strncmp.c 2.0 KB

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  1. /* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA. */
  15. #include <string.h>
  16. #include "memcopy.h"
  17. /* Compare no more than N characters of S1 and S2,
  18. returning less than, equal to or greater than zero
  19. if S1 is lexicographically less than, equal to or
  20. greater than S2. */
  21. int attribute_hidden __strncmp (const char *s1, const char *s2, size_t n)
  22. {
  23. unsigned reg_char c1 = '\0';
  24. unsigned reg_char c2 = '\0';
  25. if (n >= 4)
  26. {
  27. size_t n4 = n >> 2;
  28. do
  29. {
  30. c1 = (unsigned char) *s1++;
  31. c2 = (unsigned char) *s2++;
  32. if (c1 == '\0' || c1 != c2)
  33. return c1 - c2;
  34. c1 = (unsigned char) *s1++;
  35. c2 = (unsigned char) *s2++;
  36. if (c1 == '\0' || c1 != c2)
  37. return c1 - c2;
  38. c1 = (unsigned char) *s1++;
  39. c2 = (unsigned char) *s2++;
  40. if (c1 == '\0' || c1 != c2)
  41. return c1 - c2;
  42. c1 = (unsigned char) *s1++;
  43. c2 = (unsigned char) *s2++;
  44. if (c1 == '\0' || c1 != c2)
  45. return c1 - c2;
  46. } while (--n4 > 0);
  47. n &= 3;
  48. }
  49. while (n > 0)
  50. {
  51. c1 = (unsigned char) *s1++;
  52. c2 = (unsigned char) *s2++;
  53. if (c1 == '\0' || c1 != c2)
  54. return c1 - c2;
  55. n--;
  56. }
  57. return c1 - c2;
  58. }
  59. strong_alias(__strncmp,strncmp)