inline void put_uint32_le(unsigned char *dst, uint32_t n)
{
    *reinterpret_cast<uint32_t *> (dst) = n;
}

inline void put_uint32_le(unsigned char *dst, uint32_t n)
{
    dst[0] = static_cast<unsigned char> (n & 255);
    dst[1] = static_cast<unsigned char> ((n >> 8) & 255);
    dst[2] = static_cast<unsigned char> ((n >> 16) & 255);
    dst[3] = static_cast<unsigned char> (n >> 24);
}

inline void put_uint32_le(unsigned char *dst, uint32_t n)
{
#ifdef WE_HAVE_LITTLE_ENDIAN_PROCESSOR
    *reinterpret_cast<uint32_t *> (dst) = n;
#else
    dst[0] = static_cast<unsigned char> (n & 255);
    dst[1] = static_cast<unsigned char> ((n >> 8) & 255);
    dst[2] = static_cast<unsigned char> ((n >> 16) & 255);
    dst[3] = static_cast<unsigned char> (n >> 24);
#endif
}

union
{
 uint32_t   v;
 uint8_t    c[4];
}value;

#include <string.h>
#include <stdint.h>

inline uint16_t get_uint16_le(const unsigned char *src)
{
    return *reinterpret_cast<const uint16_t *> (src);
}

inline void put_uint32_le(unsigned char *dst, uint_fast32_t n)
{
    memcpy(dst, &n, 4);
//    *reinterpret_cast<uint32_t *> (dst) = n;
}

extern const uint32_t crc32_table[256];

static uint32_t calculate_crc32(const unsigned char *buf, size_t len)
{
    uint32_t crc = 0;

    while (len--)
    {
        crc ^= crc32_table[*(buf++)];
    }

    return crc;
}

void set_crc32(unsigned char *begin)
{
    size_t sz = 3 + get_uint16_le(begin);
    put_uint32_le(begin + sz, calculate_crc32(begin, sz));
}