memcmp.c revision 89857 
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}, size_t @var{count})
7
8Compares the first @var{count} bytes of two areas of memory.  Returns
9zero if they are the same, a value less than zero if @var{x} is
10lexically less than @var{y}, or a value greater than zero if @var{x}
11is lexically greater than @var{y}.  Note that lexical order is determined
12as if comparing unsigned char arrays.
13
14@end deftypefn
15
16*/
17
18#include <ansidecl.h>
19#ifdef __STDC__
20#include <stddef.h>
21#else
22#define size_t unsigned long
23#endif
24
25int
26DEFUN(memcmp, (str1, str2, count),
27      const PTR str1 AND const PTR str2 AND size_t count)
28{
29  register const unsigned char *s1 = (const unsigned char*)str1;
30  register const unsigned char *s2 = (const unsigned char*)str2;
31
32  while (count-- > 0)
33    {
34      if (*s1++ != *s2++)
35	  return s1[-1] < s2[-1] ? -1 : 1;
36    }
37  return 0;
38}
39
40