign()
        {
            const int alignBits = GetAlignBits();
            m_bitsWritten += alignBits;
            return true;
        }

        /**
            If we were to write an align right now, how many bits would be required?
            IMPORTANT: Since the number of bits required for alignment depends on where an object is written in the final bit stream, this measurement is conservative.
            @returns Always returns worst case 7 bits.
         */

        int GetAlignBits() const
        {
            return 7;
        }

        /**
            Serialize a safety check to the stream (measure).
            @returns Always returns true. All checking is performed by debug asserts on write.
         */

        bool SerializeCheck()
        {
#if SERIALIZE_SERIALIZE_CHECKS
            SerializeAlign();
            m_bitsWritten += 32;
#endif // #if SERIALIZE_SERIALIZE_CHECKS
            return true;
        }

        /**
            Get number of bits written so far.
            @returns Number of bits written.
         */

        int GetBitsProcessed() const
        {
            return m_bitsWritten;
        }

        /**
            How many bytes have been written so far?
            @returns Number of bytes written.
         */

        int GetBytesProcessed() const
        {
            return ( m_bitsWritten + 7 ) / 8;
        }

    private:

        int m_bitsWritten;              ///< Counts the number of bits written.
    };

    /**
        Serialize integer value (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param value The integer value to serialize in [min,max].
        @param min The minimum value.
        @param max The maximum value.
     */

    #define serialize_int( stream, value, min, max )                    \
        do                                                              \
        {                                                               \
            serialize_assert( min < max );                              \
            int32_t int32_value = 0;                                    \
            if ( Stream::IsWriting )                                    \
            {                                                           \
                serialize_assert( int64_t(value) >= int64_t(min) );     \
                serialize_assert( int64_t(value) <= int64_t(max) );     \
                int32_value = (int32_t) value;                          \
            }                                                           \
            if ( !stream.SerializeInteger( int32_value, min, max ) )    \
            {                                                           \
                return false;                                           \
            }                                                           \
            if ( Stream::IsReading )                                    \
            {                                                           \
                value = int32_value;                                    \
                if ( int64_t(value) < int64_t(min) ||                   \
                     int64_t(value) > int64_t(max) )                    \
                {                                                       \
                    return false;                                       \
                }                                                       \
            }                                                           \
        } while (0)

    /**
        Serialize bits to the stream (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param value The unsigned integer value to serialize.
        @param bits The number of bits to serialize in [1,32].
     */

    #define serialize_bits( stream, value, bits )                       \
        do                                                              \
        {                                                               \
            serialize_assert( bits > 0 );                               \
            serialize_assert( bits <= 64 );                             \
            if ( bits <= 32 )                                           \
            {                                                           \
                uint32_t uint32_value = 0;                              \
                if ( Stream::IsWriting )                                \
                {                                                       \
                    uint32_value = (uint32_t) value;                    \
                }                                                       \
                if ( !stream.SerializeBits( uint32_value, bits ) )      \
                {                                                       \
                    return false;                                       \
                }                                                       \
                if ( Stream::IsReading )                                \
                {                                                       \
                    value = uint32_value;                               \
                }                                                       \
            }                                                           \
            else                                                        \
            {                                                           \
                uint32_t hi = 0, lo = 0;                                \
                if ( Stream::IsWriting )                                \
                {                                                       \
                    lo = uint32_t( uint64_t(value) & 0xFFFFFFFF );      \
                    hi = uint32_t( uint64_t(value) >> 32 );             \
                }                                                       \
                if ( !stream.SerializeBits( lo, 32 ) )                  \
                {                                                       \
                    return false;                                       \
                }                                                       \
                if ( !stream.SerializeBits( hi, bits - 32 ) )           \
                {                                                       \
                    return false;                                       \
                }                                                       \
                if ( Stream::IsReading )                                \
                {                                                       \
                    value = ( uint64_t(hi) << 32 ) | lo;                \
                }                                                       \
            }                                                           \
        } while (0)

    /**
        Serialize a boolean value to the stream (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param value The boolean value to serialize.
     */

    #define serialize_bool( stream, value )                             \
        do                                                              \
        {                                                               \
            uint32_t uint32_bool_value = 0;                             \
            if ( Stream::IsWriting )                                    \
            {                                                           \
                uint32_bool_value = value ? 1 : 0;                      \
            }                                                           \
            serialize_bits( stream, uint32_bool_value, 1 );             \
            if ( Stream::IsReading )                                    \
            {                                                           \
                value = uint32_bool_value ? true : false;               \
            }                                                           \
        } while (0)

    template <typename Stream> bool serialize_float_internal( Stream & stream, float & value )
    {
        uint32_t int_value;
        if ( Stream::IsWriting )
        {
            memcpy( &int_value, &value, 4 );
        }
        bool result = stream.SerializeBits( int_value, 32 );
        if ( Stream::IsReading )
        {
            memcpy( &value, &int_value, 4 );
        }
        return result;
    }

    /**
        Serialize floating point value (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param value The float value to serialize.
     */

    #define serialize_float( stream, value )                                        \
        do                                                                          \
        {                                                                           \
            if ( !serialize::serialize_float_internal( stream, value ) )            \
            {                                                                       \
                return false;                                                       \
            }                                                                       \
        } while (0)

    template <typename Stream> bool serialize_compressed_float_internal(Stream &stream,
                                             float &value,
                                             float min,
                                             float max,
                                             float res)
    {
        const float delta = max - min;

        const float values = delta / res;

        const uint32_t maxIntegerValue = (uint32_t) ceil(values);

        const int bits = bits_required( 0, maxIntegerValue );
        
        uint32_t integerValue = 0;
        
        if ( Stream::IsWriting )
        {
            float normalizedValue = clamp( (value - min) / delta, 0.0f, 1.0f );
            integerValue = (uint32_t) floor( normalizedValue * maxIntegerValue + 0.5f );
        }

        if ( !stream.SerializeBits( integerValue, bits ) )
        {
            return false;
        }
        
        if ( Stream::IsReading )
        {
            const float normalizedValue = integerValue / float(maxIntegerValue);
            value = normalizedValue * delta + min;
        }
        
        return true;
    }

    /**
        Serialize compressed floating point value (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param value The float value to serialize.
     */
    #define serialize_compressed_float(stream, value, min, max, res)                       \
    do                                                                                     \
    {                                                                                      \
        if (!serialize::serialize_compressed_float_internal(stream, value, min, max, res)) \
        {                                                                                  \
            return false;                                                                  \
        }                                                                                  \
    } while (0)

    template <typename Stream> bool serialize_double_internal( Stream & stream, double & value )
    {
        union DoubleInt
        {
            double double_value;
            uint64_t int_value;
        };
        DoubleInt tmp = { 0 };
        if ( Stream::IsWriting )
        {
            tmp.double_value = value;
        }
        serialize_bits( stream, tmp.int_value, 64 );
        if ( Stream::IsReading )
        {
            value = tmp.double_value;
        }
        return true;
    }

    /**
        Serialize double precision floating point value to the stream (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param value The double precision floating point value to serialize.
     */

    #define serialize_double( stream, value )                                       \
        do                                                                          \
        {                                                                           \
            if ( !serialize::serialize_double_internal( stream, value ) )           \
            {                                                                       \
                return false;                                                       \
            }                                                                       \
        } while (0)

    template <typename Stream> bool serialize_bytes_internal( Stream & stream, uint8_t * data, int bytes )
    {
        return stream.SerializeBytes( data, bytes );
    }

    /**
        Serialize an array of bytes to the stream (read/write/measure).
        This is a helper macro to make unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param data Pointer to the data to be serialized.
        @param bytes The number of bytes to serialize.
     */

    #define serialize_bytes( stream, data, bytes )                                  \
        do                                                                          \
        {                                                                           \
            if ( !serialize::serialize_bytes_internal( stream, data, bytes ) )      \
            {                                                                       \
                return false;                                                       \
            }                                                                       \
        } while (0)

    template <typename Stream> bool serialize_string_internal( Stream & stream, char * string, int buffer_size )
    {
        int length = 0;
        if ( Stream::IsWriting )
        {
            length = (int) strlen( string );
            serialize_assert( length < buffer_size );
        }
        serialize_int( stream, length, 0, buffer_size - 1 );
        serialize_bytes( stream, (uint8_t*)string, length );
        if ( Stream::IsReading )
        {
            string[length] = '\0';
        }
        return true;
    }

    /**
        Serialize a string to the stream (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param string The string to serialize write/measure. Pointer to buffer to be filled on read.
        @param buffer_size The size of the string buffer. String with terminating null character must fit into this buffer.
     */

    #define serialize_string( stream, string, buffer_size )                                 \
        do                                                                                  \
        {                                                                                   \
            if ( !serialize::serialize_string_internal( stream, string, buffer_size ) )     \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
        } while (0)

    /**
        Serialize an alignment to the stream (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
     */

    #define serialize_align( stream )                                                       \
        do                                                                                  \
        {                                                                                   \
            if ( !stream.SerializeAlign() )                                                 \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
        } while (0)

    /**
        Serialize an object to the stream (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param object The object to serialize. Must have a serialize method on it.
     */

    #define serialize_object( stream, object )                                              \
        do                                                                                  \
        {                                                                                   \
            if ( !object.Serialize( stream ) )                                              \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
        }                                                                                   \
        while(0)

    template <typename Stream, typename T> bool serialize_int_relative_internal( Stream & stream, T previous, T & current )
    {
        uint32_t difference = 0;
        if ( Stream::IsWriting )
        {
            serialize_assert( previous < current );
            difference = current - previous;
        }

        bool oneBit = false;
        if ( Stream::IsWriting )
        {
            oneBit = difference == 1;
        }
        serialize_bool( stream, oneBit );
        if ( oneBit )
        {
            if ( Stream::IsReading )
            {
                current = previous + 1;
            }
            return true;
        }

        bool twoBits = false;
        if ( Stream::IsWriting )
        {
            twoBits = difference <= 6;
        }
        serialize_bool( stream, twoBits );
        if ( twoBits )
        {
            serialize_int( stream, difference, 2, 6 );
            if ( Stream::IsReading )
            {
                current = previous + difference;
            }
            return true;
        }

        bool fourBits = false;
        if ( Stream::IsWriting )
        {
            fourBits = difference <= 23;
        }
        serialize_bool( stream, fourBits );
        if ( fourBits )
        {
            serialize_int( stream, difference, 7, 23 );
            if ( Stream::IsReading )
            {
                current = previous + difference;
            }
            return true;
        }

        bool eightBits = false;
        if ( Stream::IsWriting )
        {
            eightBits = difference <= 280;
        }
        serialize_bool( stream, eightBits );
        if ( eightBits )
        {
            serialize_int( stream, difference, 24, 280 );
            if ( Stream::IsReading )
            {
                current = previous + difference;
            }
            return true;
        }

        bool twelveBits = false;
        if ( Stream::IsWriting )
        {
            twelveBits = difference <= 4377;
        }
        serialize_bool( stream, twelveBits );
        if ( twelveBits )
        {
            serialize_int( stream, difference, 281, 4377 );
            if ( Stream::IsReading )
            {
                current = previous + difference;
            }
            return true;
        }

        bool sixteenBits = false;
        if ( Stream::IsWriting )
        {
            sixteenBits = difference <= 69914;
        }
        serialize_bool( stream, sixteenBits );
        if ( sixteenBits )
        {
            serialize_int( stream, difference, 4378, 69914 );
            if ( Stream::IsReading )
            {
                current = previous + difference;
            }
            return true;
        }

        uint32_t value = current;
        serialize_bits( stream, value, 32 );
        if ( Stream::IsReading )
        {
            current = value;
        }

        return true;
    }

    /**
        Serialize an integer value relative to another (read/write/measure).
        This is a helper macro to make writing unified serialize functions easier.
        Serialize macros returns false on error so we don't need to use exceptions for error handling on read. This is an important safety measure because packet data comes from the network and may be malicious.
        IMPORTANT: This macro must be called inside a templated serialize function with template \<typename Stream\>. The serialize method must have a bool return value.
        @param stream The stream object. May be a read, write or measure stream.
        @param previous The previous integer value.
        @param current The current integer value.
     */

    #define serialize_int_relative( stream, previous, current )                             \
        do                                                                                  \
        {                                                                                   \
            if ( !serialize::serialize_int_relative_internal( stream, previous, current ) ) \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
        } while (0)

    template <typename Stream> bool serialize_ack_relative_internal( Stream & stream, uint16_t sequence, uint16_t & ack )
    {
        int ack_delta = 0;
        bool ack_in_range = false;
        if ( Stream::IsWriting )
        {
            if ( ack < sequence )
            {
                ack_delta = sequence - ack;
            }
            else
            {
                ack_delta = (int)sequence + 65536 - ack;
            }
            serialize_assert( ack_delta > 0 );
            serialize_assert( uint16_t( sequence - ack_delta ) == ack );
            ack_in_range = ack_delta <= 64;
        }
        serialize_bool( stream, ack_in_range );
        if ( ack_in_range )
        {
            serialize_int( stream, ack_delta, 1, 64 );
            if ( Stream::IsReading )
            {
                ack = sequence - ack_delta;
            }
        }
        else
        {
            serialize_bits( stream, ack, 16 );
        }
        return true;
    }

    // read macros corresponding to each serialize_*. useful when you want separate read and write functions.

    #define read_bits( stream, value, bits )                                                \
    do                                                                                      \
    {                                                                                       \
        serialize_assert( bits > 0 );                                                       \
        serialize_assert( bits <= 32 );                                                     \
        uint32_t uint32_value= 0;                                                           \
        if ( !stream.SerializeBits( uint32_value, bits ) )                                  \
        {                                                                                   \
            return false;                                                                   \
        }                                                                                   \
        value = uint32_value;                                                               \
    } while (0)

    #define read_int( stream, value, min, max )                                             \
        do                                                                                  \
        {                                                                                   \
            serialize_assert( min < max );                                                  \
            int32_t int32_value = 0;                                                        \
            if ( !stream.SerializeInteger( int32_value, min, max ) )                        \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
            value = int32_value;                                                            \
            if ( value < min || value > max )                                               \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
        } while (0)

    #define read_bool( stream, value ) read_bits( stream, value, 1 )

    #define read_float                  serialize_float
    #define read_uint32                 serialize_uint32
    #define read_uint64                 serialize_uint64
    #define read_double                 serialize_double
    #define read_bytes                  serialize_bytes
    #define read_string                 serialize_string
    #define read_align                  serialize_align
    #define read_check                  serialize_check
    #define read_object                 serialize_object
    #define read_int_relative           serialize_int_relative

    // write macros corresponding to each serialize_*. useful when you want separate read and write functions for some reason.

    #define write_bits( stream, value, bits )                                               \
        do                                                                                  \
        {                                                                                   \
            serialize_assert( bits > 0 );                                                   \
            serialize_assert( bits <= 32 );                                                 \
            uint32_t uint32_value = (uint32_t) value;                                       \
            if ( !stream.SerializeBits( uint32_value, bits ) )                              \
            {                                                                               \
                return false;                                                               \
            }                                                                               \
        } while (0)

    #define write_int( stream, value, min, max )                                            \
        do                                                                                  \
        {                                                                                   \
            serialize_assert( min < max );                                                  \
            serialize_assert( value >= min );                                               \
            serialize_assert( value <= max );                                               \
            int32_t int32_value = (int32_t) value;                                          \
            if ( !stream.SerializeInteger( int32_value, min, max ) )                        \
                return false;                                                               \
        } while (0)

    #define write_float                 serialize_float
    #define write_uint32                serialize_uint32
    #define write_uint64                serialize_uint64
    #define write_double                serialize_double
    #define write_bytes                 serialize_bytes
    #define write_string                serialize_string
    #define write_align                 serialize_align
    #define write_object                serialize_object
    #define write_int_relative          serialize_int_relative
}

inline void serialize_copy_string( char * dest, const char * source, size_t dest_size )
{
    serialize_assert( dest );
    serialize_assert( source );
    serialize_assert( dest_size >= 1 );
    memset( dest, 0, dest_size );
    for ( size_t i = 0; i < dest_size - 1; i++ )
    {
        if ( source[i] == '\0' )
            break;
        dest[i] = source[i];
    }
}

#if SERIALIZE_ENABLE_TESTS

#include <time.h>

inline void SerializeCheckHandler( const char * condition,
                                   const char * function,
                                   const char * file,
                                   int line )
{
    printf( "check failed: ( %s ), function %s, file %s, line %d\n", condition, function, file, line );
#ifndef NDEBUG
    #if defined( __GNUC__ )
        __builtin_trap();
    #elif defined( _MSC_VER )
        __debugbreak();
    #endif
#endif
    exit( 1 );
}

#define serialize_check( condition )                                                    \
do                                                                                      \
{                                                                                       \
    if ( !(condition) )                                                                 \
    {                                                                                   \
        SerializeCheckHandler( #condition, __FUNCTION__, __FILE__, __LINE__ );          \
    }                                                                                   \
} while(0)

inline void test_endian()
{
    uint32_t value = 0x11223344;

    const char * bytes = (const char*) &value;

#if SERIALIZE_LITTLE_ENDIAN

    serialize_check( bytes[0] == 0x44 );
    serialize_check( bytes[1] == 0x33 );
    serialize_check( bytes[2] == 0x22 );
    serialize_check( bytes[3] == 0x11 );

#else // #if SERIALIZE_LITTLE_ENDIAN

    serialize_check( bytes[3] == 0x44 );
    serialize_check( bytes[2] == 0x33 );
    serialize_check( bytes[1] == 0x22 );
    serialize_check( bytes[0] == 0x11 );

#endif // #if SERIALIZE_LITTLE_ENDIAN
}

inline void test_bitpacker()
{
    const int BufferSize = 256;

    uint8_t buffer[BufferSize];

    serialize::BitWriter writer( buffer, BufferSize );

    serialize_check( writer.GetData() == buffer );
    serialize_check( writer.GetBitsWritten() == 0 );
    serialize_check( writer.GetBytesWritten() == 0 );
    serialize_check( writer.GetBitsAvailable() == BufferSize * 8 );

    writer.WriteBits( 0, 1 );
    writer.WriteBits( 1, 1 );
    writer.WriteBits( 10, 8 );
    writer.WriteBits( 255, 8 );
    writer.WriteBits( 1000, 10 );
    writer.WriteBits( 50000, 16 );
    writer.WriteBits( 9999999, 32 );
    writer.FlushBits();

    const int bitsWritten = 1 + 1 + 8 + 8 + 10 + 16 + 32;

    serialize_check( writer.GetBytesWritten() == 10 );
    serialize_check( writer.GetBitsWritten() == bitsWritten );
    serialize_check( writer.GetBitsAvailable() == BufferSize * 8 - bitsWritten );

    const int bytesWritten = writer.GetBytesWritten();

    serialize_check( bytesWritten == 10 );

    memset( buffer + bytesWritten, 0, BufferSize - bytesWritten );

    serialize::BitReader reader( buffer, bytesWritten );

    serialize_check( reader.GetBitsRead() == 0 );
    serialize_check( reader.GetBitsRemaining() == bytesWritten * 8 );

    uint32_t a = reader.ReadBits( 1 );
    uint32_t b = reader.ReadBits( 1 );
    uint32_t c = reader.ReadBits( 8 );
    uint32_t d = reader.ReadBits( 8 );
    uint32_t e = reader.ReadBits( 10 );
    uint32_t f = reader.ReadBits( 16 );
    uint32_t g = reader.ReadBits( 32 );

    serialize_check( a == 0 );
    serialize_check( b == 1 );
    serialize_check( c == 10 );
    serialize_check( d == 255 );
    serialize_check( e == 1000 );
    serialize_check( f == 50000 );
    serialize_check( g == 9999999 );

    serialize_check( reader.GetBitsRead() == bitsWritten );
    serialize_check( reader.GetBitsRemaining() == bytesWritten * 8 - bitsWritten );
}

inline void test_bits_required()
{
    serialize_check( serialize::bits_required( 0, 0 ) == 0 );
    serialize_check( serialize::bits_required( 0, 1 ) == 1 );
    serialize_check( serialize::bits_required( 0, 2 ) == 2 );
    serialize_check( serialize::bits_required( 0, 3 ) == 2 );
    serialize_check( serialize::bits_required( 0, 4 ) == 3 );
    serialize_check( serialize::bits_required( 0, 5 ) == 3 );
    serialize_check( serialize::bits_required( 0, 6 ) == 3 );
    serialize_check( serialize::bits_required( 0, 7 ) == 3 );
    serialize_check( serialize::bits_required( 0, 8 ) == 4 );
    serialize_check( serialize::bits_required( 0, 255 ) == 8 );
    serialize_check( serialize::bits_required( 0, 65535 ) == 16 );
    serialize_check( serialize::bits_required( 0, 4294967295 ) == 32 );
}

const int MaxItems = 11;

struct TestData
{
    TestData()
    {
        memset( this, 0, sizeof( TestData ) );
    }

    int a,b,c;
    uint32_t d : 8;
    uint32_t e : 8;
    uint32_t f : 8;
    bool g;
    uint32_t v32;
    uint64_t v64;
    int numItems;
    int items[MaxItems];
    float float_value;
    float compressed_float_value;
    double double_value;
    uint64_t uint64_value;
    int int_relative;
    uint8_t bytes[17];
    char string[256];
};

struct TestContext
{
    int min;
    int max;
};

struct TestObject
{
    TestData data;

    void Init()
    {
        data.a = 1;
        data.b = -2;
        data.c = 150;
        data.d = 55;
        data.e = 255;
        data.f = 127;
        data.g = true;

        data.numItems = MaxItems / 2;
        for ( int i = 0; i < data.numItems; ++i )
            data.items[i] = i + 10;

        data.compressed_float_value = 2.13f;
        data.float_value = 3.1415926f;
        data.double_value = 1 / 3.0;
        data.uint64_value = 0x1234567898765432L;
        data.int_relative = 5;

        for ( int i = 0; i < (int) sizeof( data.bytes ); ++i )
            data.bytes[i] = rand() % 255;

        serialize_copy_string( data.string, "hello world!", sizeof(data.string) - 1 );
    }

    template <typename Stream> bool Serialize( Stream & stream )
    {
        const TestContext & context = *(const TestContext*) stream.GetContext();

        serialize_int( stream, data.a, context.min, context.max );
        serialize_int( stream, data.b, context.min, context.max );

        serialize_int( stream, data.c, -100, 10000 );

        serialize_bits( stream, data.d, 6 );
        serialize_bits( stream, data.e, 8 );
        serialize_bits( stream, data.f, 7 );

        serialize_align( stream );

        serialize_bool( stream, data.g );

        serialize_int( stream, data.numItems, 0, MaxItems - 1 );
        for ( int i = 0; i < data.numItems; ++i )
            serialize_bits( stream, data.items[i], 8 );

        serialize_float( stream, data.float_value );

        serialize_compressed_float( stream, data.compressed_float_value, 0, 10, 0.01 );

        serialize_double( stream, data.double_value );

        serialize_bits( stream, data.uint64_value, 64 );

        serialize_int_relative( stream, data.a, data.int_relative );

        serialize_bytes( stream, data.bytes, sizeof( data.bytes ) );

        serialize_string( stream, data.string, sizeof( data.string ) );

        return true;
    }

    bool operator == ( const TestObject & other ) const
    {
        return memcmp( &data, &other.data, sizeof( TestData ) ) == 0;
    }

    bool operator != ( const TestObject & other ) const
    {
        return ! ( *this == other );
    }
};

inline void test_stream()
{
    const int BufferSize = 1024;

    uint8_t buffer[BufferSize];

    TestContext context;
    context.min = -10;
    context.max = +10;

    serialize::WriteStream writeStream( buffer, BufferSize );

    TestObject writeObject;
    writeObject.Init();
    writeStream.SetContext( &context );
    writeObject.Serialize( writeStream );
    writeStream.Flush();

    const int bytesWritten = writeStream.GetBytesProcessed();

    memset( buffer + bytesWritten, 0, BufferSize - bytesWritten );

    TestObject readObject;
    serialize::ReadStream readStream( buffer, bytesWritten );
    readStream.SetContext( &context );
    readObject.Serialize( readStream );

    serialize_check( readObject == writeObject );
}

#define SERIALIZE_RUN_TEST( test_function )                                 \
    do                                                                      \
    {                                                                       \
        printf( #test_function "\n" );                                      \
        test_function();                                                    \
    }                                                                       \
    while (0)

inline void serialize_test()
{
    // while ( 1 )
    {
        SERIALIZE_RUN_TEST( test_endian );
        SERIALIZE_RUN_TEST( test_bitpacker );
        SERIALIZE_RUN_TEST( test_bits_required );
        SERIALIZE_RUN_TEST( test_stream );
    }
}

#endif // #if SERIALIZE_ENABLE_TESTS

#endif // #ifndef SERIALIZE_H