1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
# /* Copyright (C) 2002
# * Housemarque Oy
# * http://www.housemarque.com
# *
# * Distributed under the Boost Software License, Version 1.0. (See
# * accompanying file LICENSE_1_0.txt or copy at
# * http://www.boost.org/LICENSE_1_0.txt)
# */
#
# /* Revised by Paul Mensonides (2002) */
#
# /* See http://www.boost.org for most recent version. */
#
# /* This example uses the preprocessor library to implement a generalized
# * macro for implementing Duff's Device.
# *
# * This example was inspired by an original generalized macro for
# * for implementing Duff's Device written by Joerg Walter.
# */
#
# include <assert.h>
#
# include <boost/preprocessor/repetition/repeat.hpp>
# include <boost/preprocessor/tuple/elem.hpp>
#
# /* Expands to a Duff's Device. */
# define DUFFS_DEVICE(UNROLLING_FACTOR, COUNTER_TYPE, N, STATEMENT) \
do { \
COUNTER_TYPE duffs_device_initial_cnt = (N); \
if (duffs_device_initial_cnt > 0) { \
COUNTER_TYPE duffs_device_running_cnt = (duffs_device_initial_cnt + (UNROLLING_FACTOR - 1)) / UNROLLING_FACTOR; \
switch (duffs_device_initial_cnt % UNROLLING_FACTOR) { \
do { \
BOOST_PP_REPEAT(UNROLLING_FACTOR, DUFFS_DEVICE_C, (UNROLLING_FACTOR, { STATEMENT })) \
} while (--duffs_device_running_cnt); \
} \
} \
} while (0) \
/**/
#
# define DUFFS_DEVICE_C(Z, I, UNROLLING_FACTOR_STATEMENT) \
case (I ? BOOST_PP_TUPLE_ELEM(2, 0, UNROLLING_FACTOR_STATEMENT) - I : 0): \
BOOST_PP_TUPLE_ELEM(2, 1, UNROLLING_FACTOR_STATEMENT); \
/**/
#
# ifndef UNROLLING_FACTOR
# define UNROLLING_FACTOR 16
# endif
#
# ifndef N
# define N 1000
# endif
int main(void) {
int i = 0;
DUFFS_DEVICE(UNROLLING_FACTOR, int, 0, ++i;);
assert(i == 0);
DUFFS_DEVICE(UNROLLING_FACTOR, int, N, ++i;);
assert(i == N);
return 0;
}
|
