gcc/testsuite/gcc.dg/duff-2.c

   1 /* Duff's device is legal C; test to make sure the compiler
   2    doesn't complain about it.
   3
   4    Jason Thorpe <thorpej@wasabisystems.com>
   5    Derived from the BSD Telnet Kerberos 4 checksum routine.
   6    See also PR 5230.  */
   7
   8 /* { dg-do run } */
   9 /* { dg-options "-O2" } */
  10
  11 extern void abort (void);
  12 extern void exit (int);
  13
  14 #if __INT_MAX__ >= 2147483647
  15 /* At least 32-bit integers. */
  16 typedef int type32;
  17 #else
  18 typedef long type32;
  19 #endif
  20
  21 type32
  22 cksum (const unsigned char *src, unsigned long size)
  23 {
  24   type32 ck = 0;
  25
  26   switch (size & 3)
  27     {
  28     while (size > 0)
  29       {
  30     case 0:
  31         ck ^= (type32)*src++ << 24;
  32         --size;
  33     case 3:
  34         ck ^= (type32)*src++ << 16;
  35         --size;
  36     case 2:
  37         ck ^= (type32)*src++ << 8;
  38         --size;
  39     case 1:
  40         ck ^= (type32)*src++;
  41         --size;
  42       }
  43     }
  44
  45   return ck;
  46 }
  47
  48 const char testpat[] = "The quick brown fox jumped over the lazy dog.";
  49
  50 int
  51 main()
  52 {
  53   type32 ck;
  54
  55   ck = cksum ((const unsigned char *) testpat, sizeof (testpat));
  56   if (ck != 925902908)
  57     abort ();
  58
  59   exit (0);
  60 }