1  /* memcmp -- compare two memory regions.
       2     This function is in the public domain.  */
       3  
       4  /*
       5  
       6  @deftypefn Supplemental int memcmp (const void *@var{x}, const void *@var{y}, @
       7    size_t @var{count})
       8  
       9  Compares the first @var{count} bytes of two areas of memory.  Returns
      10  zero if they are the same, a value less than zero if @var{x} is
      11  lexically less than @var{y}, or a value greater than zero if @var{x}
      12  is lexically greater than @var{y}.  Note that lexical order is determined
      13  as if comparing unsigned char arrays.
      14  
      15  @end deftypefn
      16  
      17  */
      18  
      19  #include <ansidecl.h>
      20  #include <stddef.h>
      21  
      22  int
      23  memcmp (const void *str1, const void *str2, size_t count)
      24  {
      25    register const unsigned char *s1 = (const unsigned char*)str1;
      26    register const unsigned char *s2 = (const unsigned char*)str2;
      27  
      28    while (count-- > 0)
      29      {
      30        if (*s1++ != *s2++)
      31  	  return s1[-1] < s2[-1] ? -1 : 1;
      32      }
      33    return 0;
      34  }
      35