c_cpp/etc/md5_sha/must_align.c

   1 /*
   2  * must_align - determine if longs must be aligned
   3  *
   4  * @(#) $Revision: 13.1 $
   5  * @(#) $Id: must_align.c,v 13.1 2006/08/14 03:16:33 chongo Exp $
   6  * @(#) $Source: /usr/local/src/cmd/hash/RCS/must_align.c,v $
   7  *
   8  * This file was written by Landon Curt Noll.
   9  *
  10  * This code has been placed in the public domain.  Please do not
  11  * copyright this code.
  12  *
  13  * LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH  REGARD  TO
  14  * THIS  SOFTWARE,  INCLUDING  ALL IMPLIED WARRANTIES OF MER-
  15  * CHANTABILITY AND FITNESS.  IN NO EVENT SHALL  LANDON  CURT
  16  * NOLL  BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
  17  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM  LOSS  OF
  18  * USE,  DATA  OR  PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  19  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR  IN
  20  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  21  *
  22  * chongo (was here) /\oo/\
  23  * http://www.isthe.com/chongo/index.html
  24  *
  25  * Share and enjoy! :-)
  26  */
  27
  28 #include <stdio.h>
  29 #include <signal.h>
  30 #include <stdlib.h>
  31
  32 void buserr(int);               /* catch alignment errors */
  33
  34 /*ARGSUSED*/
  35 int
  36 main(int argc, char *argv[])
  37 {
  38     char byte[2*sizeof(unsigned long)]; /* mis-alignment buffer */
  39     unsigned long *p;   /* mis-alignment pointer */
  40     int i;
  41
  42     /* usage */
  43     if (argc != 1) {
  44         fprintf(stderr, "usage: %s\n", argv[0]);
  45         exit(1);
  46     }
  47
  48 #if !defined(MUST_ALIGN)
  49     /* setup to catch alignment bus errors */
  50     signal(SIGBUS, buserr);
  51     signal(SIGSEGV, buserr);    /* some systems will generate SEGV instead! */
  52
  53     /* mis-align our long fetches */
  54     for (i=0; i < sizeof(long); ++i) {
  55         p = (unsigned long *)(byte+i);
  56         *((volatile unsigned long *) p) = i;
  57         *((volatile unsigned long *) p) += 1;
  58     }
  59
  60     /* if we got here, then we can mis-align longs */
  61     printf("#undef MUST_ALIGN\n");
  62
  63 #else
  64     /* force alignment */
  65     printf("#define MUST_ALIGN\n");
  66 #endif
  67     exit(0);
  68 }
  69
  70
  71 /*
  72  * buserr - catch an alignment error
  73  */
  74 /*ARGSUSED*/
  75 void
  76 buserr(int sig)
  77 {
  78     /* alignment is required */
  79     printf("#define MUST_ALIGN\n");
  80     exit(0);
  81 }