Convert a string with a hex representation of an IEEE-754 double into JavaScript numeric variable -

-

Let me say I have a hex number "4072508200000000" and I want the floating point number that it shows in IEEE-754 (293.03173828125000). The double format is inserted into the JavaScript variable.

I can think in a way that calls for masking and pow (calls), but is this a simple solution?

A client-side solution is required.

This may be helpful, it is a website that allows you to enter the hex encoding of an IEEE-754 and get an analysis of Mentisa and Exponent.

Because people always ask "why?", Here's why: I am trying to fill the existing, but incomplete implementation of Google's Procol Buffers (protobuf).

I do not know a well, this can definitely be done in a difficult way, here's JavaScript There is a perfectly accurate example in: 

  js> a = 0x41973333 1100428083 JS & gt; (A and 0x7fffff | 0x800000) * 1.0 / Mathipo (2,23) * Math.p. (2, (A &>; 23 & amp; 0xff) - 127) 18.899999618530273

A production implementation should be kept in mind that most areas have magic values, which are usually implemented by specifying a specific explanation for being the largest or smallest. Therefore, NaN s and infinities Find out the above example should be checked for negative (another amp 0x80000000)

Update: OK, let me know You can not expand the above technique directly because the internal SS representation is a double, and with its definition it can handle a little bit of length 52, and it can handle more than 32 Can not go.

OK, to double you first cut as a string cut 8 digits or 32 bits; processed with a different object Then: 

  JS> A = 0x40725082 1081233538 Sector S & gt; (e 0xfffff | 0x100000) * 1.0 / Mthipo (2, 52 - 32) * Mthkpo (2, (e ;; 52 - 32 & amp; 0x7ff) - 1023)) 293.03173828125 JSA & gt;

I put the example above because it is from OP. A difficult case occurs when the value of less than 32 bits is true. Here is the conversion of 0x40725082deadbeef, a full-scale double: 

  js> A = 0x40725082 1081233538 JS & gt; B = 0xdeadbeef 3735928559JS & gt; E = (A & gt; 52 - 32 & amp; 0x7ff) - 1023 8 JS & gt; (Another amp 0xfffff | 0x100000) * 1.0 / Mathipo (2,52-32) * Math.p. (2, E) + B * 1.0 / Mathipo (2, 52) * Math.p. (2, E) 293.031 9506442019JS & gt;

Some obvious subexpressions can factor you, but I have left it this way so that you can see how it is related to the format.


Comments

Post a Comment

Popular posts from this blog

MySql variables and php -

-
I am getting an error with php in order to format mysql_query () in php to format this string What is the right way? SELECT SELECT SELECT (*) Agents @AgentCount; User_Agent_English, User_Angent_Oursal, US.___Gent_Aginal, COUNT (User_Agent_Percade) ACC, COUNT (*) / (AgentCount) Percentage by agents user_agent_preser order DEC limit limit 50; In PHP, how am i setting $ query $ query = "SELECT count (*) agents @ agentcount; SELECT user_agent_parsed, User_agent_original , COUNT (user_agent_parsed) ascount, COUNT (*) / (@AgentCount) as a percentage by user_agent_parced by URI date DESC limit 50 "; This exact query will work properly if I put it in MySQL directly through a command line session. Do I need to release two separate php calls from mysql_query () and store the results first? I get the following error: There is an error in your SQL syntax; Instead of using a sub-selection and instead of using the 'SELECT user_agent_parsed, user_agent_original, ne...
Read more

url rewriting - How to implement the returnurl like SO in PHP? -

-
This URL should work even after the rewrite. Is this possible? Otherwise, I can only hardcoded everything If you are trying to create a login system with redirection You need to use the HTTP_REFERER header to find out where the user came from so that you can send it back there. The best way to do this is to use something like this in your login form: // - Login php & Lt; Input type = "password" name = "password" /> & Lt; Input type = "hidden" name = "returnrelale" value = "& lt ;? php echo $ redirectURL ;? & gt;" / & Gt; & Lt; / Form & gt; Please note that some ISP, browser or proxy will delete the referrer header, so you can not rely on each user to work fully. If you use a statement, to check whether the header exists or not, you can send those users back to the homepage or whatever. Edit If you are looking to use $ _SERVER ['REQUEST_URI'], if you are running Apache It sho...
Read more

Which Python client library should I use for CouchdB? -

-
I am starting to experiment with CouchDB because it looks like we have the right solution to certain problems That all the work will be on a new project, which does not have any legacy dependency, which the client library will suggest you use, and why? If we overlap any of the OS. Freeband is available only in the collection of its ports, but asks to use the library's project website. None of those people are Ubuntu, which is only with ships, since those two OSAs are not common in libraries, I am probably installing something from source (and hopefully if I have time, then Ubuntu and FreeBSD People pack the package). For those interests, I want to use CouchDB as a convenient intermediate storage space for data passed between different services - think of a message bus system, but less formalities with. For example, we have daemons that download and pars the web page, then send an interesting bit to other daemons for further processing. Many of them are ill-defined until the...
Read more