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
memcmp(const PTR str1,const PTR str2,size_t count)23 memcmp (const PTR str1, const PTR 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
36