1  /* Duff's device is legal C; test to make sure the compiler
       2     doesn't complain about it.
       3  
       4     Roger Sayle <roger@eyesopen.com>
       5     Derived from duff-2.c.  */
       6  
       7  /* { dg-do run } */
       8  /* { dg-options "-O2" } */
       9  
      10  extern void abort (void);
      11  extern void exit (int);
      12  
      13  #if __INT_MAX__ >= 2147483647
      14  /* At least 32-bit integers. */
      15  typedef int type32;
      16  #else
      17  typedef long type32;
      18  #endif
      19  
      20  type32
      21  cksum (const unsigned char *src, unsigned long size)
      22  {
      23    type32 ck = 0;
      24  
      25    switch (size & 3)
      26      {
      27      do
      28        {
      29      case 0:
      30  	ck ^= (type32)*src++ << 24;
      31  	--size;
      32      case 3:
      33  	ck ^= (type32)*src++ << 16;
      34  	--size;
      35      case 2:
      36  	ck ^= (type32)*src++ << 8;
      37  	--size;
      38      case 1:
      39  	ck ^= (type32)*src++;
      40  	--size;
      41        }
      42      while (size > 0);
      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  }