1 | package Math::BigInt::CalcEmu;
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2 |
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3 | use 5.005;
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4 | use strict;
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5 | # use warnings; # dont use warnings for older Perls
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6 | use vars qw/$VERSION/;
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7 |
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8 | $VERSION = '0.05';
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9 |
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10 | package Math::BigInt;
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11 |
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12 | # See SYNOPSIS below.
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13 |
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14 | my $CALC_EMU;
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15 |
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16 | BEGIN
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17 | {
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18 | $CALC_EMU = Math::BigInt->config()->{'lib'};
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19 | # register us with MBI to get notified of future lib changes
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20 | Math::BigInt::_register_callback( __PACKAGE__, sub { $CALC_EMU = $_[0]; } );
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21 | }
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22 |
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23 | sub __emu_band
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24 | {
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25 | my ($self,$x,$y,$sx,$sy,@r) = @_;
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26 |
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27 | return $x->bzero(@r) if $y->is_zero() || $x->is_zero();
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28 |
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29 | my $sign = 0; # sign of result
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30 | $sign = 1 if $sx == -1 && $sy == -1;
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31 |
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32 | my ($bx,$by);
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33 |
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34 | if ($sx == -1) # if x is negative
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35 | {
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36 | # two's complement: inc and flip all "bits" in $bx
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37 | $bx = $x->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
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38 | $bx =~ s/-?0x//;
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39 | $bx =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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40 | }
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41 | else
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42 | {
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43 | $bx = $x->as_hex(); # get binary representation
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44 | $bx =~ s/-?0x//;
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45 | $bx =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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46 | }
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47 | if ($sy == -1) # if y is negative
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48 | {
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49 | # two's complement: inc and flip all "bits" in $by
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50 | $by = $y->copy()->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
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51 | $by =~ s/-?0x//;
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52 | $by =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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53 | }
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54 | else
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55 | {
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56 | $by = $y->as_hex(); # get binary representation
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57 | $by =~ s/-?0x//;
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58 | $by =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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59 | }
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60 | # now we have bit-strings from X and Y, reverse them for padding
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61 | $bx = reverse $bx;
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62 | $by = reverse $by;
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63 |
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64 | # padd the shorter string
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65 | my $xx = "\x00"; $xx = "\x0f" if $sx == -1;
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66 | my $yy = "\x00"; $yy = "\x0f" if $sy == -1;
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67 | my $diff = CORE::length($bx) - CORE::length($by);
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68 | if ($diff > 0)
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69 | {
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70 | # if $yy eq "\x00", we can cut $bx, otherwise we need to padd $by
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71 | $by .= $yy x $diff;
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72 | }
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73 | elsif ($diff < 0)
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74 | {
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75 | # if $xx eq "\x00", we can cut $by, otherwise we need to padd $bx
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76 | $bx .= $xx x abs($diff);
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77 | }
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78 |
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79 | # and the strings together
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80 | my $r = $bx & $by;
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81 |
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82 | # and reverse the result again
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83 | $bx = reverse $r;
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84 |
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85 | # One of $x or $y was negative, so need to flip bits in the result.
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86 | # In both cases (one or two of them negative, or both positive) we need
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87 | # to get the characters back.
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88 | if ($sign == 1)
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89 | {
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90 | $bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/0123456789abcdef/;
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91 | }
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92 | else
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93 | {
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94 | $bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/fedcba9876543210/;
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95 | }
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96 |
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97 | # leading zeros will be stripped by _from_hex()
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98 | $bx = '0x' . $bx;
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99 | $x->{value} = $CALC_EMU->_from_hex( $bx );
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100 |
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101 | # calculate sign of result
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102 | $x->{sign} = '+';
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103 | $x->{sign} = '-' if $sign == 1 && !$x->is_zero();
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104 |
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105 | $x->bdec() if $sign == 1;
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106 |
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107 | $x->round(@r);
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108 | }
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109 |
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110 | sub __emu_bior
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111 | {
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112 | my ($self,$x,$y,$sx,$sy,@r) = @_;
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113 |
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114 | return $x->round(@r) if $y->is_zero();
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115 |
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116 | my $sign = 0; # sign of result
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117 | $sign = 1 if ($sx == -1) || ($sy == -1);
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118 |
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119 | my ($bx,$by);
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120 |
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121 | if ($sx == -1) # if x is negative
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122 | {
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123 | # two's complement: inc and flip all "bits" in $bx
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124 | $bx = $x->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
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125 | $bx =~ s/-?0x//;
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126 | $bx =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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127 | }
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128 | else
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129 | {
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130 | $bx = $x->as_hex(); # get binary representation
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131 | $bx =~ s/-?0x//;
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132 | $bx =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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133 | }
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134 | if ($sy == -1) # if y is negative
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135 | {
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136 | # two's complement: inc and flip all "bits" in $by
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137 | $by = $y->copy()->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
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138 | $by =~ s/-?0x//;
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139 | $by =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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140 | }
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141 | else
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142 | {
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143 | $by = $y->as_hex(); # get binary representation
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144 | $by =~ s/-?0x//;
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145 | $by =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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146 | }
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147 | # now we have bit-strings from X and Y, reverse them for padding
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148 | $bx = reverse $bx;
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149 | $by = reverse $by;
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150 |
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151 | # padd the shorter string
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152 | my $xx = "\x00"; $xx = "\x0f" if $sx == -1;
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153 | my $yy = "\x00"; $yy = "\x0f" if $sy == -1;
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154 | my $diff = CORE::length($bx) - CORE::length($by);
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155 | if ($diff > 0)
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156 | {
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157 | $by .= $yy x $diff;
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158 | }
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159 | elsif ($diff < 0)
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160 | {
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161 | $bx .= $xx x abs($diff);
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162 | }
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163 |
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164 | # or the strings together
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165 | my $r = $bx | $by;
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166 |
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167 | # and reverse the result again
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168 | $bx = reverse $r;
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169 |
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170 | # one of $x or $y was negative, so need to flip bits in the result
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171 | # in both cases (one or two of them negative, or both positive) we need
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172 | # to get the characters back.
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173 | if ($sign == 1)
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174 | {
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175 | $bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/0123456789abcdef/;
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176 | }
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177 | else
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178 | {
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179 | $bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/fedcba9876543210/;
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180 | }
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181 |
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182 | # leading zeros will be stripped by _from_hex()
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183 | $bx = '0x' . $bx;
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184 | $x->{value} = $CALC_EMU->_from_hex( $bx );
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185 |
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186 | # calculate sign of result
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187 | $x->{sign} = '+';
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188 | $x->{sign} = '-' if $sign == 1 && !$x->is_zero();
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189 |
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190 | # if one of X or Y was negative, we need to decrement result
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191 | $x->bdec() if $sign == 1;
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192 |
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193 | $x->round(@r);
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194 | }
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195 |
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196 | sub __emu_bxor
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197 | {
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198 | my ($self,$x,$y,$sx,$sy,@r) = @_;
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199 |
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200 | return $x->round(@r) if $y->is_zero();
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201 |
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202 | my $sign = 0; # sign of result
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203 | $sign = 1 if $x->{sign} ne $y->{sign};
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204 |
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205 | my ($bx,$by);
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206 |
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207 | if ($sx == -1) # if x is negative
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208 | {
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209 | # two's complement: inc and flip all "bits" in $bx
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210 | $bx = $x->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
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211 | $bx =~ s/-?0x//;
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212 | $bx =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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213 | }
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214 | else
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215 | {
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216 | $bx = $x->as_hex(); # get binary representation
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217 | $bx =~ s/-?0x//;
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218 | $bx =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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219 | }
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220 | if ($sy == -1) # if y is negative
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221 | {
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222 | # two's complement: inc and flip all "bits" in $by
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223 | $by = $y->copy()->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
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224 | $by =~ s/-?0x//;
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225 | $by =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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226 | }
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227 | else
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228 | {
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229 | $by = $y->as_hex(); # get binary representation
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230 | $by =~ s/-?0x//;
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231 | $by =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
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232 | }
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233 | # now we have bit-strings from X and Y, reverse them for padding
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234 | $bx = reverse $bx;
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235 | $by = reverse $by;
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236 |
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237 | # padd the shorter string
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238 | my $xx = "\x00"; $xx = "\x0f" if $sx == -1;
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239 | my $yy = "\x00"; $yy = "\x0f" if $sy == -1;
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240 | my $diff = CORE::length($bx) - CORE::length($by);
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241 | if ($diff > 0)
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242 | {
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243 | $by .= $yy x $diff;
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244 | }
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245 | elsif ($diff < 0)
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246 | {
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247 | $bx .= $xx x abs($diff);
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248 | }
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249 |
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250 | # xor the strings together
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251 | my $r = $bx ^ $by;
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252 |
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253 | # and reverse the result again
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254 | $bx = reverse $r;
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255 |
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256 | # one of $x or $y was negative, so need to flip bits in the result
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257 | # in both cases (one or two of them negative, or both positive) we need
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258 | # to get the characters back.
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259 | if ($sign == 1)
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260 | {
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261 | $bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/0123456789abcdef/;
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262 | }
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263 | else
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264 | {
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265 | $bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/fedcba9876543210/;
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266 | }
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267 |
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268 | # leading zeros will be stripped by _from_hex()
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269 | $bx = '0x' . $bx;
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270 | $x->{value} = $CALC_EMU->_from_hex( $bx );
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271 |
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272 | # calculate sign of result
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273 | $x->{sign} = '+';
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274 | $x->{sign} = '-' if $sx != $sy && !$x->is_zero();
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275 |
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276 | $x->bdec() if $sign == 1;
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277 |
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278 | $x->round(@r);
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279 | }
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280 |
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281 | ##############################################################################
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282 | ##############################################################################
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283 |
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284 | 1;
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285 | __END__
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286 |
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287 | =head1 NAME
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288 |
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289 | Math::BigInt::CalcEmu - Emulate low-level math with BigInt code
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290 |
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291 | =head1 SYNOPSIS
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292 |
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293 | use Math::BigInt::CalcEmu;
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294 |
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295 | =head1 DESCRIPTION
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296 |
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297 | Contains routines that emulate low-level math functions in BigInt, e.g.
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298 | optional routines the low-level math package does not provide on it's own.
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299 |
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300 | Will be loaded on demand and called automatically by BigInt.
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301 |
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302 | Stuff here is really low-priority to optimize, since it is far better to
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303 | implement the operation in the low-level math libary directly, possible even
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304 | using a call to the native lib.
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305 |
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306 | =head1 METHODS
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307 |
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308 | =head2 __emu_bxor
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309 |
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310 | =head2 __emu_band
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311 |
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312 | =head2 __emu_bior
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313 |
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314 | =head1 LICENSE
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315 |
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316 | This program is free software; you may redistribute it and/or modify it under
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317 | the same terms as Perl itself.
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318 |
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319 | =head1 AUTHORS
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320 |
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321 | (c) Tels http://bloodgate.com 2003, 2004 - based on BigInt code by
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322 | Tels from 2001-2003.
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323 |
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324 | =head1 SEE ALSO
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325 |
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326 | L<Math::BigInt>, L<Math::BigFloat>, L<Math::BigInt::BitVect>,
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327 | L<Math::BigInt::GMP> and L<Math::BigInt::Pari>.
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328 |
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329 | =cut
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