62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
# /* Copyright (C) 2002
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# * Housemarque Oy
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# * http://www.housemarque.com
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# *
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# * Distributed under the Boost Software License, Version 1.0. (See
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# * accompanying file LICENSE_1_0.txt or copy at
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# * http://www.boost.org/LICENSE_1_0.txt)
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# */
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#
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# /* Revised by Paul Mensonides (2002) */
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#
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# /* See http://www.boost.org for most recent version. */
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#
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# /* This example uses the preprocessor library to implement a generalized
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# * macro for implementing Duff's Device.
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# *
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# * This example was inspired by an original generalized macro for
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# * for implementing Duff's Device written by Joerg Walter.
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# */
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#
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# include <assert.h>
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#
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# include <boost/preprocessor/repetition/repeat.hpp>
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# include <boost/preprocessor/tuple/elem.hpp>
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#
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# /* Expands to a Duff's Device. */
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# define DUFFS_DEVICE(UNROLLING_FACTOR, COUNTER_TYPE, N, STATEMENT) \
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do { \
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COUNTER_TYPE duffs_device_initial_cnt = (N); \
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if (duffs_device_initial_cnt > 0) { \
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COUNTER_TYPE duffs_device_running_cnt = (duffs_device_initial_cnt + (UNROLLING_FACTOR - 1)) / UNROLLING_FACTOR; \
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switch (duffs_device_initial_cnt % UNROLLING_FACTOR) { \
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do { \
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BOOST_PP_REPEAT(UNROLLING_FACTOR, DUFFS_DEVICE_C, (UNROLLING_FACTOR, { STATEMENT })) \
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} while (--duffs_device_running_cnt); \
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} \
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} \
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} while (0) \
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/**/
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#
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# define DUFFS_DEVICE_C(Z, I, UNROLLING_FACTOR_STATEMENT) \
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case (I ? BOOST_PP_TUPLE_ELEM(2, 0, UNROLLING_FACTOR_STATEMENT) - I : 0): \
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BOOST_PP_TUPLE_ELEM(2, 1, UNROLLING_FACTOR_STATEMENT); \
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/**/
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#
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# ifndef UNROLLING_FACTOR
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# define UNROLLING_FACTOR 16
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# endif
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#
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# ifndef N
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# define N 1000
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# endif
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int main(void) {
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int i = 0;
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DUFFS_DEVICE(UNROLLING_FACTOR, int, 0, ++i;);
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assert(i == 0);
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DUFFS_DEVICE(UNROLLING_FACTOR, int, N, ++i;);
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assert(i == N);
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return 0;
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}
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