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 PR 3846.  */
       6  
       7  /* { dg-do run } */
       8  /* { dg-options "-O2" } */
       9  
      10  extern void abort (void);
      11  extern void exit (int);
      12  
      13  typedef __SIZE_TYPE__ size_t;
      14  extern int memcmp (const void *, const void *, size_t);
      15  
      16  void
      17  duffcpy (char *dst, const char *src, unsigned long size)
      18  {
      19    switch (size & 3)
      20      {
      21      for (;;)
      22        {
      23  	*dst++ = *src++;
      24      case 3:
      25  	*dst++ = *src++;
      26      case 2:
      27  	*dst++ = *src++;
      28      case 1:
      29  	*dst++ = *src++;
      30      case 0:
      31  	if (size <= 3)
      32  	  break;
      33  	size -= 4;
      34        }
      35      }
      36  }
      37  
      38  const char testpat[] = "The quick brown fox jumped over the lazy dog.";
      39  
      40  int
      41  main()
      42  {
      43    char buf[64];
      44  
      45    duffcpy (buf, testpat, sizeof (testpat));
      46    if (memcmp (buf, testpat, sizeof (testpat)) != 0)
      47      abort ();
      48  
      49    exit (0);
      50  }