1 | /*************************************************************************** |
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2 | * blitz/array/reduce.cc Array reductions. |
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3 | * |
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4 | * $Id$ |
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5 | * |
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6 | * Copyright (C) 1997-2011 Todd Veldhuizen <tveldhui@acm.org> |
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7 | * |
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8 | * This file is a part of Blitz. |
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9 | * |
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10 | * Blitz is free software: you can redistribute it and/or modify |
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11 | * it under the terms of the GNU Lesser General Public License |
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12 | * as published by the Free Software Foundation, either version 3 |
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13 | * of the License, or (at your option) any later version. |
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14 | * |
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15 | * Blitz is distributed in the hope that it will be useful, |
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16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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18 | * GNU Lesser General Public License for more details. |
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19 | * |
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20 | * You should have received a copy of the GNU Lesser General Public |
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21 | * License along with Blitz. If not, see <http://www.gnu.org/licenses/>. |
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22 | * |
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23 | * Suggestions: blitz-devel@lists.sourceforge.net |
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24 | * Bugs: blitz-support@lists.sourceforge.net |
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25 | * |
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26 | * For more information, please see the Blitz++ Home Page: |
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27 | * https://sourceforge.net/projects/blitz/ |
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28 | * |
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29 | ****************************************************************************/ |
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30 | #ifndef BZ_ARRAYREDUCE_H |
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31 | #error <blitz/array/reduce.cc> must be included via <blitz/array/reduce.h> |
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32 | #endif |
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33 | |
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34 | BZ_NAMESPACE(blitz) |
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35 | |
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36 | template<typename T_expr, typename T_reduction> |
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37 | _bz_typename T_reduction::T_resulttype |
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38 | _bz_ArrayExprFullReduce(T_expr expr, T_reduction reduction) |
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39 | { |
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40 | #ifdef BZ_TAU_PROFILING |
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41 | // Tau profiling code. Provide Tau with a pretty-printed version of |
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42 | // the expression. |
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43 | static BZ_STD_SCOPE(string) exprDescription; |
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44 | if (!exprDescription.length()) // faked static initializer |
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45 | { |
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46 | exprDescription = T_reduction::name(); |
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47 | exprDescription += "("; |
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48 | prettyPrintFormat format(true); // Terse mode on |
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49 | expr.prettyPrint(exprDescription, format); |
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50 | exprDescription += ")"; |
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51 | } |
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52 | TAU_PROFILE(" ", exprDescription, TAU_BLITZ); |
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53 | #endif // BZ_TAU_PROFILING |
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54 | |
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55 | return _bz_reduceWithIndexTraversal(expr, reduction); |
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56 | |
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57 | #ifdef BZ_NOT_IMPLEMENTED_FLAG |
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58 | if ((T_expr::numIndexPlaceholders > 0) || (T_reduction::needIndex)) |
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59 | { |
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60 | // The expression involves index placeholders, so have to |
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61 | // use index traversal rather than stack traversal. |
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62 | return reduceWithIndexTraversal(expr, reduction); |
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63 | } |
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64 | else { |
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65 | // Use a stack traversal |
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66 | return reduceWithStackTraversal(expr, reduction); |
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67 | } |
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68 | #endif |
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69 | } |
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70 | |
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71 | template <typename T_index> struct _bz_IndexingVariant; |
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72 | |
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73 | template <> |
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74 | struct _bz_IndexingVariant<int> { |
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75 | template <int N> |
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76 | static int index(const TinyVector<int,N>& ind,const int i) { |
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77 | return ind[i]; |
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78 | } |
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79 | }; |
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80 | |
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81 | template <int N> |
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82 | struct _bz_IndexingVariant<TinyVector<int,N> > { |
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83 | static const TinyVector<int,N>& index(const TinyVector<int,N>& ind,const int) { |
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84 | return ind; |
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85 | } |
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86 | }; |
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87 | |
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88 | template<typename T_index, typename T_expr, typename T_reduction> |
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89 | _bz_typename T_reduction::T_resulttype |
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90 | _bz_reduceWithIndexTraversalGeneric(T_expr expr, T_reduction reduction) |
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91 | { |
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92 | // This is optimized assuming C-style arrays. |
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93 | |
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94 | const int rank = T_expr::rank_; |
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95 | |
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96 | TinyVector<int,T_expr::rank_> index, first, last; |
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97 | |
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98 | unsigned long count = 1; |
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99 | |
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100 | for (int i=0; i < rank; ++i) { |
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101 | first(i) = expr.lbound(i); |
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102 | last(i) = expr.ubound(i) + 1; |
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103 | index(i) = first(i); |
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104 | count *= last(i) - first(i); |
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105 | } |
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106 | |
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107 | const int maxRank = rank - 1; |
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108 | const int lastlbound = expr.lbound(maxRank); |
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109 | const int lastubound = expr.ubound(maxRank); |
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110 | |
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111 | const int lastIndex = lastubound + 1; |
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112 | |
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113 | typedef _bz_IndexingVariant<T_index> adapter; |
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114 | |
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115 | _bz_ReduceReset<T_reduction::needIndex,T_reduction::needInit> reset; |
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116 | reset(reduction,first,expr); |
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117 | |
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118 | while(true) { |
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119 | for (index[maxRank]=lastlbound;index[maxRank]<lastIndex;++index[maxRank]) |
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120 | if (!reduction(expr(index),adapter::index(index,maxRank))) |
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121 | return reduction.result(count); |
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122 | |
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123 | int j = rank-2; |
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124 | for (;j>=0;--j) { |
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125 | index(j+1) = first(j+1); |
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126 | ++index(j); |
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127 | if (index(j) < last(j)) |
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128 | break; |
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129 | } |
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130 | |
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131 | if (j<0) |
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132 | return reduction.result(count); |
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133 | } |
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134 | } |
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135 | |
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136 | template<typename T_expr, typename T_reduction> |
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137 | _bz_typename T_reduction::T_resulttype |
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138 | _bz_reduceWithIndexTraversal(T_expr expr, T_reduction reduction) |
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139 | { |
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140 | return _bz_reduceWithIndexTraversalGeneric<int>(expr,reduction); |
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141 | } |
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142 | |
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143 | // This version is for reductions that require a vector of index positions. |
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144 | |
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145 | template<typename T_expr, typename T_reduction> |
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146 | _bz_typename T_reduction::T_resulttype |
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147 | _bz_reduceWithIndexVectorTraversal(T_expr expr, T_reduction reduction) |
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148 | { |
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149 | // We are doing minIndex/maxIndex, so initialize with lower bound |
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150 | return _bz_reduceWithIndexTraversalGeneric<TinyVector<int,T_expr::rank_> >(expr,reduction); |
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151 | } |
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152 | |
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153 | BZ_NAMESPACE_END |
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154 | |
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