Android Question LCR calculate

Lello1964 said:

I have to calculate LRC of a character string using this method:
can you help me ?

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'''uint8 LRC(const uint8* str, const uint16 length)
Sub LRC(A() As Byte, L As Int) As Byte

    '''uint8 r=0x00;
    Dim R As Byte = 0

    '''uint16 i=length;
    '''while (i--) {
    For I = 0 to L - 1
        '''r^=*str++;
        R = Bit.Xor(R, A(I))
    Next

    '''return r;
    Return R

End Sub

Lello1964 said:

C:

Public byte calculateLRC(byte[] data) {
    byte checksum = 0;
    For (int i = 0; i <= data.length - 1; i++) {
        checksum = (byte) ((checksum + data[i]) & 0xFF);
    }
    checksum = (byte) (((checksum ^ 0xFF) + 1) & 0xFF);
    Return checksum;
}

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Lello1964 said:

Example :
uint8 LRC(const uint8* str, const uint16 length)
{
uint16 i=length;
uint8 r=0x00;
while (i--)
r^=*str++;
return r;
}

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emexes said:

and your first major confusion will be that B4A Bytes are Java Bytes are signed (-128 to 127) rather than unsigned (0 to 255)

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emexes said:

Probably better to get it working in regular B4A first, rather than adding complexity and confusion eg:



producing a different check-value than:

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Lello1964 said:

can you help me ?

Click to expand...

    Dim lrc As LRC
    Dim values() As Byte = Array As Byte(15,63,255,128)
    Dim lrccrc As Byte = lrc.calculateLRC(values)
    Log($"$8{lrccrc}"$)