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748 | daniel-mar | 1 | unit WEID; |
2 | |||
3 | (* |
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4 | * WEID<=>OID Converter for TurboPascal |
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5 | * (c) Webfan.de, ViaThinkSoft |
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6 | * Revision 2022-02-19 |
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7 | *) |
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8 | |||
9 | (* |
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10 | What is a WEID? |
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11 | A WEID (WEhowski IDentifier) is an alternative representation of an |
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12 | OID (Object IDentifier) defined by Till Wehowski. |
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13 | In OIDs, arcs are in decimal base 10. In WEIDs, the arcs are in base 36. |
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14 | Also, each WEID has a check digit at the end (called WeLohn Check Digit). |
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15 | |||
16 | Changes in the December 2021 definition by Daniel Marschall: |
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17 | - There are several classes of WEIDs which have different OID bases: |
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18 | "Class C" WEID: weid:EXAMPLE-3 (base .1.3.6.1.4.1.37553.8.) |
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19 | oid:1.3.6.1.4.1.37553.8.32488192274 |
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20 | "Class B" WEID: weid:pen:SX0-7PR-6 (base .1.3.6.1.4.1.) |
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21 | oid:1.3.6.1.4.1.37476.9999 |
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22 | "Class A" WEID: weid:root:2-RR-2 (base .) |
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23 | oid:2.999 |
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24 | - The namespace (weid:, weid:pen:, weid:root:) is now case insensitive. |
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25 | - Padding with '0' characters is valid (e.g. weid:000EXAMPLE-3) |
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26 | The paddings do not count into the WeLuhn check-digit. |
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27 | *) |
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28 | |||
29 | interface |
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30 | |||
31 | (* |
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32 | Translates a weid to an oid |
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33 | "weid:EXAMPLE-3" becomes "1.3.6.1.4.1.37553.8.32488192274" |
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34 | If it failed (e.g. wrong namespace, wrong checksum, etc.) then false is returned. |
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35 | If the weid ends with '?', then it will be replaced with the checksum, |
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36 | e.g. weid:EXAMPLE-? becomes weid:EXAMPLE-3 |
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37 | *) |
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38 | function WeidToOid(var weid: string): string; |
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39 | |||
40 | (* |
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41 | Converts an OID to WEID |
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42 | "1.3.6.1.4.1.37553.8.32488192274" becomes "weid:EXAMPLE-3" |
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43 | *) |
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44 | function OidToWeid(oid: string): string; |
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45 | |||
46 | implementation |
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47 | |||
48 | uses |
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49 | VtsFuncs; |
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50 | |||
51 | function weLuhnGetCheckDigit(s: string): integer; |
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52 | var |
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53 | p: integer; |
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54 | wrkstr: string; |
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55 | c: Char; |
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56 | i: Integer; |
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57 | sum: integer; |
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58 | nbdigits: Integer; |
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59 | parity: Integer; |
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60 | n: Integer; |
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61 | digit: Integer; |
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62 | begin |
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63 | (* Padding zeros don't count to the check digit (December 2021) *) |
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64 | s := '-' + s + '-'; |
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65 | while Pos('-0', s) > 0 do |
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66 | begin |
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67 | s := StringReplace(s, '-0-', #1); |
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68 | s := StringReplace(s, '-0', '-'); |
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69 | end; |
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70 | s := StringReplace(s, #1, '-0-'); |
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71 | s := Copy(s, 2, Length(s)-2); |
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72 | |||
73 | (* remove separators of the WEID string *) |
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74 | wrkstr := StringReplace(s, '-', ''); |
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75 | |||
76 | (* Replace 'a' with '10', 'b' with '11', etc. *) |
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77 | for c := 'A' to 'Z' do |
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78 | begin |
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79 | wrkstr := StringReplace(wrkstr, c, IntToStr(Ord(c)-Ord('A')+10)); |
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80 | end; |
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81 | |||
749 | daniel-mar | 82 | (* At the end, wrkstr should only contain digits! Verify it! *) |
748 | daniel-mar | 83 | for i := 1 to Length(wrkstr) do |
84 | begin |
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85 | if not (wrkstr[i] in ['0'..'9']) then |
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86 | begin |
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87 | weLuhnGetCheckDigit := -1; |
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88 | exit; |
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89 | end; |
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90 | end; |
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91 | |||
92 | (* Now do the standard Luhn algorithm *) |
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93 | nbdigits := Length(wrkstr); |
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94 | parity := nbdigits and 1; (* mod 2 *) |
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95 | sum := 0; |
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96 | for n := nbdigits-1 downto 0 do |
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97 | begin |
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98 | digit := StrToInt(wrkstr[n+1]); |
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99 | if (n and 1) <> parity then digit := digit * 2; |
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100 | if digit > 9 then digit := digit - 9; |
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101 | sum := sum + digit; |
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102 | end; |
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103 | |||
104 | if sum mod 10 = 0 then |
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105 | weLuhnGetCheckDigit := 0 |
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106 | else |
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107 | weLuhnGetCheckDigit := 10 - (sum mod 10); |
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108 | end; |
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109 | |||
110 | function WeidToOid(var weid: string): string; |
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111 | var |
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112 | base: string; |
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113 | namespace: string; |
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114 | p: integer; |
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115 | rest: string; |
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116 | actual_checksum: string; |
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117 | expected_checksum: integer; |
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118 | complete: string; |
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119 | oidstr: string; |
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120 | arc: string; |
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121 | begin |
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122 | p := LastCharPos(weid,':'); |
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123 | namespace := Copy(weid, 1, p); |
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124 | rest := Copy(weid, p+1, Length(weid)-p); |
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125 | |||
126 | namespace := LowerCase(namespace); (* namespace is case insensitive *) |
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127 | if namespace = 'weid:' then |
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128 | begin |
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129 | (* Class C *) |
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130 | base := '1-3-6-1-4-1-SZ5-8'; |
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131 | end |
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132 | else if namespace = 'weid:pen:' then |
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133 | begin |
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134 | (* Class B *) |
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135 | base := '1-3-6-1-4-1'; |
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136 | end |
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137 | else if namespace = 'weid:root:' then |
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138 | begin |
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139 | (* Class A *) |
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140 | base := ''; |
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141 | end |
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142 | else |
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143 | begin |
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144 | (* Wrong namespace *) |
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145 | WeidToOid := ''; |
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146 | Exit; |
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147 | end; |
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148 | |||
149 | weid := rest; |
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150 | |||
151 | if base <> '' then |
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152 | complete := base + '-' + weid |
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153 | else |
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154 | complete := weid; |
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155 | p := LastCharPos(complete, '-'); |
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156 | actual_checksum := Copy(complete, p+1, 1); |
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157 | complete := Copy(complete, 1, p-1); |
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158 | expected_checksum := weLuhnGetCheckDigit(complete); |
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159 | if (actual_checksum <> '?') then |
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160 | begin |
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161 | if actual_checksum <> IntToStr(expected_checksum) then |
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162 | begin |
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163 | WeidToOid := ''; (* wrong checksum *) |
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164 | Exit; |
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165 | end; |
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166 | end |
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167 | else |
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168 | begin |
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169 | (* If checksum is '?', it will be replaced by the actual checksum, *) |
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170 | (* e.g. weid:EXAMPLE-? becomes weid:EXAMPLE-3 *) |
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171 | weid := StringReplace(weid, '?', IntToStr(expected_checksum)); |
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172 | end; |
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173 | |||
174 | oidstr := ''; |
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175 | while true do |
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176 | begin |
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177 | p := Pos('-', complete); |
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178 | if p = 0 then p := Length(complete)+1; |
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179 | arc := Copy(complete, 1, p-1); |
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180 | Delete(complete, 1, p); |
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181 | oidstr := oidstr + base_convert_bigint(arc, 36, 10) + '.'; |
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182 | if complete = '' then break; |
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183 | end; |
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184 | oidstr := Copy(oidstr, 1, Length(oidstr)-1); |
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185 | |||
186 | weid := namespace + weid; (* add namespace again *) |
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187 | |||
188 | WeidToOid := oidstr; |
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189 | end; |
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190 | |||
191 | function OidToWeid(oid: string): string; |
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192 | var |
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193 | is_class_a: boolean; |
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194 | is_class_b: boolean; |
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195 | is_class_c: boolean; |
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196 | weidstr: string; |
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197 | checksum: string; |
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198 | namespace: string; |
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199 | p: Integer; |
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200 | cd: Integer; |
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201 | res: string; |
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202 | begin |
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203 | if Copy(oid,1,1) = '.' then |
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204 | Delete(oid,1,1); (* remove leading dot *) |
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205 | |||
206 | if oid <> '' then |
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207 | begin |
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208 | weidstr := ''; |
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209 | while true do |
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210 | begin |
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211 | p := Pos('.', oid); |
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212 | if p = 1 then |
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213 | begin |
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214 | Delete(oid, 1, 1); |
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215 | end |
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216 | else if p > 0 then |
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217 | begin |
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218 | weidstr := weidstr + base_convert_bigint(Copy(oid, 1, p-1),10,36) + '-'; |
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219 | Delete(oid, 1, p); |
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220 | end |
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221 | else |
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222 | begin |
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223 | weidstr := weidstr + base_convert_bigint(oid,10,36) + '-'; |
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224 | break; |
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225 | end; |
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226 | end; |
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227 | weidstr := Copy(weidstr, 1, Length(weidstr)-1); |
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228 | end |
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229 | else |
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230 | begin |
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231 | weidstr := ''; |
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232 | end; |
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233 | |||
234 | is_class_c := (Pos('1-3-6-1-4-1-SZ5-8-', weidstr) = 1) or |
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235 | (weidstr = '1-3-6-1-4-1-SZ5-8'); |
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236 | is_class_b := ((Pos('1-3-6-1-4-1-', weidstr) = 1) or |
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237 | (weidstr = '1-3-6-1-4-1')) |
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238 | and not is_class_c; |
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239 | is_class_a := not is_class_b and not is_class_c; |
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240 | |||
241 | cd := weLuhnGetCheckDigit(weidstr); |
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242 | if cd < 0 then |
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243 | begin |
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244 | OidToWeid := weidstr; |
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245 | exit; |
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246 | end; |
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247 | checksum := IntToStr(cd); |
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248 | |||
249 | if is_class_c then |
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250 | begin |
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251 | Delete(weidstr, 1, Length('1-3-6-1-4-1-SZ5-8-')); |
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252 | namespace := 'weid:'; |
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253 | end |
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254 | else if is_class_b then |
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255 | begin |
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256 | Delete(weidstr, 1, Length('1-3-6-1-4-1-')); |
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257 | namespace := 'weid:pen:'; |
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258 | end |
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259 | else if is_class_a then |
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260 | begin |
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261 | (* weidstr stays *) |
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262 | namespace := 'weid:root:'; |
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263 | end |
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264 | else |
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265 | begin |
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266 | (* should not happen *) |
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267 | OidToWeid := ''; |
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268 | Exit; |
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269 | end; |
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270 | |||
271 | res := namespace; |
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272 | if weidstr = '' then |
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273 | res := res + checksum |
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274 | else |
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275 | res := res + weidstr + '-' + checksum; |
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276 | OidToWeid := res; |
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277 | end; |
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278 | |||
279 | end. |