How delete last bit (LSB)

[arozma]

I have array with bits in each row and in one column. Now I ned to delete LSB (parity bit) and then assemble all 7 bits back together and split them in parts by 8 bits.

My idea was to put bits in matrix and then take from matrix first 7 columns. Problem is that I don't know hot put each bit in his own column. Next problem is how to convert this in bytes.

[crossrulz]

Can you give an example of what you want.  Posting a VI with default data is the best way.

What does your initial data look like (what data types)?  What is the end result you want?  Are you supposed to just use 7 bits in your byte or are you supposed to shift bits in from other bytes?

[arozma]

I will tray explain. I get 144 bytes from server. Those 144 bytes are separated in frames by 8 bits (7 data +1 parity). On the end I need to read message that is sent from server in ASCII code. Now I need delete parity bit so I can read message.

I have numbers in array like this

What I want is this

I must delete last column and put rest 7 bits together. This suposed to be my message. First 7 bytes is header.

I can post server and client. Server is in matlab. Main file of server in matlab is oddajnik.m. Server we got from professor.

I can't attach server.rar so I uploaded it on sendspace

Server in matlab

[crossrulz]

The simplest way would be to just use the Logical Shift function.  It can accept your array of bytes and perform a shift on each byte.  Set N to be -1 to perform a shift to the right (LSB is removed).

[arozma]

Now I need to put all bits together and make parts of 8 bits. I forget to write this in last post. Like you sad before I need shift bits in from other bytes.

If I have now 

1011011

1000110

1001111

then I should have

101101110001101001111 and from this parts of 8 bits

10110111

00011010

01111... and so on

Now I have 144 bytes. On the end I should have about 120 bytes. 

[udka]

Hi arozma, 

Please check the screenshot i have added and if it helps to solve your problem.

[altenbach]

While it would not be too diffiicult to combine the bits with numeric, it would need some extra code (e.g. similar to the old bit twiddling challenge) ;).

Unless performance is critical, It might be easier to convert to a boolean array, concatenate the subsets, and then convert back to a shorter U8 array. 

As a first step you need to tell us how your "bits" are represented in your code. Whatever you showed us made no sense:

 

You get a string. What is the format of the string? Is this a binary string (each byte representing 8 bits) or a string containing characters 0 and 1? You convert it to a U8 array, then into a 2D U8 array with one row, then back to the 1D array you originally had. This makes absolutely no sense.

[crossrulz]

This isn't exactly a simple task.  You can do with with boolean arrays.  I'm not happy with it, but it works.

I'm sure we can get this to work without changing data types, but I don't have the time to play with it right now.

[johnsold]

This should convert the string to an array of U8, remove the parity bit, shift the remaining bits to the right, and change it back to a string.

Lynn

[arozma]

---

@altenbach wrote:

While it would not be too diffiicult to combine the bits with numeric, it would need some extra code (e.g. similar to the old bit twiddling challenge) ;).

Unless performance is critical, It might be easier to convert to a boolean array, concatenate the subsets, and then convert back to a shorter U8 array. 

As a first step you need to tell us how your "bits" are represented in your code. Whatever you showed us made no sense:

 

You get a string. What is the format of the string? Is this a binary string (each byte representing 8 bits) or a string containing characters 0 and 1? You convert it to a U8 array, then into a 2D U8 array with one row, then back to the 1D array you originally had. This makes absolutely no sense.

---

It suposed to be a binary string. 

Yes, you have right. I tried many things before I get all data in one array. When I finaly made what I want, I leaved the code like it was. I fixed it now.

I learned basics of Labview a few years back. Since then I didn't worked with Labview. I tod I don't need to look basics again. Apparently I was wrong. 

Thank you all for your time and help. Now its on me to implement your code.