* \brief TEA encryption function.
* This function encrypts <EM>v</EM> with <EM>k</EM> and returns the
* encrypted data in <EM>v</EM>.
* \brief TEA encryption function.
* This function encrypts <EM>v</EM> with <EM>k</EM> and returns the
* encrypted data in <EM>v</EM>.