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C/C++ Source or Header  |  1994-04-15  |  6.2 KB  |  185 lines
  1. /* Area: F-BBS Standards ──────────────────────────────────────────────────────
  2.  * Msg#: 11                                           Date: 14 Apr 94  13:12:22
  3.  * From: Ted Spaulding                                Read: Yes    Replied: No 
  4.  *   To: SERGEY POLAK                                 Mark:                     
  5.  * Subj: RE: CRC CALULATIONS FOR E
  6.  * ────────────────────────────────────────────────────────────────────────────
  7.  *
  8.  * CRC32.C      (C)opyright Ted R. Spaulding & Asylum Associates
  9.  *              Written 21 Aug, 1993
  10.  *
  11.  * This file contains the two routines needed to perform 32 bit CRC
  12.  * calculations.  One is used for calculating CRCs on a block, the
  13.  * other one is used on a character by character basis.
  14.  *
  15.  * Contains: CRC32Block()
  16.  *           CRC32Char()
  17.  *
  18.  * ****NOTE*****
  19.  * - Inorder to PROPERLY Calculate the CRC32 Value, Your Seed value
  20.  *   MUST be -1, and your end result MUST be Byte XOR'ed...
  21.  * - EXAMPLE:
  22.  
  23.   void main(void)
  24.   {
  25.     SHORT FHand, bytes;
  26.     LONG totbytes, crc;
  27.     char buffer[1024];
  28.  
  29.     FHand=open("SOMEFILE.ZIP", O_BINARY_RDONLY);
  30.     totbytes=filelength(FHand);
  31. *Set "Seed" Value To -1
  32.     crc=0xFFFFFFFFL;
  33.     do {
  34.       bytes=read(FHand, buffer, 1024);
  35.       crc=CRC32Block(bytes, crc, buffer);
  36.       totbytes-=bytes;
  37.     } while(totbytes>0);
  38.     close(FHand);
  39. *Bytewise XOR the result for the CRC Value
  40.     crc^=0xFFFFFFFFL;
  41.     printf("\r\nCRC Value=%08lx\r\n\n", crc);
  42.   }
  43.  
  44.  *
  45.  *
  46.  *
  47.  */
  48.  
  49. /*
  50.  * This is the lookup table used when performing the CRC calculation.
  51.  */
  52.  
  53. /*  Function Prototypes */
  54.  
  55. ULONG CRC32Block(USHORT count, ULONG crc, char *buffer);
  56. ULONG CRC32Char(ULONG crc, unsigned char c);
  57. void build_table_32(USHORT table[]);
  58.  
  59. /*  I Declare these because I compile BOTH 16 and 32 Bit Code -
  60.     Thus, this is why I NEVER use an "int" */
  61.  
  62. #define LONG long
  63. #define ULONG unsigned long
  64. #define SHORT short
  65. #define USHORT unsigned short
  66.  
  67. #define CRC32_POLYNOMIAL     0xEDB88320L
  68.  
  69. static ULONG ccitt_32[256] =
  70. {
  71. 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL,
  72. 0x076dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L,
  73. 0x0edb8832L, 0x79dcb8a4L, 0xe0d5e91eL, 0x97d2d988L,
  74. 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, 0x90bf1d91L,
  75. 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
  76. 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L,
  77. 0x136c9856L, 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL,
  78. 0x14015c4fL, 0x63066cd9L, 0xfa0f3d63L, 0x8d080df5L,
  79. 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, 0xa2677172L,
  80. 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
  81. 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L,
  82. 0x32d86ce3L, 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L,
  83. 0x26d930acL, 0x51de003aL, 0xc8d75180L, 0xbfd06116L,
  84. 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 0xb8bda50fL,
  85. 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
  86. 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL,
  87. 0x76dc4190L, 0x01db7106L, 0x98d220bcL, 0xefd5102aL,
  88. 0x71b18589L, 0x06b6b51fL, 0x9fbfe4a5L, 0xe8b8d433L,
  89. 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, 0xe10e9818L,
  90. 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
  91. 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL,
  92. 0x6c0695edL, 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L,
  93. 0x65b0d9c6L, 0x12b7e950L, 0x8bbeb8eaL, 0xfcb9887cL,
  94. 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, 0xfbd44c65L,
  95. 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
  96. 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL,
  97. 0x4369e96aL, 0x346ed9fcL, 0xad678846L, 0xda60b8d0L,
  98. 0x44042d73L, 0x33031de5L, 0xaa0a4c5fL, 0xdd0d7cc9L,
  99. 0x5005713cL, 0x270241aaL, 0xbe0b1010L, 0xc90c2086L,
  100. 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
  101. 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L,
  102. 0x59b33d17L, 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL,
  103. 0xedb88320L, 0x9abfb3b6L, 0x03b6e20cL, 0x74b1d29aL,
  104. 0xead54739L, 0x9dd277afL, 0x04db2615L, 0x73dc1683L,
  105. 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
  106. 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L,
  107. 0xf00f9344L, 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL,
  108. 0xf762575dL, 0x806567cbL, 0x196c3671L, 0x6e6b06e7L,
  109. 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, 0x67dd4accL,
  110. 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
  111. 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L,
  112. 0xd1bb67f1L, 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL,
  113. 0xd80d2bdaL, 0xaf0a1b4cL, 0x36034af6L, 0x41047a60L,
  114. 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 0x4669be79L,
  115. 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
  116. 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL,
  117. 0xc5ba3bbeL, 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L,
  118. 0xc2d7ffa7L, 0xb5d0cf31L, 0x2cd99e8bL, 0x5bdeae1dL,
  119. 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, 0x026d930aL,
  120. 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
  121. 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L,
  122. 0x92d28e9bL, 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L,
  123. 0x86d3d2d4L, 0xf1d4e242L, 0x68ddb3f8L, 0x1fda836eL,
  124. 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, 0x18b74777L,
  125. 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
  126. 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L,
  127. 0xa00ae278L, 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L,
  128. 0xa7672661L, 0xd06016f7L, 0x4969474dL, 0x3e6e77dbL,
  129. 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 0x37d83bf0L,
  130. 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
  131. 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L,
  132. 0xbad03605L, 0xcdd70693L, 0x54de5729L, 0x23d967bfL,
  133. 0xb3667a2eL, 0xc4614ab8L, 0x5d681b02L, 0x2a6f2b94L,
  134. 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, 0x2d02ef8dL
  135. };
  136.  
  137. ULONG CRC32Block(USHORT count, ULONG crc, void *buffer)
  138. {
  139.     unsigned char *p=buffer;
  140.   ULONG temp1;
  141.   ULONG temp2;
  142.  
  143.     while(count--!=0) {
  144.         temp1=(crc>>8) & 0x00FFFFFFL;
  145.         temp2=ccitt_32[((int)crc^*p++) & 0xff];
  146.         crc=temp1^temp2;
  147.     }
  148.     return(crc);
  149. }
  150.  
  151. ULONG CRC32Char(ULONG crc, unsigned char c )
  152. {
  153.   ULONG temp1;
  154.   ULONG temp2;
  155.  
  156.     temp1=(crc>>8) & 0x00FFFFFFL;
  157.     temp2=ccitt_32[((int)crc^c) & 0xff];
  158.     return(temp1^temp2);
  159. }
  160.  
  161. /* This is the function that I origionally used to build the above
  162.    table.  I include it here for Completeness ONLY */
  163.  
  164. void build_table_32(unsigned int table[])
  165. {
  166.   SHORT i, j;
  167.   ULONG crc;
  168.  
  169.     for(i=0; i<=255; i++) {
  170.         crc = i;
  171.         for(j=8; j>0; j--) {
  172.             if(crc&1)
  173.                 crc=(crc>>1)^CRC32_POLYNOMIAL;
  174.             else
  175.                 crc>>=1;
  176.         }
  177.     table[i]=crc;
  178.     }
  179. }
  180.  
  181.  
  182. -!- CelToScn v1.08   S/N:00001
  183.  ! Origin: Asylum Associates - (716) 872-5887  [Webster, NY] (1:2613/171.0)
  184.  
  185.