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
cksum(const unsigned char * src,unsigned long size)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
main()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 }
61