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  • How to receive packets on the MCU's serial port?

    - by itisravi
    Hello, Consider this code running on my microcontroller unit(MCU): while(1){ do_stuff; if(packet_from_PC) send_data_via_gpio(new_packet); //send via general purpose i/o pins else send_data_via_gpio(default_packet); do_other_stuff; } The MCU is also interfaced to a PC via a UART.Whenever the PC sends data to the MCU, the *new_packet* is sent, otherwise the *default_packet* is sent.Each packet can be 5 or more bytes with a pre defined packet structure. My question is: 1.Should i receive the entire packet from PC using inside the UART interrut service routine (ISR)? In this case, i have to implement a state machine inside the ISR to assemble the packet (which can be lengthy with if-else or switch-case blocks). 2.Detect a REQUEST command (one byte)from the PC in my ISR set a flag, diable UART interrupt alone and form the packet in my while(1) loop by polling the UART?

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  • Floating point precision nuances.

    - by user247077
    Hi, I found this code in NVIDIA's cuda SDK samples. void computeGold( float* reference, float* idata, const unsigned int len) { reference[0] = 0; double total_sum = 0; unsigned int i; for( i = 1; i < len; ++i) { total_sum += idata[i-1]; reference[i] = idata[i-1] + reference[i-1]; } // Here it should be okay to use != because we have integer values // in a range where float can be exactly represented if (total_sum != reference[i-1]) printf("Warning: exceeding single-precision accuracy. Scan will be inaccurate.\n"); } (C) Nvidia Corp Can somebody please tell me a case where the warning would be printed, and most importantly, why. Thank you very much.

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  • Python - Finding unicode/ascii problems

    - by user330739
    Hi all, I am csv.reader to pull in info from a very long sheet. I am doing work on that data set and then I am using the xlwt package to give me a workable excel file. However, I get this error: UnicodeDecodeError: 'ascii' codec can't decode byte 0x92 in position 34: ordinal not in range(128) My question to you all is, how can I find exactly where that error is in my data set? Also, is there some code that I can write which will look through my data set and find out where the issues lie (because some data sets run without the above error and others have problems)?

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  • How to get Host OS (operating system) parameter of ZIP archive in C#

    - by bao
    Look. I have ZIP archives prepared in different os'es: mac, linux, windows. In windows file names encoded in DOS CP866, mac & linux in UTF-8. I need to know (in code) in which os zip file was prepared to decode file names correctly. There is a Host OS paramterer in "Central directory structure" of zip file (look http://www.fileformat.info/format/zip/corion.htm ). How to get 0005h 1 byte Host OS parameter in C#?

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  • Fast exchange of data between unmanaged code and managed code

    - by vizcaynot
    Hello: Without using p/invoke, from a C++/CLI I have succeeded in integrating various methods of a DLL library from a third party built in C. One of these methods retrieves information from a database and stores it in different structures. The C++/CLI program I wrote reads those structures and stores them in a List<, which is then returned to the corresponding reading and use of an application programmed completely in C#. I understand that the double handling of data (first, filling in several structures and then, filling all of these structures into a list<) may generate an unnecessary overload, at which point I wish C++/CLI had the keyword "yield". Depending on the above scenario, do you have recommendations to avoid or reduce this overload? Thanks.

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  • Indexing datetime in MySQL

    - by User1
    What is the best way to index a datetime in MySQL? Which method is faster: Store the datetime as a double (via unix timestamp) Store the datetime as a datetime The application generating the timestamp data can output either format. Unfortunately, datetime will be a key for this particular data structure so speed will matter. Also, is it possible to make an index on an expression? For example, index on UNIX_TIMESTAMP(mydate) where mydate is a field in a table and UNIX_TIMESTAMP is a mysql function. I know that Postgres can do it. I'm thinking there must be a way in mysql as well.

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  • Facebook user_id as MongoDB BSON ObjectId?

    - by MattDiPasquale
    I'm rebuilding Lovers on Facebook with Sinatra & Redis. I like Redis because it doesn't have the long (12-byte) BSON ObjectIds and I am storing sets of Facebook user_ids for each user. The sets are requests_sent, requests_received, & relationships, and they all contain Facebook user ids. I'm thinking of switching to MongoDB because I want to use it's geospatial indexing. If I do, I'd want to use the FB user ids as the _id field because I want the sets to be small and I want the JSON responses to be small. But, is the BSON ObjectId better (more efficient for MongoDB) to use than just an integer (fb user_id)?

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  • is it posible to upload directly to remote server using SFTP on ASP.net MVC

    - by DucDigital
    Hi! I am currently develope something using asp.net MVC, im still quite not experience with it so please help me out. I have a form for user to upload Video. The current ideal concept to upload to remote server is to Upload it to to the current server, then use FTP to push it to a remote server. For me, this is not quite fast since you have to upload to current server (Time x1) and then the current server push to new server (Time x2) so it's double the time. So my idea is to make user upload it to the current server, and WHILE user is uploading, the current server add the file to DB and also send the file to the remote server at the same time using SFTP... is it posible and are there any security hole in this concept? Thank you very much

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  • how do i round/trucate a number without using methods like math.round or %3f?

    - by user2923875
    So far I need to round a number that I inputted and get it to 3 decimal places without those methods. if(number !=(int)number){ number*=1000; number=(int)number; number=(double)number; number/=1000; System.out.println("-"+ number); } if(number ==(int)number){ System.out.println("-"+ number + "00"); } With that above, it will work for any input except the ones with 2 decimal places, like 12.34 . How do I make it work if i type 12.34 and displays 12.340?

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  • Object to Network serialization - with an existing protocol

    - by cpf
    I'm writing a client for a server program written in C++. As is not unusual, all the networking protocol is in a format where packets can be easily memcopied into/out of a C++ structure (1 byte packet code, then different arrangements per packet type). I could do the same thing in C#, but is there an easier way, especially considering lots of the data is fixed-length char arrays that I want to play with as strings? Or should I just suck it up and convert types as needed? I've looked at using the ISerializable interface, but it doesnt look as low level as is required.

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  • How to handle large table in MySQL ?

    - by Frantz Miccoli
    I've a database used to store items and properties about these items. The number of properties is extensible, thus there is a join table to store each property associated to an item value. CREATE TABLE `item_property` ( `property_id` int(11) NOT NULL, `item_id` int(11) NOT NULL, `value` double NOT NULL, PRIMARY KEY (`property_id`,`item_id`), KEY `item_id` (`item_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; This database has two goals : storing (which has first priority and has to be very quick, I would like to perform many inserts (hundreds) in few seconds), retrieving data (selects using item_id and property_id) (this is a second priority, it can be slower but not too much because this would ruin my usage of the DB). Currently this table hosts 1.6 billions entries and a simple count can take up to 2 minutes... Inserting isn't fast enough to be usable. I'm using Zend_Db to access my data and would really be happy if you don't suggest me to develop any php side part. Thanks for your advices !

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  • PDF coming as text on browser

    - by spt3210
    I am trying to display a PDF from database (byte[]) to user. I am using code below to render PDF. It is giving me PDF as binary text as shown below. Instead of open in PDF application it is rendering PDF as text. Response.Buffer = true; Response.Charset = ""; Response.Cache.SetCacheability(HttpCacheability.NoCache); //Response.AddHeader("Content-Length", fileToDownload.Length.ToString()); //Response.AddHeader("Content-Disposition", "inline; name=RemoteUserGuide.pdf"); Response.AppendHeader("content-length", fileToDownload.Length.ToString()); Response.ContentType = "application/pdf"; Response.BinaryWrite(fileToDownload); Response.Flush(); ////Response.Close(); Response.End(); Any Ideas?

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  • Is there a Java Descriptor like thing in .Net?

    - by Sun Liwen
    I'm working on a static analysis tool for .NET assembly. In Java, there is a Descriptor which can be used to represent method or field in a string with specified grammar. for field: double d[][][]; will be [[[D It's useful especially when doing bytecode analysis. Coz it's easy to describe. If there a similar thing in .NET CLR? Or is there a better way to achieve this? Thanks!

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  • Constructor Type Coercion in C++

    - by Robert Mason
    Take the following class: class mytype { double num; public: mytype(int a) { num = sqrt(a); } void print() { cout << num; } } Say there is a method which takes a mytype: void foo(mytype a) { a.print(); } Is it legal c++ (or is there a way to implement this) to call foo(4), which would (in theory) output 2? From what I can glean you can overload type casts from a user defined class, but not to. Can constructor do this in a standards-compliant manner (assuming, of course, the constructor is not explicit). Hopefully there is a way to in the end have this legal: int a; cin >> a; foo(a); Note: this is quite obviously not the actual issue, but just an example for posting purposes. I can't just overload the function because of inheritance and other program-specific issues.

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  • What is an alternative to ADO.NET, but elegant way in C# to read Excel files

    - by Khnle
    ADO.NET just fails miserably when it's used to read Excel files where a column contains mixed data types. It appears that it tries to determine the data type of a column, and then assume the rest of the entire column is of the same data type. Here are some backgrounds: http://stackoverflow.com/questions/2968111/how-to-prevent-ado-net-from-altering-double-values-when-it-reads-from-excel-files http://blog.lab49.com/archives/196 What is an alternative approach that doesn't require automation, Excel to be co-installed, is simple (since the input excel file will only have one worksheet in each file).

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  • How to map a property for HQL usage only (in Hibernate)?

    - by ManBugra
    i have a table like this one: id | name | score mapped to a POJO via XML with Hibernate. The score column i only need in oder by - clauses in HQL. The value for the score column is calculated by an algorithm and updated every 24 hours via SQL batch process (JDBC). So i dont wanna pollute my POJO with properties i dont need at runtime. For a single column that may be not a problem, but i have several different score columns. Is there a way to map a property for HQL use only? For example like this: <property name="score" type="double" ignore="true"/> so that i still can do this: from Pojo p order by p.score but my POJO implementation can look like this: public class Pojo { private long id; private String name; // ... } No Setter for score provided or property added to implementation. using the latest Hibernate version for Java.

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  • KeybListener problem

    - by rgksugan
    In my apllication i am using a jpanel in which i want to add a key listener. I did it. But it doesnot work. Is it because i am using a swingworker to update the contents of the panel every second. Here is my code to update the panel RenderedImage image = ImageIO.read(new ByteArrayInputStream((byte[]) get())); Graphics graphics = remote.rdpanel.getGraphics(); if (graphics != null) { Image readyImage = new ImageIcon(UtilityFunctions.convertRenderedImage(image)).getImage(); graphics.drawImage(readyImage, 0, 0, remote.rdpanel.getWidth(), remote.rdpanel.getHeight(), null); }

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  • Multi-threaded downloader in C# question

    - by blez
    Currently I have multi-threaded downloader class that uses HttpWebRequest/Response. All works fine, it's super fast, BUT.. the problem is that the data needs to be streamed while it's downloading to another app. That means that it must be streamed in the right order, the first chunk first, and then the next in the queue. Currently my downloader class is sync and Download() returns byte[]. In my async multi-threaded class I make for example, list with 4 empty elements (for slots) and I pass each index of the slot to each thread using the Download() function. That simulates synchronization, but that's not what I need. How should I do the queue thing, to make sure the data is streamed as soon as the first chunk start downloading.

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  • SQLite SQLite column can't be updated to any value but zero (real type)

    - by user1065320
    Hi I'm trying to create a three fields table (date,text,real), I can insert and update the first two fields but can't set or update the last one. createSQL = @"CREATE TABLE IF NOT EXISTS ACTIVITIES (MYDATE DATETIME PRIMARY KEY, ACTIVITY TEXT , LENGTH REAL);"; try to insert char *update = "INSERT OR REPLACE INTO ACTIVITIES (MYDATE, ACTIVITY , LENGTH) VALUES (?, ? ,?);"; sqlite3_stmt *stmt; if (sqlite3_prepare_v2(database, update , -1, &stmt, nil) == SQLITE_OK) { sqlite3_bind_double(stmt, 1, valueToWrite); sqlite3_bind_text(stmt, 2, [task UTF8String], -1, NULL); sqlite3_bind_double(stmt, 3, 1.5); } if (sqlite3_step(stmt) != SQLITE_DONE) { NSAssert1(0, @"Error updating table: %s", errorMsg); } sqlite3_finalize(stmt); sqlite3_close(database); The first two values are updated but the last one remains 0 even if I'm writing a value like 1.5 or put a double variable with a different value Thanks

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  • C# string equality operator returns false, but I'm pretty sure it should be true... What?!

    - by Daniel Schaffer
    I'm trying to write a unit test for a piece of code that generates a large amount of text. I've run into an issue where the "expected" and "actual" strings appear to be equal, but Assert.AreEqual throws, and both the equality operator and Equals() return false. The result of GetHashCode() is different for both values as well. However, putting both strings into text files and comparing with DiffMerge tells me they're the same. Additionally, using Encoding.ASCII.GetBytes() on both values and then using SequenceEquals to compare the resulting byte arrays returns true. The values are 34KB each, so I'll hold off putting them here for now. Any ideas? I'm completely stumped.

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  • Adjusting for compass wrap around in a navigation application

    - by chris12892
    I have a application where I am guiding a vehicle on compass headings and I am having an issue when the vehicle is crossing from 360 degrees to 0 degrees. In this case, there are no smarts in the control loop to compute that the nearest way to turn to follow a heading. For example, if the vehicle is instructed to follow a heading of 360 degrees, it will inevitably drifts a few degrees to ether side. If it drifts over to 0+ degrees, the control loop will go nuts and try to steer the vehicle all the way around to get it to 360 degrees again. Is there a graceful way to deal with this? The way the navigate function is written, I use an external PID controller class and I calculate the heading like this: lock (steering) { if (!Engaged) { return; } double mv = 90 + Trim + pidController.CalculateCorrection(flyHeading, currentHeading); steering.Degree = mv; } Thanks!

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  • Quick way to do data lookup in PHP

    - by Ghostrider
    I have a data table with 600,000 records that is around 25 megabytes large. It is indexed by a 4 byte key. Is there a way to find a row in such dataset quickly with PHP without resorting to MySQL? The website in question is mostly static with minor PHP code and no database dependencies and therefore fast. I would like to add this data without having to use MySQL if possible. In C++ I would memory map the file and do a binary search in it. Is there a way to do something similar in PHP?

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  • How can I get Perl to detect the bad UTF-8 sequences?

    - by gorilla
    I'm running Perl 5.10.0 and Postgres 8.4.3, and strings into a database, which is behind a DBIx::Class. These strings should be in UTF-8, and therefore my database is running in UTF-8. Unfortunatly some of these strings are bad, containing malformed UTF-8, so when I run it I'm getting an exception DBI Exception: DBD::Pg::st execute failed: ERROR: invalid byte sequence for encoding "UTF8": 0xb5 I thought that I could simply ignore the invalid ones, and worry about the malformed UTF-8 later, so using this code, it should flag and ignore the bad titles. if(not utf8::valid($title)){ $title="Invalid UTF-8"; } $data->title($title); $data->update(); However Perl seems to think that the strings are valid, but it still throws the exceptions. How can I get Perl to detect the bad UTF-8?

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  • Me As Child Type In General Function

    - by Steven
    I have a MustInherit Parent class with two Child classes which Inherit from the Parent. How can I use (or Cast) Me in a Parent function as the the child type of that instance? EDIT: My actual goal is to be able to serialize (BinaryFormatter.Serialize(Stream, Object)) either of my child classes. However, "repeating the code" in each child "seems" wrong. EDIT2: This is my Serialize function. Where should I implement this function? Copying and pasting to each child doesn't seem right, but casting the parent to a child doesn't seem right either. Public Function Serialize() As Byte() Dim bFmt As New BinaryFormatter() Dim mStr As New MemoryStream() bFmt.Serialize(mStr, Me) Return mStr.ToArray() End Function

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  • Regular Expression to return the contents of a HTML tag received as a string of text

    - by Nathan Hernandez
    I have a string in my code that I receive that contains some html tags. It is not part of the HTML page being displayed so I cannot grab the html tag contents using the DOM (i.e. document.getElementById('tag id').firstChild.data); So, for example within the string of text would appear a tag like this: 12 My question is how would I use a regular expression to access the '12' numeric digit in this example? This quantity could be any number of digits (i.e. it is not always a double digit). I have tried some regular expressions, but always end up getting the full span tag returned along with the contents. I only want the '12' in the example above, not the surrounding tag. The id of the tags will always be 'myQty' in the string of text I receive. Thanks in advance for any help!

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