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2 | daniel-mar | 1 | // CRC32 calculates a cyclic redundancy code (CRC), known as CRC-32, using |
2 | // a byte-wise algorithm. |
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3 | // |
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4 | // (C) Copyright 1989, 1995-1996, 1999 Earl F. Glynn, Overland Park, KS. |
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5 | // All Rights Reserved. |
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6 | // |
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7 | // This UNIT was derived from the CRCT FORTRAN 77 program given in |
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8 | // "Byte-wise CRC Calculations" by Aram Perez in IEEE Micro, June 1983, |
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9 | // pp. 40-50. The constants here are for the CRC-32 generator polynomial, |
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10 | // as defined in the Microsoft Systems Journal, March 1995, pp. 107-108 |
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11 | // |
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12 | // This CRC algorithm emphasizes speed at the expense of the 256-element |
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13 | // lookup table. |
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14 | // |
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15 | // Updated for Delphi 4 dynamic arrays and stream I/O. July 1999. |
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16 | |||
17 | UNIT CRC32; |
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18 | |||
19 | INTERFACE |
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20 | |||
21 | USES |
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22 | Windows; // DWORD for D3/D4 compatibility |
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23 | |||
24 | TYPE |
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25 | {$IFDEF VER130} // This is a bit awkward |
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26 | // 8-byte integer |
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27 | TInteger8 = Int64; // Delphi 5 |
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28 | {$ELSE} |
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29 | {$IFDEF VER120} |
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30 | TInteger8 = Int64; // Delphi 4 |
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31 | {$ELSE} |
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32 | TInteger8 = COMP; // Delphi 2 or 3 |
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33 | {$ENDIF} |
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34 | {$ENDIF} |
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35 | |||
36 | PROCEDURE CalcCRC32 (p: pointer; ByteCount: DWORD; VAR CRCvalue: DWORD); |
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37 | |||
38 | PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: DWORD; |
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39 | VAR TotalBytes: TInteger8; |
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40 | VAR error: WORD); |
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41 | |||
42 | IMPLEMENTATION |
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43 | |||
44 | USES |
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45 | {$IFDEF StreamIO} |
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46 | SysUtils, // SysErrorMessage |
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47 | {$ENDIF} |
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48 | Dialogs, // ShowMessage |
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49 | Classes, // TMemoryStream |
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50 | LongFilenameOperations; // added by ViaThinkSoft |
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51 | |||
52 | CONST |
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53 | table: ARRAY[0..255] OF DWORD = |
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54 | ($00000000, $77073096, $EE0E612C, $990951BA, |
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55 | $076DC419, $706AF48F, $E963A535, $9E6495A3, |
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56 | $0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988, |
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57 | $09B64C2B, $7EB17CBD, $E7B82D07, $90BF1D91, |
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58 | $1DB71064, $6AB020F2, $F3B97148, $84BE41DE, |
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59 | $1ADAD47D, $6DDDE4EB, $F4D4B551, $83D385C7, |
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60 | $136C9856, $646BA8C0, $FD62F97A, $8A65C9EC, |
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61 | $14015C4F, $63066CD9, $FA0F3D63, $8D080DF5, |
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62 | $3B6E20C8, $4C69105E, $D56041E4, $A2677172, |
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63 | $3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B, |
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64 | $35B5A8FA, $42B2986C, $DBBBC9D6, $ACBCF940, |
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65 | $32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59, |
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66 | $26D930AC, $51DE003A, $C8D75180, $BFD06116, |
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67 | $21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F, |
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68 | $2802B89E, $5F058808, $C60CD9B2, $B10BE924, |
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69 | $2F6F7C87, $58684C11, $C1611DAB, $B6662D3D, |
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70 | |||
71 | $76DC4190, $01DB7106, $98D220BC, $EFD5102A, |
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72 | $71B18589, $06B6B51F, $9FBFE4A5, $E8B8D433, |
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73 | $7807C9A2, $0F00F934, $9609A88E, $E10E9818, |
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74 | $7F6A0DBB, $086D3D2D, $91646C97, $E6635C01, |
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75 | $6B6B51F4, $1C6C6162, $856530D8, $F262004E, |
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76 | $6C0695ED, $1B01A57B, $8208F4C1, $F50FC457, |
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77 | $65B0D9C6, $12B7E950, $8BBEB8EA, $FCB9887C, |
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78 | $62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65, |
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79 | $4DB26158, $3AB551CE, $A3BC0074, $D4BB30E2, |
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80 | $4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB, |
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81 | $4369E96A, $346ED9FC, $AD678846, $DA60B8D0, |
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82 | $44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9, |
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83 | $5005713C, $270241AA, $BE0B1010, $C90C2086, |
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84 | $5768B525, $206F85B3, $B966D409, $CE61E49F, |
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85 | $5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4, |
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86 | $59B33D17, $2EB40D81, $B7BD5C3B, $C0BA6CAD, |
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87 | |||
88 | $EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A, |
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89 | $EAD54739, $9DD277AF, $04DB2615, $73DC1683, |
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90 | $E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8, |
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91 | $E40ECF0B, $9309FF9D, $0A00AE27, $7D079EB1, |
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92 | $F00F9344, $8708A3D2, $1E01F268, $6906C2FE, |
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93 | $F762575D, $806567CB, $196C3671, $6E6B06E7, |
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94 | $FED41B76, $89D32BE0, $10DA7A5A, $67DD4ACC, |
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95 | $F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5, |
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96 | $D6D6A3E8, $A1D1937E, $38D8C2C4, $4FDFF252, |
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97 | $D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B, |
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98 | $D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60, |
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99 | $DF60EFC3, $A867DF55, $316E8EEF, $4669BE79, |
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100 | $CB61B38C, $BC66831A, $256FD2A0, $5268E236, |
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101 | $CC0C7795, $BB0B4703, $220216B9, $5505262F, |
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102 | $C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04, |
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103 | $C2D7FFA7, $B5D0CF31, $2CD99E8B, $5BDEAE1D, |
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104 | |||
105 | $9B64C2B0, $EC63F226, $756AA39C, $026D930A, |
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106 | $9C0906A9, $EB0E363F, $72076785, $05005713, |
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107 | $95BF4A82, $E2B87A14, $7BB12BAE, $0CB61B38, |
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108 | $92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21, |
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109 | $86D3D2D4, $F1D4E242, $68DDB3F8, $1FDA836E, |
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110 | $81BE16CD, $F6B9265B, $6FB077E1, $18B74777, |
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111 | $88085AE6, $FF0F6A70, $66063BCA, $11010B5C, |
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112 | $8F659EFF, $F862AE69, $616BFFD3, $166CCF45, |
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113 | $A00AE278, $D70DD2EE, $4E048354, $3903B3C2, |
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114 | $A7672661, $D06016F7, $4969474D, $3E6E77DB, |
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115 | $AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0, |
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116 | $A9BCAE53, $DEBB9EC5, $47B2CF7F, $30B5FFE9, |
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117 | $BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6, |
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118 | $BAD03605, $CDD70693, $54DE5729, $23D967BF, |
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119 | $B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94, |
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120 | $B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D); |
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121 | |||
122 | // Use CalcCRC32 as a procedure so CRCValue can be passed in but |
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123 | // also returned. This allows multiple calls to CalcCRC32 for |
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124 | // the "same" CRC-32 calculation. |
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125 | PROCEDURE CalcCRC32 (p: pointer; ByteCount: DWORD; VAR CRCValue: DWORD); |
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126 | // The following is a little cryptic (but executes very quickly). |
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127 | // The algorithm is as follows: |
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128 | // 1. exclusive-or the input byte with the low-order byte of |
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129 | // the CRC register to get an INDEX |
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130 | // 2. shift the CRC register eight bits to the right |
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131 | // 3. exclusive-or the CRC register with the contents of |
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132 | // Table[INDEX] |
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133 | // 4. repeat steps 1 through 3 for all bytes |
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134 | |||
135 | VAR |
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136 | i: DWORD; |
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137 | q: ^BYTE; |
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138 | BEGIN |
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139 | q := p; |
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140 | FOR i := 0 TO ByteCount-1 DO BEGIN |
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141 | CRCvalue := (CRCvalue SHR 8) XOR |
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142 | Table[ q^ XOR (CRCvalue AND $000000FF) ]; |
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143 | INC(q) |
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144 | END |
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145 | END {CalcCRC32}; |
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146 | |||
147 | |||
148 | {$IFDEF StreamIO} // Contemporary method using TMemoryStream |
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149 | |||
150 | // The CRC-32 value calculated here matches the one from the PKZIP program. |
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151 | // Use MemoryStream to read file in binary mode. |
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152 | PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: DWORD; |
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153 | VAR TotalBytes: TInteger8; |
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154 | VAR error: WORD); |
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155 | VAR |
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156 | Stream: TMemoryStream; |
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157 | BEGIN |
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158 | error := 0; |
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159 | CRCValue := $FFFFFFFF; |
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160 | Stream := TMemoryStream.Create; |
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161 | TRY |
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162 | TRY |
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163 | Stream.LoadFromFile(FromName); |
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164 | IF Stream.Size > 0 |
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165 | THEN CalcCRC32 (Stream.Memory, Stream.Size, CRCvalue) |
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166 | EXCEPT |
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167 | ON E: EReadError DO |
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168 | error := 1 |
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169 | END; |
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170 | |||
171 | CRCvalue := NOT CRCvalue |
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172 | FINALLY |
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173 | Stream.Free |
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174 | END; |
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175 | END {CalcFileCRC32}; |
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176 | |||
177 | {$ELSE} // "older" BlockRead method |
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178 | |||
179 | // The CRC-32 value calculated here matches the one from the PKZIP program. |
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180 | // Use BlockRead to read file in binary mode. |
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181 | PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: DWORD; |
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182 | VAR TotalBytes: TInteger8; |
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183 | VAR error: WORD); |
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184 | CONST |
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185 | BufferSize = 32768; |
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186 | |||
187 | TYPE |
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188 | BufferIndex = 0..BufferSize-1; |
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189 | TBuffer = ARRAY[BufferIndex] OF BYTE; |
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190 | pBuffer = ^TBuffer; |
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191 | |||
192 | VAR |
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193 | BytesRead: INTEGER; |
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194 | FromFile : FILE; |
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195 | FromFile2: THandle; |
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196 | IOBuffer : pBuffer; |
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197 | BEGIN |
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198 | New(IOBuffer); |
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199 | TRY |
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200 | FileMode := 0; {Turbo default is 2 for R/W; 0 is for R/O} |
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201 | CRCValue := $FFFFFFFF; |
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202 | if Length(FromName) >= MAX_PATH then |
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203 | begin |
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204 | MyASSIGNFile (FromFile2,FromName); |
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205 | MyRESET (FromFile2); |
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206 | error := GetLastError; |
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207 | end |
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208 | else |
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209 | begin |
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210 | ASSIGN (FromFile,FromName); |
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211 | {$I-} RESET (FromFile,1); {$I+} |
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212 | error := IOResult; |
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213 | end; |
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214 | IF error = 0 |
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215 | THEN BEGIN |
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216 | TotalBytes := 0; |
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217 | |||
218 | REPEAT |
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219 | if Length(FromName) >= MAX_PATH then // [sic!] "greater equal" is correct! The Delphi functions fail if the filename is 260 or greater, but Microsoft says MAX_PATH is the maximum (legal) length! |
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220 | begin |
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221 | MyBlockRead (FromFile2, IOBuffer^, BufferSize, BytesRead); |
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222 | end |
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223 | else |
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224 | begin |
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225 | {$I-} |
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226 | BlockRead (FromFile, IOBuffer^, BufferSize, BytesRead); |
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227 | {$I+} |
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228 | end; |
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229 | error := IOResult; |
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230 | IF (error = 0) AND (BytesRead > 0) |
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231 | THEN BEGIN |
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232 | CalcCRC32 (IOBuffer, BytesRead, CRCvalue); |
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233 | TotalBytes := TotalBytes + BytesRead; // can't use INC with COMP |
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234 | END |
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235 | UNTIL (BytesRead = 0) OR (error > 0); |
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236 | |||
237 | if Length(FromName) >= MAX_PATH then |
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238 | begin |
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239 | MyCLOSEFile (FromFile2) |
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240 | end |
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241 | else |
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242 | begin |
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243 | CLOSE (FromFile) |
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244 | end; |
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245 | END; |
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246 | CRCvalue := NOT CRCvalue |
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247 | FINALLY |
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248 | Dispose(IOBuffer) |
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249 | END |
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250 | END {CalcFileCRC32}; |
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251 | |||
252 | {$ENDIF} |
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253 | |||
254 | END {CRC32}. |
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255 |