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  • Converting Bit Field to int

    - by shaharg
    Hi, I have bit field declared this way: typedef struct morder { unsigned int targetRegister : 3; unsigned int targetMethodOfAddressing : 3; unsigned int originRegister : 3; unsigned int originMethodOfAddressing : 3; unsigned int oCode : 4; } bitset; I also have int array, and i want to get int value from this array, that represents the actual value of this bit field (which is actually some kind of machine word that i have the parts of it, and i want the int representation of the whole word). Thanks a lot.

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  • Not-quite-JSON string deserialization in Python

    - by cpharmston
    I get the following text as a string from an XML-based REST API 'd':4 'ca':5 'sen':1 'diann':2,6,8 'feinstein':3,7,9 that I'm looking to deserialize into a pretty little Python dictionary: { 'd': [4], 'ca': [5], 'sen': [1], 'diann': [2, 6, 8], 'feinstein': [3, 7, 9] } I'm hoping to avoid using regular expressions or heavy string manipulation, as this format isn't documented and may change. The best I've been able to come up with: members = {} for m in elem.text.split(' '): m = m.split(':') members[m[0].replace("'", '')] = map(int, m[1].split(',')) return members Obviously a terrible approach, but it works, and that's better than anything else I've got right now. Any suggestions on better approaches?

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  • Setting Mercurial's execute bit on Windows

    - by Joe
    I work on a Mercurial repository that is checked out onto an Unix filesystem such as ext3 on some machines, and FAT32 on others. In Subversion, I can set the svn:executable property to control whether a file should be marked executable when checked out on a platform that supports such a bit. I can do this regardless of the platform I'm running SVN on or the filesystem containing my working copy. In Mercurial, I can chmod +x to get the same effect if the clone is on a Unix filesystem. But how can I set (or remove) the executable bit on a file on a FAT filesystem?

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  • 0xDEADBEEF equivalent for 64-bit development?

    - by Peter Mortensen
    For C++ development for 32-bit systems (be it Linux, Mac OS or Windows, PowerPC or x86) I have initialised pointers that would otherwise be undefined (e.g. they can not immediately get a proper value) like so: int *pInt = reinterpret_cast<int *>(0xDEADBEEF); (To save typing and being DRY the right-hand side would normally be in a constant, e.g. BAD_PTR.) If pInt is dereferenced before it gets a proper value then it will crash immediately on most systems (instead of crashing much later when some memory is overwritten or going into a very long loop). Of course the behavior is dependent on the underlying hardware (getting a 4 byte integer from the odd address 0xDEADBEEF from a user process may be perfectly valid), but the crashing has been 100% reliable for all the systems I have developed for so far (Mac OS 68xxx, Mac OS PowerPC, Linux Redhat Pentium, Windows GUI Pentium, Windows console Pentium). For instance on PowerPC it is illegal (bus fault) to fetch a 4 byte integer from an odd address. What is a good value for this on 64-bit systems?

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  • Issue with RegConnectRegistry connecting to 64 bit machines

    - by RA
    I'm seeing a weird thing when connecting to the performance registry on 64 bit editions of Windows. The whole program stalls and callstacks becomes unreadable. After a long timeout, the connection attempts aborts and everything goes back to normal. The only solution is to make sure that only one thread at the time queries the remote registry, unless the remote machine is a 32 bit Windows XP, 2003, 2000 , then you can use as many threads as you like. Have anyone a technical explanation why this might be happening ? I've spent 2-3 days searching the web without coming up with anything. Here is a test program, run it first with one thread (connecting to a 64 bit Windows), then remove the comment in tmain and run it with 4 threads. Running it with one thread works as expected, running with 4, returns ERROR_BUSY (dwRet == 170) after stalling for a while. Remember to set a remote machine correctly in RegConnectRegistry before running the program. #define TOTALBYTES 8192 #define BYTEINCREMENT 4096 void PerfmonThread(void *pData) { DWORD BufferSize = TOTALBYTES; DWORD cbData; DWORD dwRet; PPERF_DATA_BLOCK PerfData = (PPERF_DATA_BLOCK) malloc( BufferSize ); cbData = BufferSize; printf("\nRetrieving the data..."); HKEY hKey; DWORD dwAccessRet = RegConnectRegistry(L"REMOTE_MACHINE",HKEY_PERFORMANCE_DATA,&hKey); dwRet = RegQueryValueEx( hKey,L"global",NULL,NULL,(LPBYTE) PerfData, &cbData ); while( dwRet == ERROR_MORE_DATA ) { // Get a buffer that is big enough. BufferSize += BYTEINCREMENT; PerfData = (PPERF_DATA_BLOCK) realloc( PerfData, BufferSize ); cbData = BufferSize; printf("."); dwRet = RegQueryValueEx( hKey,L"global",NULL,NULL,(LPBYTE) PerfData,&cbData ); } if( dwRet == ERROR_SUCCESS ) printf("\n\nFinal buffer size is %d\n", BufferSize); else printf("\nRegQueryValueEx failed (%d)\n", dwRet); RegCloseKey(hKey); } int _tmain(int argc, _TCHAR* argv[]) { _beginthread(PerfmonThread,0,NULL); /* _beginthread(PerfmonThread,0,NULL); _beginthread(PerfmonThread,0,NULL); _beginthread(PerfmonThread,0,NULL); */ while(1) { Sleep(2000); } }

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  • java.util.BitSet -- set() doesn't work as expected

    - by dwhsix
    Am I missing something painfully obvious? Or does just nobody in the world actually use java.util.BitSet? The following test fails: @Test public void testBitSet() throws Exception { BitSet b = new BitSet(); b.set(0, true); b.set(1, false); assertEquals(2, b.length()); } It's really unclear to me why I don't end up with a BitSet of length 2 and the value 10. I peeked at the source for java.util.BitSet, and on casual inspection it seems to fail to make sufficient distinction between a bit that's been set false and a bit that has never been set to any value... (Note that explicitly setting the size of the BitSet in the constructor has no effect, e.g.: BitSet b = new BitSet(2);

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  • Application leaking Strings?

    - by Jörg B.
    My .net application does some heavy string loading/manipulation and unfortunately the memory consumption keeps rising and rising and when looking at it with a profiler I see alot of unreleased string instances. Now at one point of time or another I do need all objects t hat do have these string fields, but once done, I could get rid of e.g. the half of it and I Dispose() and set the instances to null, but the Garbage Collector does not to pick that up.. they remain in memory (even after half an hour after disposing etc). Now how do I get properly rid of unneeded strings/object instances in order to release them? They are nowhere referenced anymore (afaik) but e.g. aspose's memory profiler says their distance to the gc's root is '3'?

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  • C++ iostream not setting eof bit even if gcount returns 0

    - by raph.amiard
    Hi I'm developping an application under windows, and i'm using fstreams to read and write to the file. I'm writing with fstream opened like this : fs.open(this->filename.c_str(), std::ios::in|std::ios::out|std::ios::binary); and writing with this command fs.write(reinterpret_cast<char*>(&e.element), sizeof(T)); closing the file after each write with fs.close() Reading with ifstream opened like this : is.open(filename, std::ios::in); and reading with this command : is.read(reinterpret_cast<char*>(&e.element), sizeof(T)); The write is going fine. However, i read in a loop this way : while(!is.eof()) { is.read(reinterpret_cast<char*>(&e.element), sizeof(T)); } and the program keeps reading, even though the end of file should be reached. istellg pos is 0, and gcount is equal to 0 too, but the fail bit and eof bit are both ok. I'm running crazy over this, need some help ...

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  • [C] converting Bit Field to int

    - by shaharg
    Hi, I have bit field declared this way: typedef struct morder { unsigned int targetRegister : 3; unsigned int targetMethodOfAddressing : 3; unsigned int originRegister : 3; unsigned int originMethodOfAddressing : 3; unsigned int oCode : 4; } bitset; I also have int array, and i want to get int value from this array, that represents the actual value of this bit field (which is actually some kind of machine word that i have the parts of it, and i want the int representation of the whole word). Thanks a lot.

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  • bitshift large strings for encoding QR Codes

    - by icekreaman
    As an example, suppose a QR Code data stream contains 55 data words (each one byte in length) and 15 error correction words (again one byte). The data stream begins with a 12 bit header and ends with four 0 bits. So, 12 + 4 bits of header/footer and 15 bytes of error correction, leaves me 53 bytes to hold 53 alphanumeric characters. The 53 bytes of data and 15 bytes of ec are supplied in a string of length 68 (str68). The problem seems simple enough - concatenate 2 bytes of (right-shifted) header data with str68 and then left shift the entire 70 bytes by 4 bits. This is the first time in many years of programming that I have ever needed to do something like this, I am a c and bit shifting noob, so please be gentle... I have done a little investigation and so far have not been able to figure out how to bitshift 70 bytes of data; any help would be greatly appreciated. Larger QR codes can hold 2000 bytes of data...

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  • 64 bit COM(ActiveX) server

    - by Velja Radenkovic
    Hello, I have activex server exe that was building and registering fine on 32bit OS. I wanted to make 64 bit version of that exe by upgrading project to Visual Studio 2010 and changing platform to X64 which apparently doesn't work. Application itself works but I don't see it registered after running That.exe /RegServer I would appreciate any usable advice on migrating activex from 32 to x64. Code that is processing /RegServer param is below: if(lstrcmpi(lpszToken, _T("RegServer")) == 0) { _Module.UpdateRegistryFromResource(IDR_OUTDISKSARG, TRUE); nRet = _Module.RegisterServer(TRUE); bRun = false; break; } 32 bit activex is unuable for me since I have to load it in x64 .NET process.

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  • Finding shared list IDs in a MySQL table using bitwise operands

    - by landons
    I want to find items in common from the "following_list" column in a table of users: +----+--------------------+-------------------------------------+ | id | name | following_list | +----+--------------------+-------------------------------------+ | 9 | User 1 | 26,6,12,10,21,24,19,16 | | 10 | User 2 | 21,24 | | 12 | User 3 | 9,20,21,26,30 | | 16 | User 4 | 6,52,9,10 | | 19 | User 5 | 9,10,6,24 | | 21 | User 6 | 9,10,6,12 | | 24 | User 7 | 9,10,6 | | 46 | User 8 | 45 | | 52 | User 9 | 10,12,16,21,19,20,18,17,23,25,24,22 | +----+--------------------+-------------------------------------+ I was hoping to be able to sort by the number of matches for a given user id. For example, I want to match all users except #9 against #9 to see which of the IDs in the "following_list" column they have in common. I found a way of doing this through the "SET" datatype and some bit trickery: http://dev.mysql.com/tech-resources/articles/mysql-set-datatype.html#bits However, I need to do this on an arbitrary list of IDs. I was hoping this could be done entirely through the database, but this is a little out of my league. Any bit gurus out there? Thanks, Landon

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  • Most efficient way to remove special characters from string

    - by ObiWanKenobi
    I want to remove all special characters from a string. Allowed characters are A-Z (uppercase or lowercase), numbers (0-9), underscore (_), or the dot sign (.). I have the following, it works but I suspect (I know!) it's not very efficient: public static string RemoveSpecialCharacters(string str) { StringBuilder sb = new StringBuilder(); for (int i = 0; i < str.Length; i++) { if ((str[i] >= '0' && str[i] <= '9') || (str[i] >= 'A' && str[i] <= 'z' || (str[i] == '.' || str[i] == '_'))) sb.Append(str[i]); } return sb.ToString(); } What is the most efficient way to do this? What would a regular expression look like, and how does it compare with normal string manipulation? The strings that will be cleaned will be rather short, usually between 10 and 30 characters in length.

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  • How to manually (bitwise) perform (float)x? (homework)

    - by Silver
    Now, here is the function header of the function I'm supposed to implement: /* * float_from_int - Return bit-level equivalent of expression (float) x * Result is returned as unsigned int, but * it is to be interpreted as the bit-level representation of a * single-precision floating point values. * Legal ops: Any integer/unsigned operations incl. ||, &&. also if, while * Max ops: 30 * Rating: 4 */ unsigned float_from_int(int x) { ... } We aren't allowed to do float operations, or any kind of casting. Now I tried to implement the first algorithm given at this site: http://locklessinc.com/articles/i2f/ Here's my code: unsigned float_from_int(int x) { // grab sign bit int xIsNegative = 0; int absValOfX = x; if(x < 0){ xIsNegative = 1; absValOfX = -x; } // zero case if(x == 0){ return 0; } //int shiftsNeeded = 0; /*while(){ shiftsNeeded++; }*/ unsigned I2F_MAX_BITS = 15; unsigned I2F_MAX_INPUT = ((1 << I2F_MAX_BITS) - 1); unsigned I2F_SHIFT = (24 - I2F_MAX_BITS); unsigned result, i, exponent, fraction; if ((absValOfX & I2F_MAX_INPUT) == 0) result = 0; else { exponent = 126 + I2F_MAX_BITS; fraction = (absValOfX & I2F_MAX_INPUT) << I2F_SHIFT; i = 0; while(i < I2F_MAX_BITS) { if (fraction & 0x800000) break; else { fraction = fraction << 1; exponent = exponent - 1; } i++; } result = (xIsNegative << 31) | exponent << 23 | (fraction & 0x7fffff); } return result; } But it didn't work (see test error below): Test float_from_int(-2147483648[0x80000000]) failed... ...Gives 0[0x0]. Should be -822083584[0xcf000000] 4 4 0 float_times_four I don't know where to go from here. How should I go about parsing the float from this int?

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  • app.config and 64-bit machines

    - by Dale Lutes
    I have an app that works fine on 32-bit systems, but fails on XP 64 bit systems. I've tracked it down to the connection string defined in my app.config thus: <connectionStrings> <clear/> <add name="IFDSConnectionString" connectionString="Data Source=fdsdata;Initial Catalog=IFDS; Trusted_Connection=true;Connect Timeout=0" providerName="System.Data.SqlClient" /> </connectionStrings> When I try to reference it in code, I find that the ConfigurationManager.ConnectionStrings collection only contains the LocalSqlServer connection string from the machine.config file and not my custom string. Another oddity is that it works fine when I run the app out of Visual Studio. It is only when I run out of the release folder that the connection string does not get defined. The application's .exe.config file is there in the release folder along with the .exe file and is up to date.

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  • Compiling zlib for 64 bit on windows

    - by Allan Hollenberg
    I am currently working on a cross-platform game for Mac OSX and Windows and I'm having some issues with the ZLib library on Windows 64 bit. My game is focussed on a 64 bit architecture and I am unable to get ZLib to work along with it. When I compile ZLib itself (through make all64 at the source directory of ZLib) it shows no issues but when I want to use it I get a error saying '/usr/local/lib/libz.a(gzread.o):gzread.c:(.text+0x28e): undefined reference to `__errno'' I have included errno.h before I include zlib.h in my project but that doesn't seem to matter. I am compiling my app through the cygwin64 terminal and using the x86_64-w64-mingw32-g++ command, I am also linking directly against the lib64 version (if I remove that it compiles correctly but crashes on running due to it having a x86 lib)

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  • regular expression for bit strings with even number of 1s

    - by equilibrium
    Let L= { w in (0+1)* | w has even number of 1s}, i.e. L is the set of all bit strings with even number of 1s. Which one of the regular expressions below represents L? A) (0*10*1)* B) 0*(10*10*)* C) 0*(10*1)* 0* D) 0*1(10*1)* 10* According to me option D is never correct because it does not represent the bit string with zero 1s. But what about the other options? We are concerned about the number of 1s(even or not) not the number of zeros doesn't matter. Then which is the correct option and why?

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  • Efficient mapping for a particular finite integer set

    - by R..
    I'm looking for a small, fast (in both directions) bijective mapping between the following list of integers and a subset of the range 0-127: 0x200C, 0x200D, 0x200E, 0x200F, 0x2013, 0x2014, 0x2015, 0x2017, 0x2018, 0x2019, 0x201A, 0x201C, 0x201D, 0x201E, 0x2020, 0x2021, 0x2022, 0x2026, 0x2030, 0x2039, 0x203A, 0x20AA, 0x20AB, 0x20AC, 0x20AF, 0x2116, 0x2122 One obvious solution is: y = x>>2 & 0x40 | x & 0x3f; x = 0x2000 | y<<2 & 0x100 | y & 0x3f; Edit: I was missing some of the values, particularly 0x20Ax, which don't work with the above. Another obvious solution is a lookup table, but without making it unnecessarily large, a lookup table would require some bit rearrangement anyway and I suspect the whole task can be better accomplished with simple bit rearrangement. For the curious, those magic numbers are the only "large" Unicode codepoints that appear in legacy ISO-8859 and Windows codepages.

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  • Dividing n-bit binary integers

    - by Julian
    Was wondering if anyone could help me with creating a pseudocode for how to go about dividing n-bit binary integers. Here is what I'm thinking could possibly work right now, could someone correct this if I'm wrong: divide (x,y) if x=0: return (0,0) //(quotient, remainder) (q,r) = divide(floor(x/2), y) q=2q, r=2r if x is odd: r = r+1 if r >= y: r = r-y, q = q+1 return (q,r) Would you guys say that this general pseudocode algorithm would accomplish the intended task of dividing n-bit numbers or am I missing something in my psuedocode before I start coding up something that's wrong?

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  • How to combine two 32-bit integers into one 64-bit integer?

    - by Bei337
    I have a count register, which is made up of two 32-bit unsigned integers, one for the higher 32 bits of the value (most significant word), and other for the lower 32 bits of the value (least significant word). What is the best way in C to combine these two 32-bit unsigned integers and then display as a large number? In specific: leastSignificantWord = 4294967295; //2^32-1 printf("Counter: %u%u", mostSignificantWord,leastSignificantWord); This would print fine. When the number is incremented to 4294967296, I have it so the leastSignificantWord wipes to 0, and mostSignificantWord (0 initially) is now 1. The whole counter should now read 4294967296, but right now it just reads 10, because I'm just concatenating 1 from mostSignificantWord and 0 from leastSignificantWord. How should I make it display 4294967296 instead of 10?

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  • binary number comparison

    - by EquinoX
    If I have a 32 bit two's complement number and I want to know what is the easiest way to know of two numbers are equal... what would be the fastest bitwise operator to know this? I know xor'ing both numbers and check if the results are zero works well... any other one's? how about if a number is greater than 0?? I can check the 31'st bit to see if it's greater or equal to 0..but how about bgtz?

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