===========================================================================
 BBS: The Abacus * HST/DS * Potterville MI
Date: 03-01-93 (03:01)             Number: 56
From: DIK COATES                   Refer#: NONE
  To: JIM COYLE                     Recvd: NO  
Subj: Crc32 2/2                      Conf: (35) Quick Basi
---------------------------------------------------------------------------
Part 2 of 2
- - - - - CUT HERE WITH SHARPENED END OF BEER CAN - - - - -
crcstr  proc    far
        push    bp
        mov     bp,sp           ;create stack frame

        les     si,crcptr
        mov     ax,es:[si]
        mov     dx,es:[si+2]    ;dx:ax -> crcout

        mov     cx,srclen       ;cx    -> source length
        les     si,srcptr       ;es:si -> source buffer
        mov     di,offset crctable     ;cs:di -> crctable

crcNext:
        mov     bh,al           ;save crcout & 0x000000ff
        mov     al,ah           ;(crcout >> 8) & 0x00ffffff
        mov     ah,dl
        mov     dl,dh
        xor     dh,dh
        mov     bl,es:[si]  ;*src++
        inc     si
        xor     bl,bh       ;crcval & 0x000000ff
        xor     bh,bh
        shl     bx,1
        shl     bx,1
        xor     ax,cs:[di+bx]
        xor     dx,cs:[di+bx+2]

        dec     cx
        jcxz    crcDone

        mov     bh,al       ;save crcout & 0x000000ff
        mov     al,ah       ;(crcout >> 8) & 0x00ffffff
        mov     ah,dl
        mov     dl,dh
        xor     dh,dh
        mov     bl,es:[si]  ;*src++
        inc     si
        xor     bl,bh       ;crcval & 0x000000ff
        xor     bh,bh
        shl     bx,1
        shl     bx,1
        xor     ax,cs:[di+bx]
        xor     dx,cs:[di+bx+2]

        dec     cx
        jcxz    crcDone

        mov     bh,al       ;save crcout & 0x000000ff
        mov     al,ah       ;(crcout >> 8) & 0x00ffffff
        mov     ah,dl
        mov     dl,dh
        xor     dh,dh
        mov     bl,es:[si]  ;*src++
        inc     si
        xor     bl,bh       ;crcval & 0x000000ff
        xor     bh,bh
        shl     bx,1
        shl     bx,1
        xor     ax,cs:[di+bx]
        xor     dx,cs:[di+bx+2]

        dec     cx
        jcxz    crcDone

        mov     bh,al       ;save crcout & 0x000000ff
        mov     al,ah       ;(crcout >> 8) & 0x00ffffff
        mov     ah,dl
        mov     dl,dh
        xor     dh,dh
        mov     bl,es:[si]  ;*src++
        inc     si
        xor     bl,bh       ;crcval & 0x000000ff
        xor     bh,bh
        shl     bx,1
        shl     bx,1
        xor     ax,cs:[di+bx]
        xor     dx,cs:[di+bx+2]

        loop    crcNext

crcDone:
        les     si,crcptr
        mov     es:[si],ax
        mov     es:[si+2],dx

        pop     bp
        ret     10                  ;dispose of 10 parameter bytes
crcstr endp

code ends
end
- - - - - CUT HERE WITH SHARPENED END OF BEER CAN - - - - -
Regards Dik, Oshawa, Canada

... Wanted Dead or Alive: 1 pink rabbit with a drum
___ Blue Wave/QWK v2.10

--- Maximus 2.00
 * Origin: Durham Systems (ONLINE!) (1:229/110)
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===========================================================================
 BBS: The Abacus * HST/DS * Potterville, MI
Date: 03-08-93 (12:19)             Number: 249
From: CORIDON HENSHAW              Refer#: NONE
  To: BRYAN NYLIN                   Recvd: NO  
Subj: Looking For Crc32 Code         Conf: (35) Quick Basi
---------------------------------------------------------------------------
Hello Bryan!

Friday March 05 1993, Bryan Nylin writes to All:

 BN> I am looking for a function that will return the CRC-32 code for a
 BN> string that is passed to it.

I should make this a FAQ or something...

Here's CRC32 and CRC16 code:

=== BEGIN: CRC.BAS ===
DECLARE FUNCTION CRC16& (Block$)
DECLARE FUNCTION CRC32& (Block$)

DEFINT A-Z
FUNCTION CRC16& (B$)      'Calculates CRC for Each Block

DIM Power(0 TO 7)                              'For the 8 Powers of 2
DIM CRC AS LONG

FOR I = 0 TO 7                                 'Calculate Once Per Block to
   Power(I) = 2 ^ I                            ' Increase Speed Within FOR J
NEXT I                                         ' Loop
CRC = 0                                        'Reset for Each Text Block
FOR I = 1 TO LEN(B$)                           'Calculate for Length of Block
   ByteVal = ASC(MID$(B$, I, 1))
   FOR J = 7 TO 0 STEP -1
      TestBit = ((CRC AND 32768) = 32768) XOR ((ByteVal AND Power(J)) = _ Power(
J))
      CRC = ((CRC AND 32767&) * 2&)
      IF TestBit THEN CRC = CRC XOR &H1021&     ' <-- This for 16 Bit CRC
   NEXT J
NEXT I
CRC16& = CRC                               'Return the Word Value
END FUNCTION

DEFSNG A-Z
FUNCTION CRC32& (B$)      'Calculates CRC for Each Block

DIM Power(0 TO 7)                              'For the 8 Powers of 2
DIM CRC AS LONG

FOR I = 0 TO 7                                 'Calculate Once Per Block to
   Power(I) = 2 ^ I                            ' Increase Speed Within FOR J
NEXT I                                         ' Loop
CRC = 0                                        'Reset for Each Text Block
FOR I = 1 TO LEN(B$)                           'Calculate for Length of Block
   ByteVal = ASC(MID$(B$, I, 1))
   FOR J = 7 TO 0 STEP -1
      TestBit = ((CRC AND 32768) = 32768) XOR ((ByteVal AND Power(J)) =_ Power(J
))
      CRC = ((CRC AND 32767&) * 2&)
      IF TestBit THEN CRC = CRC XOR &H8005&     ' <-- This for 32 Bit CRC
   NEXT J
NEXT I
CRC32& = CRC                               'Return the Word Value
END FUNCTION
=== END ===

If you'd like a FAST ASM version, just ask.

Coridon Henshaw / Sirrus Software / QBCIMR FTSC Standards Technician / SM DEV

--- GEcho 1.00
 * Origin: TCS Concordia - Mail Only - Toronto, Ontario (1:250/820)
SEEN-BY: 1/211 11/2 4 13/13 101/1 108/89 109/25 110/69 114/5 123/19 124/1
SEEN-BY: 153/752 154/40 77 157/2 159/100 125 430 950 203/23 209/209 280/1
SEEN-BY: 390/1 396/1 15 397/2 2230/100 3603/20