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1 /* Duff's device is legal C; test to make sure the compiler
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2 doesn't complain about it.
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3
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4 Jason Thorpe <thorpej@wasabisystems.com>
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5 Derived from Tom Duff's original usenet message about the device. */
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6
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7 /* { dg-do run } */
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8 /* { dg-options "-O2" } */
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9
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10 extern void abort (void);
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11 extern void exit (int);
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12
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13 typedef __SIZE_TYPE__ size_t;
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14 extern int memcmp (const void *, const void *, size_t);
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15
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16 void
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17 duffcpy (char *dst, const char *src, unsigned long size)
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18 {
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19 unsigned long n = (size + 7) / 8;
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20
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21 switch (size % 8)
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22 {
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23 case 0: do { *dst++ = *src++;
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24 case 7: *dst++ = *src++;
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25 case 6: *dst++ = *src++;
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26 case 5: *dst++ = *src++;
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27 case 4: *dst++ = *src++;
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28 case 3: *dst++ = *src++;
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29 case 2: *dst++ = *src++;
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30 case 1: *dst++ = *src++;
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31 } while (--n > 0);
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32 }
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33 }
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34
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35 const char testpat[] = "The quick brown fox jumped over the lazy dog.";
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36
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37 int
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38 main()
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39 {
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40 char buf[64];
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41
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42 duffcpy (buf, testpat, sizeof (testpat));
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43 if (memcmp (buf, testpat, sizeof (testpat)) != 0)
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44 abort ();
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45
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46 exit (0);
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47 }
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