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 Tom Duff's original usenet message about the device. */
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
duffcpy(char * dst,const char * src,unsigned long size)17 duffcpy (char *dst, const char *src, unsigned long size)
18 {
19 unsigned long n = (size + 7) / 8;
20
21 switch (size % 8)
22 {
23 case 0: do { *dst++ = *src++;
24 case 7: *dst++ = *src++;
25 case 6: *dst++ = *src++;
26 case 5: *dst++ = *src++;
27 case 4: *dst++ = *src++;
28 case 3: *dst++ = *src++;
29 case 2: *dst++ = *src++;
30 case 1: *dst++ = *src++;
31 } while (--n > 0);
32 }
33 }
34
35 const char testpat[] = "The quick brown fox jumped over the lazy dog.";
36
37 int
main()38 main()
39 {
40 char buf[64];
41
42 duffcpy (buf, testpat, sizeof (testpat));
43 if (memcmp (buf, testpat, sizeof (testpat)) != 0)
44 abort ();
45
46 exit (0);
47 }
48