MATLAB: Converting vector to binary and summing it

Question

Greetings,

I have a large vector 2048 x 1 of numbers I need to convert into binary and add them all togather (disregarding overflow) to create a checksum. Can I convert all the numbers to binary with a

dec2bin( decimal number) followed by a sum(vector)

Commands? This data is written to flash memory and we need to impliment a checksum

Thanks

Answer 1

What kind of checksum are you talking of?

If the numbers have a range of 0-255 a simple CRC32 could be helpful:

% Create CRC lookup table:
CRC_Table  = zeros(1, 256);
POLYNOMIAL = 79764919;      % 0x04c11db7L
shift24    = 16777216;
for i = 0:255
   % crc = bitshift(i, 24);
   crc = i * shift24;  % Faster
   for j = 0:7
      if crc >= 2147483648  % if bitget(crc, 32)
         %crc = bitand(bitxor(crc * 2, POLYNOMIAL), 4294967295);
         crc = rem(bitxor(crc * 2, POLYNOMIAL), 4294967296);
      else
         crc = crc * 2;
      end
   end  % for j
   % CRC_Table(i + 1) = bitand(crc, 4294967295);
   CRC_Table(i + 1) = rem(crc, 4294967296);
end  % for i
S  = 0;
c1 = 16777216;     % 2^24
c3 = 256;
c5 = 4294967296;   % 2^32: REM instead of BITAND
for n = 1:length(Data)
   m = rem(bitxor(fix(S / c1), Data(n)), c3);
   S = bitxor(rem(S * c3, c5), CRC_Table(m + 1));
end
S = sprintf('%.8X', S);

For another range, you can cast the values:

Data = typecast(Data, 'uint8');

Further hash methods can be found in: FEX: DataHash. E.g.:

Engine  = java.security.MessageDigest.getInstance('SHA-256');
Engine.update(tyepcast(Data, 'uint8'));
Hash    = typecast(Engine.digest, 'uint8');
HashHex = sprintf('%.2x', Hash);