Another Delphi to Java transplantation

if(ReceivedMessage[slot].Message[1] = $FD) and
 (ReceivedMessage[ slot].MessageLength in [1..16]) and
 (ReceivedMessage[slot].Message[counter] = $FF) then
 begin
 index := 2;
 ReceivedMessage[slot].DataReady := TRUE;

 for counter := 1 to ReceivedMessage[slot].MessageLength do
 begin
 Inc(index);
< br /> if ReceivedMessage[slot].Message[index] <$F8 then
 ReceivedMessage[slot].Data[counter] := ReceivedMessage[slot].Message[index]
 else
 if ReceivedMessage[slot].Message[index] = $F8 then
 begin
 Inc(index);

 ReceivedMessage[slot].Data[counter] := ReceivedMessage[slot ].Message[index] or $F0;
 end
 else
 ReceivedMessage[slot].DataReady := FALSE; // Invalid data
 end;

 if ReceivedMessage[slot].DataReady = TRUE then
 begin
 Inc(index );

 if ReceivedMessage[slot].Message[index] <$F8 then
 ReceivedMessage[slot].CRC := ReceivedMessage[slot].Message[index] shl 8
 else
 if ReceivedMessage[slot].Message[index] = $F8 then
 begin
 Inc(index);

 ReceivedMessage[slot].CRC := (ReceivedMessage[slot].Message[index] or $F0) shl 8;
 end;

 Inc(index);

 if ReceivedMessage[slot]. Message[index] <$F8 then
 ReceivedMessage[slot].CRC := ReceivedMessage[slot].CRC or ReceivedMessage[slot].Message[index]
 else
 if ReceivedMessage[slot] .Message[index] = $F8 then
 begin
 Inc(index);

 ReceivedMessa ge[slot].CRC := ReceivedMessage[slot].CRC or ReceivedMessage[slot].Message[index] or $F0;
 end;

if(array[1]==0xFD && (array[2]>0 && array[2]<17) && array[pos]==(byte)0xFF)< br /> {
index=2;
for(int counter=1;counter{
 index++;
 if( array[index]<0xF8)
 data[counter]=array[index];
 else
 if(array[index]==0xF8)
 {
 index++ ;
 data[counter]=(byte)(array[index] | 0xF0);
 }
 else
 return 0xFC; 
}


index++;
short crc=0x0000;

if(array[index]<0xF8)
 crc=(short) (array[index]<< 8);
else
 if(array[index]==0xF8)
 {
 index++;
 crc=(short)((array[index] | 0xF0 ) << 8);
 }
index++;
if(array[index]<0xF8)
 crc=(short) (crc | array[index]);
else
 if(array[index]==0xF8)
 {
 index+ +;
 crc=(short)(crc | array[index] | 0xF0);
 }

msgcrc=new byte[] {(byte)(crc >> 8 & 0xff),(byte)(crc & 0xff));

byte test = (byte)255;
System.out.println(test); 

byte test = (byte)255;
 System.out. println(test == 255);

byte test = (byte)255;
 System.out. println((test & 255) == 255);

I am porting an old application written in Delphi to Java.
I have some trouble using this function, it calculates the CRC of the transmitted message .

This is the original code:

if(ReceivedMessage[slot].Message[1] = $FD) and
 (ReceivedMessage[slot].MessageLength in [1..16]) and
 (ReceivedMessage[slot].Message[counter] = $FF) then
 begin
 index := 2;< br /> ReceivedMessag e[slot].DataReady := TRUE;

 for counter := 1 to ReceivedMessage[slot].MessageLength do
 begin
 Inc(index);
< br /> if ReceivedMessage[slot].Message[index] <$F8 then
 ReceivedMessage[slot].Data[counter] := ReceivedMessage[slot].Message[index]
 else
 if ReceivedMessage[slot].Message[index] = $F8 then
 begin
 Inc(index);

 ReceivedMessage[slot].Data[counter] := ReceivedMessage[slot ].Message[index] or $F0;
 end
 else
 ReceivedMessage[slot].DataReady := FALSE; // Invalid data
 end;

 if ReceivedMessage[slot].DataReady = TRUE then
 begin
 Inc(index);

 if ReceivedMessage[slot].Message[index] <$F8 then
 ReceivedMessage[slot].CRC := ReceivedMessage[slot].Message[index] shl 8
 else
 if ReceivedMessage[slot].Message[index] = $F8 then
 begin
 Inc(index);

 ReceivedMessage[slot].CRC := (ReceivedMessage[slot]. Message[index] or $F0) shl 8;
 end;

 Inc(index);

 if ReceivedMessage[slot].Message[index] <$ F8 then
 ReceivedMessage[slot].CRC := ReceivedMessage[slot].CRC or ReceivedMessage[slot].Message[index]
 else
 if ReceivedMessage[slot].Message[index] = $F8 then
 begin
 Inc(index);

 ReceivedMessage[slot].CRC := ReceivedMessage[slot].CRC or ReceivedMessage[slot].Message[index] or $F0;
 end;

This is my Java code:

if(array[1]==0xFD && (array[ 2]>0 && array[2]<17) && array[pos]==(byte)0xFF)
 {
index=2;
for(int counter=1;counter< splMsg.nbytes+1;counter++)
{
 index++;
 if(array[index]<0xF8)
 data[count er]=array[index];
 else
 if(array[index]==0xF8)
 {
 index++;
 data[counter]=(byte) (array[index] | 0xF0);
 }
 else
 return 0xFC; 
}


index++;
short crc=0x0000;

if(array[index]<0xF8)
 crc=(short) (array[index]<<8);
else
 if (array[index]==0xF8)
 {
 index++;
 crc=(short)((array[index] | 0xF0) << 8);
 }
index++;
if(array[index]<0xF8)
 crc=(short) (crc | array[index]);
else
 if(array[index] ==0xF8)
 {
 index++;
 crc=(short)(crc | array[index] | 0xF0);
 }

msgcrc= new byte[] {(byte)(crc >> 8 & 0xff),(byte)(crc & 0xff)};

My function returns the transmitted CRC code most of the time, but sometimes it fails And return the last two bytes of the message. The last 3 bytes of the message are the CRC code (2 bytes) and the end of the message 0xff bytes.

Does it help?

Thank you,
Pedro

Remember:

Java bytes are signed .So:

byte test = (byte)255;
System.out.println(test);

will output: -1

and

byte test = (byte)255;
 System.out.println(test == 255);

An error will be printed, but

byte test = (byte)255;
 System.out.println((test & 255) == 255); 

Will do what I think you want to achieve (print true in this case).

To get an unsigned (byte) value, use (array [ index]& 255).

You will have to use 0xff for masking everywhere, otherwise you will get sign extended integers with byte values ​​greater than 127.

For comparison, you It is also possible to always perform conversion to bytes (e.g. if (test == (byte) 255)) but I think a single conversion should be adhered to, so I recommend masking with &0xff.

p>