CRC-32 code

 BBS: Inland Empire Archive
Date: 01-03-93 (01:24)             Number: 209
From: ERIC B. FORD                 Refer#: NONE
  To: VICTOR YIU                    Recvd: NO  
Subj: CRC-32 code                    Conf: (2) Quik_Bas

 > Do any of you have some BASIC code to do CRC-32s?  I had it
 > -- but I
 > accidentally used it as one of my backup disks...  and its
 > gone.

 > If you have it please post...

DECLARE SUB CRC32Init ()
DECLARE FUNCTION FileCRC& (FileName$)
'QBCRC10.BAS - All PDS/QuickBASIC 4.5 CRC-32 Routine
'By Rich Geldreich 1992
'Use, abuse, I don't care!
'NOTE: All lines ending in an "_" underscore are continued on the next
'line. QuickBASIC users must make a few changes before this program will
'compile.

DEFINT A-Z

CONST LoadBuffer = 8192 'size of disk buffer in FileCRC

DIM SHARED CRCTable&(255)

'CRC table- I have the code that made this table, if anybody wants it.
DATA &H000000000,&H077073096,&H0EE0E612C,&H0990951BA,&H0076DC419
DATA &H0706AF48F,&H0E963A535,&H09E6495A3,&H00EDB8832,&H079DCB8A4
DATA &H0E0D5E91E,&H097D2D988,&H009B64C2B,&H07EB17CBD,&H0E7B82D07
DATA &H090BF1D91,&H01DB71064,&H06AB020F2,&H0F3B97148,&H084BE41DE
DATA &H01ADAD47D,&H06DDDE4EB,&H0F4D4B551,&H083D385C7,&H0136C9856
DATA &H0646BA8C0,&H0FD62F97A,&H08A65C9EC,&H014015C4F,&H063066CD9
DATA &H0FA0F3D63,&H08D080DF5,&H03B6E20C8,&H04C69105E,&H0D56041E4
DATA &H0A2677172,&H03C03E4D1,&H04B04D447,&H0D20D85FD,&H0A50AB56B
DATA &H035B5A8FA,&H042B2986C,&H0DBBBC9D6,&H0ACBCF940,&H032D86CE3
DATA &H045DF5C75,&H0DCD60DCF,&H0ABD13D59,&H026D930AC,&H051DE003A
DATA &H0C8D75180,&H0BFD06116,&H021B4F4B5,&H056B3C423,&H0CFBA9599
DATA &H0B8BDA50F,&H02802B89E,&H05F058808,&H0C60CD9B2,&H0B10BE924
DATA &H02F6F7C87,&H058684C11,&H0C1611DAB,&H0B6662D3D,&H076DC4190
DATA &H001DB7106,&H098D220BC,&H0EFD5102A,&H071B18589,&H006B6B51F
DATA &H09FBFE4A5,&H0E8B8D433,&H07807C9A2,&H00F00F934,&H09609A88E
DATA &H0E10E9818,&H07F6A0DBB,&H0086D3D2D,&H091646C97,&H0E6635C01
DATA &H06B6B51F4,&H01C6C6162,&H0856530D8,&H0F262004E,&H06C0695ED
DATA &H01B01A57B,&H08208F4C1,&H0F50FC457,&H065B0D9C6,&H012B7E950
DATA &H08BBEB8EA,&H0FCB9887C,&H062DD1DDF,&H015DA2D49,&H08CD37CF3
DATA &H0FBD44C65,&H04DB26158,&H03AB551CE,&H0A3BC0074,&H0D4BB30E2
DATA &H04ADFA541,&H03DD895D7,&H0A4D1C46D,&H0D3D6F4FB,&H04369E96A
DATA &H0346ED9FC,&H0AD678846,&H0DA60B8D0,&H044042D73,&H033031DE5
DATA &H0AA0A4C5F,&H0DD0D7CC9,&H05005713C,&H0270241AA,&H0BE0B1010
DATA &H0C90C2086,&H05768B525,&H0206F85B3,&H0B966D409,&H0CE61E49F
DATA &H05EDEF90E,&H029D9C998,&H0B0D09822,&H0C7D7A8B4,&H059B33D17
DATA &H02EB40D81,&H0B7BD5C3B,&H0C0BA6CAD,&H0EDB88320,&H09ABFB3B6
DATA &H003B6E20C,&H074B1D29A,&H0EAD54739,&H09DD277AF,&H004DB2615
DATA &H073DC1683,&H0E3630B12,&H094643B84,&H00D6D6A3E,&H07A6A5AA8
DATA &H0E40ECF0B,&H09309FF9D,&H00A00AE27,&H07D079EB1,&H0F00F9344
DATA &H08708A3D2,&H01E01F268,&H06906C2FE,&H0F762575D,&H0806567CB
DATA &H0196C3671,&H06E6B06E7,&H0FED41B76,&H089D32BE0,&H010DA7A5A
DATA &H067DD4ACC,&H0F9B9DF6F,&H08EBEEFF9,&H017B7BE43,&H060B08ED5
DATA &H0D6D6A3E8,&H0A1D1937E,&H038D8C2C4,&H04FDFF252,&H0D1BB67F1
DATA &H0A6BC5767,&H03FB506DD,&H048B2364B,&H0D80D2BDA,&H0AF0A1B4C
DATA &H036034AF6,&H041047A60,&H0DF60EFC3,&H0A867DF55,&H0316E8EEF
DATA &H04669BE79,&H0CB61B38C,&H0BC66831A,&H0256FD2A0,&H05268E236
DATA &H0CC0C7795,&H0BB0B4703,&H0220216B9,&H05505262F,&H0C5BA3BBE
DATA &H0B2BD0B28,&H02BB45A92,&H05CB36A04,&H0C2D7FFA7,&H0B5D0CF31
DATA &H02CD99E8B,&H05BDEAE1D,&H09B64C2B0,&H0EC63F226,&H0756AA39C
DATA &H0026D930A,&H09C0906A9,&H0EB0E363F,&H072076785,&H005005713
DATA &H095BF4A82,&H0E2B87A14,&H07BB12BAE,&H00CB61B38,&H092D28E9B
DATA &H0E5D5BE0D,&H07CDCEFB7,&H00BDBDF21,&H086D3D2D4,&H0F1D4E242
DATA &H068DDB3F8,&H01FDA836E,&H081BE16CD,&H0F6B9265B,&H06FB077E1
DATA &H018B74777,&H088085AE6,&H0FF0F6A70,&H066063BCA,&H011010B5C
DATA &H08F659EFF,&H0F862AE69,&H0616BFFD3,&H0166CCF45,&H0A00AE278
DATA &H0D70DD2EE,&H04E048354,&H03903B3C2,&H0A7672661,&H0D06016F7
DATA &H04969474D,&H03E6E77DB,&H0AED16A4A,&H0D9D65ADC,&H040DF0B66
DATA &H037D83BF0,&H0A9BCAE53,&H0DEBB9EC5,&H047B2CF7F,&H030B5FFE9
DATA &H0BDBDF21C,&H0CABAC28A,&H053B39330,&H024B4A3A6,&H0BAD03605
DATA &H0CDD70693,&H054DE5729,&H023D967BF,&H0B3667A2E,&H0C4614AB8
DATA &H05D681B02,&H02A6F2B94,&H0B40BBE37,&H0C30C8EA1,&H05A05DF1B
DATA &H02D02EF8D

PRINT "Zeek's Cheap File CRC-32 Utility"

CRC32Init                                   'read in the CRC table
FileSpec$ = COMMAND$                        'get filename
IF FileSpec$ = "" THEN INPUT "File"; FileSpec$
IF FileSpec$ = "" THEN END
PRINT "CRC-32:";
PRINT " <wait>";
CRC& = FileCRC&(FileSpec$)
PRINT STRING$(6, 29); HEX$(CRC&)

'Uses in-line coding to find a CRC-32 of a block of memory
'Although the "Length" variable is a signed integer, memory blocks >32k
'may be processed by this routine. (To process a block of memory 65535
'bytes long, -1, or &HFFFF, would be passed to this procedure, for
'instance.)
'
FUNCTION QBCRC& (BYVAL Segment, BYVAL Offset, BYVAL Length, BYVAL CRC&)
'QB4.5 users : FUNCTION QBCRC& (Segment,Offset,Length,CRC&)

'switch to input segment
DEF SEG = Segment

'Since we're going to calculate the CRC 4 bytes at a time, this FOR/NEXT
'takes care of all the oddballs left over...
FOR A = 1 TO Length AND 3
    CRC& = CRCTable&((CINT(CRC&) AND 255) XOR PEEK(Offset))
XOR (((CRC& AND &HFFFFFF00) \ 256) AND &HFFFFFF)
    Offset = Offset + 1
NEXT

---
 * Origin: Eric Ford (1:3632/1.6)