I receive byte data from a RS232RS-232 device with "Serial.read();"Serial.read();. Now I need to slice this down in bit-pieces:
value1: 15bits
value2: 7bits
value3: 9bits
value4: 12bits
and so on
Data
- value1: 15bits
- value2: 7bits
- value3: 9bits
- value4: 12bits
- and so on
Data from the stream (siwtchswitch them around for better understanding)
Byte 1: 00101100 => 00110100 (least significant byte first)
Byte 2: 10011011 => 11011001
Byte 3: 00110011 => 11001100
Byte 4: 11101000 => 00010111
Byte 5: 01001100 => 00110010
Byte 6: 01100111 => 11100110
- Byte 1: 00101100 => 00110100 (least significant byte first)
- Byte 2: 10011011 => 11011001
- Byte 3: 00110011 => 11001100
- Byte 4: 11101000 => 00010111
- Byte 5: 01001100 => 00110010
- Byte 6: 01100111 => 11100110
(now the least significant is first)
value1: 00110100.1101100[1] => 6956 (need to cut of the last bit of the second byte)
value2: 1.110011[00] => 103 (add the last bit of the second byte and cut off the last two bits of the third byte)
value3: 00.0001011[1] => 416 (add the last two bits of the third byte and cut off the last bit of Now the forth byte)
value4: 1.00110010least significant is first.111[00110] => 3737 (add the last bit of the forth byte and cut off the last 5 bits of the fifth byte)
- value1:
00110100.1101100[1]=> 6956
Need to cut of the last bit of the second byte - value2:
1.110011[00]=> 103
Add the last bit of the second byte and cut off the last two bits of the third byte - value3:
00.0001011[1]=> 416
Add the last two bits of the third byte and cut off the last bit of the fourth byte - value4:
1.00110010.111[00110]=> 3737
Add the last bit of the fourth byte and cut off the last 5 bits of the fifth byte
Now the question: howHow do I realiserealize this from programming side. I'm lost.
Cheers
EDIT and SOLUTION:
I gather the data into an array of bytes data[125]
Then I gather the relevant bytes per value and stack them together:
long var = (data[4]<<8) + (data[3]);
I shift them so the relevant bytes start first
var=var>>3;
Afterwards I mask them with the RIGHT mask
var=var & 0xFF;
For the example in my question:
long var = (data[1]<<8) + (data[0]); // I need two bytes
var=var>>1; // shift them to the right one bit
var=var & 0x7FFF; // mask it with "0111 1111 1111 1111"