libiberty/memcmp.c

   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
   8 Compares the first @var{count} bytes of two areas of memory.  Returns
   9 zero if they are the same, a value less than zero if @var{x} is
  10 lexically less than @var{y}, or a value greater than zero if @var{x}
  11 is lexically greater than @var{y}.  Note that lexical order is determined
  12 as 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
  25 int
  26 DEFUN(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