Hi group!

I need to rewrite a relatively simple CRC16 routine from C to VB6=2E This
should not be a problem if I wasn't a C virgin=2E I just can't get the
hang of C syntax=2E
Could someone please have a look at it and point out what I am doing
wrong=2E

There are two routines, one inits the table and the other performs the
actual CRC calc=2E
I took a stab at the init part, but since i expect the table to be 16
bit, I'm not very satisfied with the results=2E This is what I get:

CRC(0) =3D FEF1F   CRC(1) =3D EEF1F   CRC(2) =3D DEF1F   CRC(3) =3D CEF1F
CRC(4) =3D BEF1F   CRC(5) =3D AEF1F   CRC(6) =3D 9EF1F   CRC(7) =3D 8EF1F
=2E=2E=2E
CRC(248) =3D F7EF1F   CRC(249) =3D F6EF1F   CRC(250) =3D F5EF1F   CRC(251) =3D
F4EF1F
CRC(252) =3D F3EF1F   CRC(253) =3D F2EF1F   CRC(254) =3D F1EF1F   CRC(255) =3D
F0EF1F


Here is the C code:

// initialize the CRC16 table
extern void InitCRC16( void ) {
    int i, j ;
    WORD crc ;

    for ( i =3D 0 ; i < 256 ; i +=3D 1 ) {
        for ( crc =3D i << 8 , j =3D 0 ; j < 8 ; j +=3D i )
            crc =3D ( crc << 1 ) ^ ( ( crc & 0x8000 ) ? 0x1021 : 0 ) ;
        CRC16Table [ i ] =3D crc ;
    }
}


// calculate the CRC of a string  pointed at by p
extern WORD CalcCRC16 ( char * p ) {
    WORD CRC ;

    for ( CRC =3D 0xFFFF ;  *p !=3D 0 ; p++ )     // for all chars of a
string
        CRC =3D CRC16Table [ ( ( CRC >> 8 ) & 255 ) ] ^ ( CRC << 8 ) ^ *p
;
    return CRC ;
}


And my feeble VB attempt:

Option Explicit
Dim C16(255) As Long

Sub CRC_Init()
    Dim i As Long, j As Long
    Dim crc As Long
    For i =3D 0 To 255
        crc =3D i * 256
        For j =3D 0 To 7
            If crc >=3D &H8000 Then
                crc =3D (crc * 2) Xor &H1021
            Else
                crc =3D (crc * 2) Xor 0
            End If
        Next j
        C16(i) =3D crc
    Next i
End Sub


TIA,
Hugo

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