mpih-cmp.c 1.3 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /* mpihelp-sub.c - MPI helper functions
  3. * Copyright (C) 1994, 1996 Free Software Foundation, Inc.
  4. * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
  5. *
  6. * This file is part of GnuPG.
  7. *
  8. * Note: This code is heavily based on the GNU MP Library.
  9. * Actually it's the same code with only minor changes in the
  10. * way the data is stored; this is to support the abstraction
  11. * of an optional secure memory allocation which may be used
  12. * to avoid revealing of sensitive data due to paging etc.
  13. * The GNU MP Library itself is published under the LGPL;
  14. * however I decided to publish this code under the plain GPL.
  15. */
  16. #include "mpi-internal.h"
  17. /****************
  18. * Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE.
  19. * There are no restrictions on the relative sizes of
  20. * the two arguments.
  21. * Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2.
  22. */
  23. int mpihelp_cmp(mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size)
  24. {
  25. mpi_size_t i;
  26. mpi_limb_t op1_word, op2_word;
  27. for (i = size - 1; i >= 0; i--) {
  28. op1_word = op1_ptr[i];
  29. op2_word = op2_ptr[i];
  30. if (op1_word != op2_word)
  31. goto diff;
  32. }
  33. return 0;
  34. diff:
  35. /* This can *not* be simplified to
  36. * op2_word - op2_word
  37. * since that expression might give signed overflow. */
  38. return (op1_word > op2_word) ? 1 : -1;
  39. }