text: # ===================================================================
  #
  # Copyright (c) 2014, Legrandin <helderijs@gmail.com>
  # All rights reserved.
  #
  # 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.
  #
  # 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.
  # ===================================================================
  
  from Crypto.Util._raw_api import (load_pycryptodome_raw_lib, c_size_t,
                                    create_string_buffer, get_raw_buffer,
                                    c_uint8_ptr)
  
  _raw_strxor = load_pycryptodome_raw_lib("Crypto.Util._strxor",
                      """
                      void strxor(const uint8_t *in1,
                                  const uint8_t *in2,
                                  uint8_t *out, size_t len);
                      void strxor_c(const uint8_t *in,
                                    uint8_t c,
                                    uint8_t *out,
                                    size_t len);
                      """)
  
  
  def strxor(term1, term2):
      """XOR of two byte strings.
      They must have equal length.
  
      Return:
          A new byte string, :data:`term1` xored with :data:`term2`.
      """
  
      if len(term1) != len(term2):
          raise ValueError("Only byte strings of equal length can be xored")
      
      result = create_string_buffer(len(term1))
      _raw_strxor.strxor(c_uint8_ptr(term1),
                         c_uint8_ptr(term2),
                         result,
                         c_size_t(len(term1)))
      return get_raw_buffer(result)
  
  
  def strxor_c(term, c):
      """XOR of a byte string with a repeated sequence of characters.
  
      Return:
          A new byte string, :data:`term` with all its bytes xored with :data:`c`.
      """
  
      if not 0 <= c < 256:
          raise ValueError("c must be in range(256)")
      result = create_string_buffer(len(term))
      _raw_strxor.strxor_c(c_uint8_ptr(term), c, result, c_size_t(len(term)))
      return get_raw_buffer(result)
  
  def _strxor_direct(term1, term2, result):
      """Very fast XOR - check conditions!"""
      _raw_strxor.strxor(term1, term2, result, c_size_t(len(term1)))
  
  