gcc/testsuite/gcc.dg/duff-4.c

   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 }