unroll.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// unroll.h: Rcpp R/C++ interface class library -- loop unrolling macro 
//
// Copyright (C) 2010 - 2011 Dirk Eddelbuettel and Romain Francois
//
// This file is part of Rcpp.
//
// Rcpp is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// Rcpp is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.

#ifndef Rcpp__macros_unroll_h
#define Rcpp__macros_unroll_h
   
#define RCPP_LOOP_UNROLL(TARGET,SOURCE)           \
int __trip_count = n >> 2 ;                       \
int i = 0 ;                                       \
for ( ; __trip_count > 0 ; --__trip_count) {      \
        TARGET[i] = SOURCE[i] ; i++ ;                 \
        TARGET[i] = SOURCE[i] ; i++ ;                 \
        TARGET[i] = SOURCE[i] ; i++ ;                 \
        TARGET[i] = SOURCE[i] ; i++ ;                 \
}                                                 \
switch (n - i){                                   \
  case 3:                                         \
      TARGET[i] = SOURCE[i] ; i++ ;               \
  case 2:                                         \
      TARGET[i] = SOURCE[i] ; i++ ;               \
  case 1:                                         \
      TARGET[i] = SOURCE[i] ; i++ ;               \
  case 0:                                         \
  default:                                        \
      {}                                          \
}

#define RCPP_LOOP_UNROLL_LHSFUN(TARGET,FUN,SOURCE)           \
int __trip_count = n >> 2 ;                       \
int i = 0 ;                                       \
for ( ; __trip_count > 0 ; --__trip_count) {      \
        TARGET[FUN(i)] = SOURCE[i] ; i++ ;                 \
        TARGET[FUN(i)] = SOURCE[i] ; i++ ;                 \
        TARGET[FUN(i)] = SOURCE[i] ; i++ ;                 \
        TARGET[FUN(i)] = SOURCE[i] ; i++ ;                 \
}                                                 \
switch (n - i){                                   \
  case 3:                                         \
      TARGET[FUN(i)] = SOURCE[i] ; i++ ;               \
  case 2:                                         \
      TARGET[FUN(i)] = SOURCE[i] ; i++ ;               \
  case 1:                                         \
      TARGET[FUN(i)] = SOURCE[i] ; i++ ;               \
  case 0:                                         \
  default:                                        \
      {}                                          \
}

#endif