Is the famous HPACK demo diagram wrong? - http-headers

I was so much confused by 19 in the rightmost picture, which IMHO would be 4 [2].
The slide is from https://docs.google.com/presentation/d/1r7QXGYOLCh4fcUq0jDdDwKJWNqWK1o4xMtYpKZCJYjM/edit#slide=id.gfd0e3427_048
[2] https://http2.github.io/http2-spec/compression.html#rfc.section.A

Yes looks wrong to me too, and I agree it should be 4 for :path and not 19 for accept.
The presenter's book High Performance Browser Networking (available online for free) has this in the HPACK section:
Which, as you can see, did include the accept header so suspect they just made a typo when they simplified the example for the slides.

Related

mediapipe KNIFT template matching example: using own pics doesn not work properly - how does the example actually work?

i followed the example steps to create an own android app KNIFT template matching example like the 3 dollar bill example on the mediapipe website...did anyone of you build this and know how this really works? I cant get a clear documentation.
My approach to run my own example as suggested on the mediapipe: I have three example pics in my folder (and I did all the build steps with them) that are detected and framed indeed....but not as often and not as correctly as in the dollar bill example (which works fine for me, every bill is detected and framed and labeled as expected).
Also my labeling doesnt work properly. Sometimes it does partly, sometimes it is labeled but incorrect. What does the framework do with my pics and labels and how to optimize my own example?
Any help is appreciated...
regards, fabian

Windows 8 app: Best way to build this fency different sized layouts?

I had a look at the windows 8 app development resources and there are always this fency layouts with different templated items (see below) but I could not find a sample how this should be done.
Does anyone have a sample or even know how to do it?
update
Maybe the question is a little bit to unclear.
I want to know how the designs you can see in all the Windows 8 demo apps and in the image above are done. For example often there are different headlines (friends, restaurants, wishlist,...) with lists below. This lists contain sometimes images that are, lets say 10x10, and others are 20x10 (see 3 col in the image). Is there a build in and easy way to achieve this or do they just stack lists and templates (using stackpanels and such things) somehow?
I have found something in the documentation of the developmentcenter:
http://msdn.microsoft.com/en-US/library/windows/apps/xaml/hh465351
There is a control called "VariableSizedWrapGrid" which handle this layouts!
http://msdn.microsoft.com/en-US/library/windows/apps/xaml/windows.ui.xaml.controls.variablesizedwrapgrid

How can I add some detection or correction code in a 48bits message?

I'm developing a OCR tool reeds a set of symbols which represent 2 bits each.
For example:
{ ---> 00
} ----> 01
Always I have a 48 bits code so I have 24 symbols.
I need to implement a detector or correction of errors in Objective-c (I'm developing an application for Mac).
My only requirement is that the code is as small as possible. I have a 48-bit (which represents 24 Sibol) and do not want to add many more to my design.
I have tried to implement this code:
http://code.google.com/p/rscode-objc/
But it is outdated, I get many errors and is designed for messages of 255 bytes (and of course I do not know how to adapt). If somebody can help me to adapt it, it would be great.
If you need further details, let me know.
Thank you.
You can try these two files for a complete CRC64 implementation (from the tags you added, I thought you'd be interested in CRC):
CRC64.h:
http://pastie.org/3227564
CRC64.c:
http://pastie.org/3227559
I have finally use the Reed-Solomon code: http://code.google.com/p/rscode-objc/
But thank you for your answer H2CO3 :)

Does sample code exist for Squeak Smalltalk?

can anybody give some hints on squeaksource or things like that, they can provide mcz sample code focuse on simple add, reduce, multiplication, division calculation?
http://www.world.st/ is an awesome access point for all things Smalltalk. It has links to many free books, including Stephan's excellent suggestion. There are also links to many Smalltalk mailing lists, like the Squeak beginners list, where you can get many basic (and not so basic) questions answered.
It's hard to answer very general questions (like yours). If you are more specific, you'll get better answers. Especially if you try something on your own first and then explain what you did and where you got stuck.
UPDATE:
It seems you're asking if you can see what's going on behind the scenes when code is executed. In the Browser, you can choose to see the bytecodes that it's compiled into.
In your (1+2) * 3 example, if you save this in a method, and click the "source" button in the Browser ("view" in OmniBrowser), and choose "byteCodes", you will see:
17 <76> pushConstant: 1
18 <77> pushConstant: 2
19 <B0> send: +
20 <20> pushConstant: 3
21 <B8> send: *
22 <87> pop
23 <78> returnSelf
Did you already read Squeak by Example?
While its not really sample code, my video tutorial series, Squeak from the very start, may give you insights: http://www.youtube.com/playlist?list=PL6601A198DF14788D&feature=viewall

What implementation of Forth should I use for learning Forth? [closed]

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I want to start learning Forth (like in the related Stack Overflow question Is it practical to learn and use Forth?). I see that there are many implementations. I would like to use a
ANS 1994 compatible version (if reasonable, but sticking to the standard might be good)
small and compact implementation, I don't want a full OS.
Windows
easy to use, I am new to Forth ;-)
What particular implementation can be recommended?
Win32Forth is really fantastic, as mentioned above. It has a nice integrated development environment and is a pretty modern implementation that seems to match up very well with the standards as well as including some more experimental but widely-accepted features.
I use Gforth, but I also use Vim to edit source files. :) Gforth is good and "classic" as far as the features it supports. It gives you a very "old school" Forth experience without being overly quirky to use. (Some free Forths do odd things with their command lines and such - I use Brodie's "Starting Forth" as the model of how a Forth interpreter should behave.)
I looked at SwiftForth, which is a very nice "high tech" Forth system that goes well beyond what the classic Forths offer in terms of language features and really brings Forth into the modern programming world. If you want to actually do Forth programs professionally, SwiftForth looks like it can handle just about anything you want to do with it.
Some time ago I evaluated 4tH, an implementation of Forth.
I think it meets all of
your requirements. For instance the compiler is only 61 KB. There is also full support for floating point numbers, important if you want to
try to use it for technical/scientific purposes.
4tH runs on most operating systems, including MS-DOS, MS-Windows (both 16 bit and 32 bit), Linux, Coherent, AIX, SunOS, BOS, BSD, Mac OS X, BeOS, RISC OS, etc. Download (Windows installer, 1.5 MB, includes the manual). Manual (PDF, 1.1 MB).
There is an active community centered around the Google Group 4tH-compiler.
For instance today I received two messages.
Please note that in 4tH you can't define your own defining words (words executing at compile time). This is not a serious
limitation, unless you want to cover advanced Forth features.
To get you started (as this is not very clear from the manual or the interactive compile), after installation copy the compiler, 4th.exe, to an empty folder, make two files in this directory, HelloWorld.bat and HelloWorld.4th, and run HelloWorld.bat:
HelloWorld.bat:
4th.exe cx HelloWorld.4th
pause
HelloWorld.4th:
: hello ." Hello from XYZ!" cr cr ;
hello
SwiftForth. It isn't self-consciously small and compact; it just happens to be. It's easy to use (LOCATE WH EDIT , a nicer than usual WORDS), comes with two books, and has an excellent mailing list with over a decade of archives. The evaluation version won't let you compile turnkey apps or DLLs; it still provides an excellent console for a student, and can support scripts in the usual ways. Quick Windows examples:
: sleep-monitor ( -- )
HWND_BROADCAST WM_SYSCOMMAND SC_MONITORPOWER 2 SendMessage drop ;
library dnsapi.dll
( ... DLL imports, constants ... )
variable results
: DnsQuery ( z -- res )
DNS_TYPE_A 0 NULL results NULL DnsQuery_UTF8 ;
: resolves? ( z -- f )
DnsQuery if false exit then
results # DnsRecordListFree true ;
\ an example use of the dialog compiler
\ this compiled DSL is an example of something that 4th
\ precludes with its "not ... serious limitation"
DIALOG (HELLO-ABOUT)
[MODELESS " About Hello" 10 10 120 70
(FONT 8, MS Sans Serif) ]
\ [class text id x y sx xy ]
[CTEXT " HELLO" -1 10 10 100 10 ]
[CTEXT " (C) 1997 Forth, Inc." -1 10 25 100 10 ]
[CTEXT " http://www.forth.com" -1 10 35 100 10 ]
[DEFPUSHBUTTON " OK" IDOK 35 50 50 14 ]
END-DIALOG
Download Gforth for PC and Android.
Tinker with it using it as a calculator, solving simple problems, Fibonacci, solving the quadratic a b c, etc.
I realise they might not meet all your requirements but the following Forth-like languages might also interest you from a learning perspective.
Factor
RetroForth
Additionally, I have found the Re-Factor blog to be a good introduction to Factor.
If you can find a copy of FORTH Inc's old polyFORTH, and an old x86 that can run it, this is the language used in Leo Brodie's original "Starting FORTH". It is a clean and very robust FORTH.
I recommend ciforth, as you're a Windows user the version built for Windows is known as wina: an MS-WIndows NAtive Forth.
ciforth is a small system written in NASM assembler, and comes with a similar interface for a wide variety of systems. It's small, fast, classic (blocks ftw), easy to use as it's old school, comes with a ton of documentation and a wordlist that isn't overwhelming like Gforth's (the wordlist for Lina is here, the only difference between lina and wina are in words that access the underlying OS: linux/MS-Windows).
Gforth has a lot of bloated definitions and some of Starting Forth won't work in it, for example.
The only thing the official release of ciforth lacks is a floating point stack, but Forth can deal with fixed point incredibly well (if one reads Starting Forth, one learns about how to use it).
wina versions can call dll functions just fine, in 32 and 64 bit, but can also make turnkey applications that call dll functions.
Beta releases have floating point as a loadable extension.
Win32Forth worked well for me.
durexForth is an ANS compliant C64 Forth and very small.