forked from boostorg/preprocessor
64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
/* Copyright (C) 2002
|
|
* Housemarque Oy
|
|
* http://www.housemarque.com
|
|
*
|
|
* Permission to copy, use, modify, sell and distribute this software is
|
|
* granted provided this copyright notice appears in all copies. This
|
|
* software is provided "as is" without express or implied warranty, and
|
|
* with no claim as to its suitability for any purpose.
|
|
*
|
|
* See http://www.boost.org for most recent version.
|
|
*/
|
|
|
|
/* This example uses the preprocessor library to implement a generalized
|
|
* macro for implementing a Duff's Device.
|
|
*
|
|
* This example was inspired by an original generalized macro for
|
|
* implementing Duff's Device written by Joerg Walter.
|
|
*/
|
|
|
|
#include <boost/preprocessor/repeat.hpp>
|
|
#include <boost/preprocessor/tuple/elem.hpp>
|
|
#include <assert.h>
|
|
|
|
/* 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(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;
|
|
}
|