Converting vector to binary and summing it

6 次查看（过去 30 天）
William
William 2012-5-17
评论： Walter Roberson 2021-10-2
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
  2 个评论
Walter Roberson
Walter Roberson 2012-5-17
Is binary 11 + 11 to result in 10 ? That is, carry is used within the word, but overflow beyond the word is discarded?
Image Analyst
Image Analyst 2012-5-17
Which checksum algorithm are you using? http://en.wikipedia.org/wiki/Checksum

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Jan
Jan 2012-5-17
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);
  2 个评论
Saira Williams
Saira Williams 2020-11-30
Can you please show an example using CRC16 -CCITT?
Thank you!
Saira Williams
Saira Williams 2020-11-30
With a range of numbers 0-252. It would be really helpful your support.

请先登录，再进行评论。

更多回答（7 个）

Thomas
Thomas 2012-5-17
dec2bin gives the output as a string.. You will need to do more processing to actually get it numerically useful..
  2 个评论
William
William 2012-5-17
That was kind of my questions. As far As I know MATLAB treats Hex and Bin number like strings. This means I cannot to math to them
Walter Roberson
Walter Roberson 2012-5-17
subtract '0' (the character string that is a zero). That will get you numeric 0 and 1. But doing arithmetic on that can be tedious if you need to compute all the carries yourself. Hence my question, above which you have not answered :(

请先登录，再进行评论。

James Tursa
James Tursa 2012-5-17
What is the range of your numbers? You might be able to simply convert them to double, then add them, then mod the result with an appropriate value for your target wordsize.
Walter Roberson
Walter Roberson 2012-5-17
Use John D'Errico's MATLAB File Exchange contribution vpi package. Add the numbers without converting them to decimal. Take the result mod 2^(your word size) to get the result.
Walter Roberson
Walter Roberson 2012-5-17
Use the fixedpoint arithmetic package with the arithmetic properties set to "wrap" instead of "saturate".
William
William 2012-5-17
The basic idea behind this is that I am writing data to flash memory. I would like to take sixteen bytes and sum the entire 1024 number vector and take the twos compliment. I would then add the checksum I just created to the very last place when I wrote the data into flash.
Upon retirival of the data I would read the first number, store it, read the second number and add it to the first and store the result. The last number I add should be the two's compliment of the sum and adding the sum and it's two's compliment would mean I get zero as a result passing the checksum.
  4 个评论
显示 2更早的评论
Jan
Jan 2012-5-18
What is the purpose of the checksum? It will detect some 1-bit errors, but not all and even less 2 bit errors.
Walter Roberson
Walter Roberson 2012-5-18
Still it is a very common checksum, still in wide use as a "sanity check"

请先登录，再进行评论。

Walter Roberson
Walter Roberson 2012-5-18
convert the vector to 32 bit unsigned. sum() it. Extract the last 16 bits with bitget() or bitand() or mod()
  2 个评论
NGR MNFD
NGR MNFD 2021-10-2
hi dear
can you help me ? I want to know
How can I check the checksum of the force signal binary file? This force signal is measured by a 12-bit adc. I was able to display it through the following method.
fileID1=fopen('control1.let','r');
A= fread(fileID1, [3, 45000], 'uint8')'; % matrix with 3 rows, each 8 bits long, = 2*12bit
fclose(fileID1);
M2H= bitshift(A(:,2), -4);
M1H= bitand(A(:,2), 15);
PRL=bitshift(bitand(A(:,2),8),9); % sign-bit
PRR=bitshift(bitand(A(:,2),128),5); % sign-bit
M( : , 1)= bitshift(M1H,8)+ A(:,1)-PRL;
M( : , 2)= bitshift(M2H,8)+ A(:,3)-PRR;
N1 = reshape(M',[90000,1]); plot(N1);
Can I also check to see if it is correct or not? I do not know what code to use in MATLAB to calculate checksum? Please show me. Thank you.
Walter Roberson
Walter Roberson 2021-10-2
A= fread(fileID1, [3, 45000], 'uint8')'; % matrix with 3 rows, each 8 bits long, = 2*12bit
To be clear, the above code would store into A(1,1) then A(2,1), then A(3,1) then A(1,2) then A(2,2) then A(3,2) and so on. 3 rows, stored along the rows.
But when talking about binary data created by something else, it is common for data to be stored across the columns, rather than down the rows -- for the first entry to be A(1,1), then A(1,2), A(1,3) ... then after all the columns, A(2,1), A(2,2) and so on.
You need to be clear as to which arrangement you have.
Also your comment talks about 3 rows each each bits long, implying that it forms two 12 bit numbers. Is the implication But again it is important to know which order the data is stored in.

请先登录，再进行评论。

Fa Fa
Fa Fa 2012-6-25
Hi All, i like to create lookup tables of 511 local binary pattern, also from 10000000 bis 111111110, can somebody help, Thanks

类别

在 Help Center 和 File Exchange 中查找有关 Characters and Strings 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by