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I'm working on an embedded communication protocol where bytes will be transmitted. In my packets, I can only allocate 7 bits for integrity check. If I just sum up the bytes module 256 and then throw out the MSb, then I suspect errors in the first bit in each byte would not be detected. Can someone please recommend a computationally inexpensive method that is a little more robust? It needs to be computationally inexpensive because it could potentially run on small, slow microcontrollers.
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You could XOR the nibbles of each byte together and use aggregate those values as your checksum. It's not perfect, multiple errors in a byte could lead to collisions, but it's better than the alternative and should still be speedy.
"Never attribute to malice that which can be explained by stupidity."
- Hanlon's Razor
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Hi,
I added a submenu to the Windows explorer for directorys. Unfortunately not all the items are visible.
Is there a way to show more items than 16 incl all subitems?
I was working with ExtendedSubCommandsKey.
I really mean menutems and not fileitems.
jan
Sorry if this is not the right place to ask this. The program is writen in vb.net but the question is stricly Windows.
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I found that to but I was hoping that now with Windows 10 there is a way to enlarge that number.
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I have two datasets A & B.
A=>{10,12,24,14,35}
B=>{11,12,23,15,24}
to compare the similarity between the two datasets, let's say we employ two methodologies.
MEAN & STANDARD Deviation.
Difference between MEAN(A) & MEAN(B) is X % (Percentage)
Difference between STDEV(A) & STDEV(B) is Y % (Percentage)
Now to say a final, overall difference between the two datasets, can I say X% + Y%?
I'm sure it's wrong. 
What's the best way to indicate the overall difference observed when we have two results expressing it in different percentages?
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Nand32 wrote: Difference between MEAN(A) & MEAN(B) is X % (Percentage)
Difference between STDEV(A) & STDEV(B) is Y % (Percentage)
Now to say a final, overall difference between the two datasets, can I say X% + Y%?
I'm bad at math, but both are ways to measure "differences".
Two ways of determining differences between strings is by looking at length, and the first character. I can't simply add the two to get a "better difference".
Decide whether the length, or the first character is more telling of the "difference" you seek. FWIW, there's more ways even than those two to quantify how they differ; there's weighted moving averages and more of that arcane stuff.
Give it some time and someone who is good at maths will ask you what type of difference you seek.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Eddy Vluggen wrote: weighted moving averages
I was just thinking about it. I guess this is good enough. thanks 
Will watch out for an expert opinion though. 
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You have two types of measurements. Adding the 2 "different" types of percentages is meaningless relative to considering the percentages individually. In theory, they could cancel each other out, and you're left with "zero", even though they are "different".
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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Composition of percentages would involve multiplication rather than addition. But it wouldn't make any more sense, imho. Two series could have same mean but different standard deviations. In this case the multiplication would yield zero, which wouldn't tell much about current situation, and could even be misleading by tricking one into thinking that both series are equal/equivalent.
"Five fruits and vegetables a day? What a joke!
Personally, after the third watermelon, I'm full."
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How about averaging the two difference? Or even better with weighted-average to have more control over which part of the composition matters more to us.
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I am not aware of a way to combine those two distinct measurements into something really meaningful. Just test your assumptions with some result sets, and see whether you can make valuable observations with them. Beware of edge cases, especially those where zero is involved.
"Five fruits and vegetables a day? What a joke!
Personally, after the third watermelon, I'm full."
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Hi everyone,
I am working on a browser-based document scanning application for IE it is fine as we can do scanning through ActiveX or Add-ons etc but when it comes to modern browsers like latest chrome, firefox and edge it is very hard to call any .exe or other is related functions from client-side .. What is the option to invoke scanner from modern browsers and do necessary file I/o on client end... Please don't mention proprietary software I prefer to work with open-source solutions.. regard
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Since there's probably a human required to "load the scanner", having the browser control the action doesn't seem to make a lot of sense. Every scan usually involves creating a file, which is what you should be interested in.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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Kami Dehlvi wrote: it is very hard to call any .exe or other is related functions from client-side .
Deliberately so, as it prevents ther browser from performing actions that it should not be allowed to do.
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If your intending for a user to go to a third-party website and the site somehow controls a scanner they may or may not have, then that's a deadend. That goes against everything a browser is supposed to do.
Your site should direct them to upload the scanned file, but the actual generation is in the users hands...obviously your site could provide guiding instructions.
If your creating a scanner client and just want to use HTML for the interface, that's doable.
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Thanks for your reply,
I am surprised to see replies, that document scanning is not possible from the client-side. well, it is for sure that secure browsers not allowing this access.
But the question arrives here how can we enable a client-end document scanner to be accessed using the web, any new technology, way or possibility.
Please share,
regards
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Kami Dehlvi wrote: how can we enable a client-end document scanner
You cannot do it from a browser for the reasons already stated.
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Well the other solution could be that the user installs a local piece of software, that in effect connects to a 'control' server and connects to the locally connected scanner. Then a separate web site 'could' send a message to the control server which then would tell the local software to act.
But note that whole interaction makes no sense, far to much of the process is the user interacting with the physical scanner. So controlling 'remotely' via web sites doesn't help the process at all.
Now if your actual concern is that the 'scanning, file, upload file to your site' etc process isn't as easy as it could be. Then yes I could understand that, but the solution would be a downloaded piece of software that interacts with all scanner types, scans and uploads the file to just your servers.
I think most people hitting this concern have decided its better to educate (via the websites) the users on how to do the process rather than solve it with software.
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At my company there are few programmers that are either lazy, non-quality minded, unintelligent or all of the above. I have written a driver and they have to provide a GUI on top of that driver. Normally, my driver would be very thin with no restrictions, but knowing the quality of my co-workers I have added a validation layer on top of the low-level drivers because I care about the success of my company. How would you recommend I minimize the risk that they bypass the validation layer and call the low-level functions directly? Should I encode my variables, function names and parameters, using some kind of ASCII encoding algorithm, so it's difficult to understand what the functions do? Should I name my low-level functions something like KEVIN_JEFF_AND_MARK_NEVER_CALL_THIS_FUNCTION_writeMemory(uint32_t addr, uint8_t value)? Any other ideas? I've already talked to my boss and he thinks it's too difficult to find new programmers to get rid of them.
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You provide them with an "interface" that only exposes the methods and properties that you want them to see. Most programming languages (which you didn't specify) have "interface" patterns.
Designing C# Software With Interfaces - Simple Talk
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
modified 14-Dec-19 13:02pm.
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The programming language is C#. We don't want to use a dll because then we can't step through the code when debugging.
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Dll's don't preclude debugging.
Use a wrapper class then. Give the "bad programmers" the wrapper that calls your dll's "open" methods, then make up a stupid name for the dll that they can't guess: StupidProgrammer.dll, for example. Though they have to add stupid dll to the project too.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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make your functions private and call them from the validation layer
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