bn_mp_reduce_setup.c 1011 B

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  1. #include <tommath.h>
  2. #ifdef BN_MP_REDUCE_SETUP_C
  3. /* LibTomMath, multiple-precision integer library -- Tom St Denis
  4. *
  5. * LibTomMath is a library that provides multiple-precision
  6. * integer arithmetic as well as number theoretic functionality.
  7. *
  8. * The library was designed directly after the MPI library by
  9. * Michael Fromberger but has been written from scratch with
  10. * additional optimizations in place.
  11. *
  12. * The library is free for all purposes without any express
  13. * guarantee it works.
  14. *
  15. * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
  16. */
  17. /* pre-calculate the value required for Barrett reduction
  18. * For a given modulus "b" it calulates the value required in "a"
  19. */
  20. int mp_reduce_setup (mp_int * a, mp_int * b)
  21. {
  22. int res;
  23. if ((res = mp_2expt (a, b->used * 2 * DIGIT_BIT)) != MP_OKAY) {
  24. return res;
  25. }
  26. return mp_div (a, b, a, NULL);
  27. }
  28. #endif
  29. /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_setup.c,v $ */
  30. /* $Revision: 1.3 $ */
  31. /* $Date: 2006/03/31 14:18:44 $ */