forked from boostorg/preprocessor
62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
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/* 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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* Permission to copy, use, modify, sell and distribute this software is
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* granted provided this copyright notice appears in all copies. This
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* software is provided "as is" without express or implied warranty, and
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* with no claim as to its suitability for any purpose.
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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 a 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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* implementing Duff's Device written by Joerg Walter.
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*/
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#include <boost/preprocessor/repeat.hpp>
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#include <boost/preprocessor/tuple/elem.hpp>
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#include <assert.h>
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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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{\
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COUNTER_TYPE\
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duffs_device_initial_cnt = (N),\
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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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{\
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do\
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{\
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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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} while (0)
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#define DUFFS_DEVICE_C(I,UNROLLING_FACTOR_STATEMENT)\
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case (I?BOOST_PP_TUPLE_ELEM(2,0,UNROLLING_FACTOR_STATEMENT)-I:0): BOOST_PP_TUPLE_ELEM(2,1,UNROLLING_FACTOR_STATEMENT);
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#ifndef UNROLLING_FACTOR
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#define UNROLLING_FACTOR 16
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#endif
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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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{
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int 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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