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1 // Range.cc -*- C++ -*- |
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2 /* |
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4 Copyright (C) 1992, 1993, 1994 John W. Eaton |
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5 |
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6 This file is part of Octave. |
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7 |
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8 Octave is free software; you can redistribute it and/or modify it |
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9 under the terms of the GNU General Public License as published by the |
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10 Free Software Foundation; either version 2, or (at your option) any |
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11 later version. |
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12 |
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13 Octave is distributed in the hope that it will be useful, but WITHOUT |
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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16 for more details. |
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17 |
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18 You should have received a copy of the GNU General Public License |
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19 along with Octave; see the file COPYING. If not, write to the Free |
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20 Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. |
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21 |
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22 */ |
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23 |
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24 #ifdef HAVE_CONFIG_H |
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25 #include "config.h" |
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26 #endif |
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27 |
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28 #if defined (__GNUG__) |
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29 #pragma implementation |
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30 #endif |
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31 |
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32 #include <iostream.h> |
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33 #include <limits.h> |
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34 |
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35 #include "Range.h" |
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36 |
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37 // NOTE: max and min only return useful values if nelem > 0. |
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38 |
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39 double |
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40 Range::min (void) const |
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41 { |
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42 double retval = 0.0; |
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43 if (rng_nelem > 0) |
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44 { |
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45 if (rng_inc > 0) |
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46 retval = rng_base; |
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47 else |
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48 retval = rng_base + (rng_nelem - 1) * rng_inc; |
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49 } |
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50 return retval; |
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51 } |
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52 |
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53 double |
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54 Range::max (void) const |
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55 { |
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56 double retval = 0.0; |
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57 if (rng_nelem > 0) |
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58 { |
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59 if (rng_inc > 0) |
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60 retval = rng_base + (rng_nelem - 1) * rng_inc; |
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61 else |
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62 retval = rng_base; |
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63 } |
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64 return retval; |
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65 } |
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66 |
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67 void |
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68 Range::sort (void) |
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69 { |
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70 if (rng_base > rng_limit && rng_inc < 0.0) |
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71 { |
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72 double tmp = rng_base; |
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73 rng_base = min (); |
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74 rng_limit = tmp; |
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75 rng_inc = -rng_inc; |
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76 } |
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77 } |
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78 |
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79 void |
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80 Range::print_range (void) |
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81 { |
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82 cerr << "Range: rng_base = " << rng_base |
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83 << " rng_limit " << rng_limit |
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84 << " rng_inc " << rng_inc |
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85 << " rng_nelem " << rng_nelem << "\n"; |
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86 } |
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87 |
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88 ostream& |
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89 operator << (ostream& os, const Range& a) |
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90 { |
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91 double b = a.base (); |
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92 double increment = a.inc (); |
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93 int num_elem = a.nelem (); |
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94 |
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95 for (int i = 0; i < num_elem; i++) |
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96 os << b + i * increment << " "; |
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97 |
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98 os << "\n"; |
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99 |
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100 return os; |
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101 } |
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102 |
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103 istream& |
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104 operator >> (istream& is, Range& a) |
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105 { |
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106 is >> a.rng_base; |
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107 if (is) |
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108 { |
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109 is >> a.rng_limit; |
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110 if (is) |
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111 { |
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112 is >> a.rng_inc; |
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113 a.rng_nelem = a.nelem_internal (); |
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114 } |
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115 } |
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116 |
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117 return is; |
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118 } |
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119 |
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120 int |
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121 Range::nelem_internal (void) const |
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122 { |
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123 // Find an approximate number of intervals, then do the best we can to |
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124 // find the number of intervals that we would get if we had done |
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125 // something like |
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126 // |
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127 // nelem = 0; |
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128 // while (base + nelem * inc <= limit) |
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129 // nelem++; |
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130 // |
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131 // (for limit > base && inc > 0) |
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132 // |
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133 // The number of elements in the range is one greater than the number |
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134 // of intervals. |
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135 |
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136 // We can't have more than INT_MAX elements in the range. |
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137 |
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138 double d_n_intervals = (rng_limit - rng_base) / rng_inc; |
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139 int max_intervals = INT_MAX - 1; |
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140 double d_max_val = (double) max_intervals; |
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141 |
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142 if (d_n_intervals > d_max_val) |
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143 return -1; |
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144 |
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145 int n_intervals = (d_n_intervals > 0) |
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146 ? ((int) (d_n_intervals + 0.5)) |
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147 : ((int) (d_n_intervals - 0.5)); |
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148 |
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149 if (rng_limit > rng_base && rng_inc > 0) |
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150 { |
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151 // Our approximation may have been too big. |
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152 |
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153 while (rng_base + n_intervals * rng_inc > rng_limit && n_intervals > 0) |
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154 n_intervals--; |
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155 |
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156 // Now that we are close, get the actual number. Try to avoid |
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157 // problems with extended precision registers. |
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158 |
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159 for (;;) |
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160 { |
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161 volatile double tmp_inc = (n_intervals + 1) * rng_inc; |
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162 volatile double tmp_val = rng_base + tmp_inc; |
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163 if (tmp_val <= rng_limit && n_intervals < max_intervals) |
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164 n_intervals++; |
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165 else |
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166 break; |
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167 } |
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168 } |
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169 else if (rng_limit < rng_base && rng_inc < 0) |
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170 { |
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171 // Our approximation may have been too big. |
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172 |
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173 while (rng_base + n_intervals * rng_inc < rng_limit && n_intervals > 0) |
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174 n_intervals--; |
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175 |
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176 // Now that we are close, get the actual number. Try to avoid |
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177 // problems with extended precision registers. |
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178 |
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179 for (;;) |
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180 { |
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181 volatile double tmp_inc = (n_intervals + 1) * rng_inc; |
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182 volatile double tmp_val = rng_base + tmp_inc; |
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183 if (tmp_val >= rng_limit && n_intervals < max_intervals) |
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184 n_intervals++; |
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185 else |
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186 break; |
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187 } |
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188 } |
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189 else if (rng_limit == rng_base) |
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190 n_intervals = 0; |
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191 else |
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192 n_intervals = -1; |
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193 |
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194 return (n_intervals >= max_intervals) ? -1 : n_intervals + 1; |
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195 } |
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196 |
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197 /* |
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198 ;;; Local Variables: *** |
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199 ;;; mode: C++ *** |
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200 ;;; page-delimiter: "^/\\*" *** |
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201 ;;; End: *** |
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202 */ |
