strncmp.c 2.1 KB

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  1. /* $OpenBSD: strncmp.c,v 1.9 2015/08/31 02:53:57 guenther Exp $ */
  2. /*
  3. * Copyright (c) 1989 The Regents of the University of California.
  4. * All rights reserved.
  5. *
  6. * Redistribution and use in source and binary forms, with or without
  7. * modification, are permitted provided that the following conditions
  8. * are met:
  9. * 1. Redistributions of source code must retain the above copyright
  10. * notice, this list of conditions and the following disclaimer.
  11. * 2. Redistributions in binary form must reproduce the above copyright
  12. * notice, this list of conditions and the following disclaimer in the
  13. * documentation and/or other materials provided with the distribution.
  14. * 3. Neither the name of the University nor the names of its contributors
  15. * may be used to endorse or promote products derived from this software
  16. * without specific prior written permission.
  17. *
  18. * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21. * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28. * SUCH DAMAGE.
  29. */
  30. #include <string.h>
  31. #ifdef _TLIBC_USE_INTEL_FAST_STRING_
  32. extern int _intel_fast_strncmp(const char *, const char *, size_t);
  33. #endif
  34. int
  35. strncmp(const char *s1, const char *s2, size_t n)
  36. {
  37. #ifdef _TLIBC_USE_INTEL_FAST_STRING_
  38. return _intel_fast_strncmp(s1, s2, n);
  39. #else
  40. if (n == 0)
  41. return (0);
  42. do {
  43. if (*s1 != *s2++)
  44. return (*(unsigned char *)s1 - *(unsigned char *)--s2);
  45. if (*s1++ == 0)
  46. break;
  47. } while (--n != 0);
  48. return (0);
  49. #endif
  50. }