libiberty: Fix build with GCC < 7

[thirdparty/gcc.git] / libiberty / strncmp.c

/* strncmp -- compare two strings, stop after n bytes.
   This function is in the public domain.  */

/*

@deftypefn Supplemental int strncmp (const char *@var{s1}, @
  const char *@var{s2}, size_t @var{n})

Compares the first @var{n} bytes of two strings, returning a value as
@code{strcmp}.

@end deftypefn

*/

#include <ansidecl.h>
#include <stddef.h>

int
strncmp(const char *s1, const char *s2, register size_t n)
{
  register unsigned char u1, u2;

  while (n-- > 0)
    {
      u1 = (unsigned char) *s1++;
      u2 = (unsigned char) *s2++;
      if (u1 != u2)
	return u1 - u2;
      if (u1 == '\0')
	return 0;
    }
  return 0;
}