convert negative integer to n (>32) bits?

I need convert negative integer to n (>32) bits binary. I fould 'Integer to Bit Converter' block having limit of number of bits up to 32, and functions 'de2bi' or 'dec2bin' only applicable for non-negtive integer. What can I do? Many thanks!!

[Jan]

Please post exactly what the type and dimensions of the inputs and outputs are. It is impossible to guess such details. Do you want to solve it in Simulink or Matlab?

[Qinghua]

For example, input: -2199023255552 (-2^41), output: signed 43 bits binary.

I'd like to know how to solve it both in Simulink and Matlab.

Thank you for the help!

[Jan]

There is no "signed 43 bits" type in Matlab. What exactly do you want as output?

If you convert it to a INT64, the sign will be stored in the most significant bit.

[Qinghua]

I have to simulate the output from FPGA which has 43 signed bits and 35 signed bits registers.

Is it possible to program such convertion in Matlab?

[Qinghua]

Thanks for advising. I tried:

>> A=de2bi(typecast(int64(-2^41),'uint64'),64,'left-msb');

>> B=A;

>> B(2:22)=[];

By this I can extract the signed 43 bits. But a new problem came when I tried with a smaller negetive integer:

>> de2bi(typecast(int64(-2),'uint64'),64,'left-msb');

It looks the N should be less than -2^16. For practical reason, I need to convert all input data to a same format (INT64). How can I do?

Answer 1

[Walter Roberson]

The Fixed Point Toolbox is probably what you want.

[Qinghua]

Which function can I use exactly?

[Fangjun Jiang]

The Fixed Point Toolbox of Simulink. http://www.mathworks.com/products/simfixed/?s_cid=global_nav

[Walter Roberson]

I'm not convinced this is a Simulink issue?

[Fangjun Jiang]

The OP had another question indicating that. But I guess that MATLAB has a Fixed-Point Toolbox too.

[Qinghua]

No matter Simulink or Matlab. I can't figure it out by neither of them: Is it possible to convert the nagtive integer e.g. -2199023255552 (-2^41), or -2 to 43 signed bits (or even 64 bits)?

Which functions can I use?