Search Results

Search found 11826 results on 474 pages for 'parallel port'.

Page 79/474 | < Previous Page | 75 76 77 78 79 80 81 82 83 84 85 86  | Next Page >

  • What is the best way to scan for COM ports in C#?

    - by Jim Fell
    Does C# provide an effective means of scanning the available COM ports? I would like to have a dropdown list in my application wherein the user can select one of the detected COM ports. Creating and populating the dropdown list is not a problem. I just need to know how to scan for the available COM ports using C#. I am using Microsoft Visual C# 2008 Express Edition. Thanks.

    Read the article

  • How to use SerialPort SerialDataReceived help

    - by devnet247
    Hi Not sure how to handle SerialPort DataReceived. Scenario I have an application that communicate with a device and this device returns a status .This happens in different stages EG public enum ActionState { Started, InProgress, Completed etc... } Now if I were to use the DataReceivedEventHandler how can I tell what Method is executing? eg Action1 or Action2 etc...? I also want to include some sort of timeout when getting back stuff from device. Any example or advice? public ActionState Action1 { serialPort.write(myData); string result=serialPort.ReadExisting()); //convertTo ActionState and return return ConvertToActionState(result); } public ActionState Action2 { serialPort.write(myData); string result=serialPort.ReadExisting()); //convertTo ActionState and return return ConvertToActionState(result); } private void port_DataReceived(object sender, SerialDataReceivedEventArgs e) { //How can I use this to detect which method is firing and set the actionState Enum accordingly? } private ActionState(string result) { if(result==1) return ActionState.Started; else if (result==2) return ActionState.Completed etc... }

    Read the article

  • Return data from subroutine while the subroutine is still processing

    - by Perl QuestionAsker
    Is there any way to have a subroutine send data back while still processing? For instance (this example used simply to illustrate) - a subroutine reads a file. While it is reading through the file, if some condition is met, then "return" that line and keep processing. I know there are those that will answer - why would you want to do that? and why don't you just ...?, but I really would like to know if this is possible. Thank you so much in advance.

    Read the article

  • How can I connect to a mail server using SMTP over SSL using Python?

    - by jakecar
    Hello, So I have been having a hard time sending email from my school's email address. It is SSL and I could only find this code online by Matt Butcher that works with SSL: import smtplib, socket version = "1.00" all = ['SMTPSSLException', 'SMTP_SSL'] SSMTP_PORT = 465 class SMTPSSLException(smtplib.SMTPException): """Base class for exceptions resulting from SSL negotiation.""" class SMTP_SSL (smtplib.SMTP): """This class provides SSL access to an SMTP server. SMTP over SSL typical listens on port 465. Unlike StartTLS, SMTP over SSL makes an SSL connection before doing a helo/ehlo. All transactions, then, are done over an encrypted channel. This class is a simple subclass of the smtplib.SMTP class that comes with Python. It overrides the connect() method to use an SSL socket, and it overrides the starttles() function to throw an error (you can't do starttls within an SSL session). """ certfile = None keyfile = None def __init__(self, host='', port=0, local_hostname=None, keyfile=None, certfile=None): """Initialize a new SSL SMTP object. If specified, `host' is the name of the remote host to which this object will connect. If specified, `port' specifies the port (on `host') to which this object will connect. `local_hostname' is the name of the localhost. By default, the value of socket.getfqdn() is used. An SMTPConnectError is raised if the SMTP host does not respond correctly. An SMTPSSLError is raised if SSL negotiation fails. Warning: This object uses socket.ssl(), which does not do client-side verification of the server's cert. """ self.certfile = certfile self.keyfile = keyfile smtplib.SMTP.__init__(self, host, port, local_hostname) def connect(self, host='localhost', port=0): """Connect to an SMTP server using SSL. `host' is localhost by default. Port will be set to 465 (the default SSL SMTP port) if no port is specified. If the host name ends with a colon (`:') followed by a number, that suffix will be stripped off and the number interpreted as the port number to use. This will override the `port' parameter. Note: This method is automatically invoked by __init__, if a host is specified during instantiation. """ # MB: Most of this (Except for the socket connection code) is from # the SMTP.connect() method. I changed only the bare minimum for the # sake of compatibility. if not port and (host.find(':') == host.rfind(':')): i = host.rfind(':') if i >= 0: host, port = host[:i], host[i+1:] try: port = int(port) except ValueError: raise socket.error, "nonnumeric port" if not port: port = SSMTP_PORT if self.debuglevel > 0: print>>stderr, 'connect:', (host, port) msg = "getaddrinfo returns an empty list" self.sock = None for res in socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM): af, socktype, proto, canonname, sa = res try: self.sock = socket.socket(af, socktype, proto) if self.debuglevel > 0: print>>stderr, 'connect:', (host, port) self.sock.connect(sa) # MB: Make the SSL connection. sslobj = socket.ssl(self.sock, self.keyfile, self.certfile) except socket.error, msg: if self.debuglevel > 0: print>>stderr, 'connect fail:', (host, port) if self.sock: self.sock.close() self.sock = None continue break if not self.sock: raise socket.error, msg # MB: Now set up fake socket and fake file classes. # Thanks to the design of smtplib, this is all we need to do # to get SSL working with all other methods. self.sock = smtplib.SSLFakeSocket(self.sock, sslobj) self.file = smtplib.SSLFakeFile(sslobj); (code, msg) = self.getreply() if self.debuglevel > 0: print>>stderr, "connect:", msg return (code, msg) def setkeyfile(self, keyfile): """Set the absolute path to a file containing a private key. This method will only be effective if it is called before connect(). This key will be used to make the SSL connection.""" self.keyfile = keyfile def setcertfile(self, certfile): """Set the absolute path to a file containing a x.509 certificate. This method will only be effective if it is called before connect(). This certificate will be used to make the SSL connection.""" self.certfile = certfile def starttls(): """Raises an exception. You cannot do StartTLS inside of an ssl session. Calling starttls() will return an SMTPSSLException""" raise SMTPSSLException, "Cannot perform StartTLS within SSL session." And then my code: import ssmtplib conn = ssmtplib.SMTP_SSL('HOST') conn.login('USERNAME','PW') conn.ehlo() conn.sendmail('FROM_EMAIL', 'TO_EMAIL', "MESSAGE") conn.close() And got this error: /Users/Jake/Desktop/Beth's Program/ssmtplib.py:116: DeprecationWarning: socket.ssl() is deprecated. Use ssl.wrap_socket() instead. sslobj = socket.ssl(self.sock, self.keyfile, self.certfile) Traceback (most recent call last): File "emailer.py", line 5, in conn = ssmtplib.SMTP_SSL('HOST') File "/Users/Jake/Desktop/Beth's Program/ssmtplib.py", line 79, in init smtplib.SMTP.init(self, host, port, local_hostname) File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/smtplib.py", line 239, in init (code, msg) = self.connect(host, port) File "/Users/Jake/Desktop/Beth's Program/ssmtplib.py", line 131, in connect self.sock = smtplib.SSLFakeSocket(self.sock, sslobj) AttributeError: 'module' object has no attribute 'SSLFakeSocket' Thank you!

    Read the article

  • Strategies to use Database Sequences?

    - by Bruno Brant
    Hello all, I have a high-end architecture which receives many requests every second (in fact, it can receive many requests every millisecond). The architecture is designed so that some controls rely on a certain unique id assigned to each request. To create such UID we use a DB2 Sequence. Right now I already understand that this approach is flawed, since using the database is costly, but it makes sense to do so because this value will also be used to log information on the database. My team has just found out an increase of almost 1000% in elapsed time for each transaction, which we are assuming happened because of the sequence. Now I wonder, using sequences will serialize access to my application? Since they have to guarantee that increments works the way they should, they have to, right? So, are there better strategies when using sequences? Please assume that I have no other way of obtaining a unique id other than relying on the database.

    Read the article

  • Linux: How to find all serial devices (ttyS, ttyUSB and others)?

    - by Thomas Tempelmann
    What is the proper way to get a list of all available serial ports/devices on a Linux system? In other words, when I iterate over all devices in /dev/, how do I tell which ones are serial ports in the classic way, i.e. those usually supporting baud rates and RTS/CTS flow control? The solution would be coded in C. I ask because I am using a 3rd party library that does this clearly wrong: It appears to only iterate over /dev/ttyS*. The problem is that there are, for instance, serial ports over USB (provided by USB-RS232 adapters), and those are listed under /dev/ttyUSB*. And reading the Serial-HOWTO at Linux.org, I get the idea that there'll be other name spaces as well, as time comes. So I need to find the official way to detect serial devices. Problem is that there appears none documented, or I can't find it. I imagine one way would be to open all files from /dev/tty* and call a specific ioctl() on them that is only available on serial devices. Would that be a good solution, though?

    Read the article

  • Nginx not responding to remote IP

    - by bucabay
    I just installed Nginx listening on 8083 I can get a HTTP response when sending a HTTP request from the local machine. eg: curl -i localhost:8083 However, when I do the same from a remote machine, it just hangs until the ssh times out, or when the browser times out if accessed from the browser. I pretty much have the default config: user apache apache; worker_processes 1; error_log logs/error.log; #error_log logs/error.log notice; #error_log logs/error.log info; pid logs/nginx.pid; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log logs/access.log main; sendfile on; tcp_nopush on; #keepalive_timeout 0; keepalive_timeout 65; #gzip on; server { listen 8083; server_name _; charset utf-8; #access_log logs/host.access.log main; location / { root html; index index.html index.php; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root html; } location ~ /\.ht { deny all; } } } any ideas?

    Read the article

  • Reading Serial Data From C (OSX /dev/tty)

    - by Jud Stephenson
    I am trying to read data from a bluetooth barcode scanner (KDC300) using C. Here is the code I have so far, and the program successfully establishes a bluetooth connection to the scanner, but when a barcode is scanned, no input is displayed on the screen (Eventually more will be done with the data, but we have to get it working first, right). Here is the program: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <termios.h> #include <sys/ioctl.h> int main (int argc, const char * argv[]) { // define vars int STOP = 0; //char buf[255]; if(argv[1]) { int fd = open("/dev/tty.KDC1", O_RDONLY); if(fd == -1) { printf("%s", strcat("Unable to open /dev/tty.", argv[1])); } int res; while(STOP == 0) { while((res = read(fd,buf,255)) == 0); { if(res > 0) { buf[res]=0; printf("%s:%d\n", buf, res); if(buf[sizeof(buf)]=='\n') break; } } } } return 0; } If anyone has any ideas, I am at a loss on this so far. If it is any help, I can run screen /dev/tty.KDC1 and any barcodes scanned on the scanner appear in the terminal, I just can't do anything with the data. Jud

    Read the article

  • Submitting R jobs using PBS

    - by Tony
    I am submitting a job using qsub that runs parallelized R. My intention is to have R programme running on 4 different cores rather than 8 cores. Here are some of my settings in PBS file: #PBS -l nodes=1:ppn=4 .... time R --no-save < program1.R > program1.log I am issuing the command "ta job_id" and I'm seeing that 4 cores are listed. However, the job occupies a large amount of memory(31944900k used vs 32949628k total). If I were to use 8 cores, the jobs got hang due to memory limitation. top - 21:03:53 up 77 days, 11:54, 0 users, load average: 3.99, 3.75, 3.37 Tasks: 207 total, 5 running, 202 sleeping, 0 stopped, 0 zombie Cpu(s): 30.4%us, 1.6%sy, 0.0%ni, 66.8%id, 0.0%wa, 0.0%hi, 1.2%si, 0.0%st Mem: 32949628k total, 31944900k used, 1004728k free, 269812k buffers Swap: 2097136k total, 8360k used, 2088776k free, 6030856k cached Here is a snapshot when issuing command ta job_id PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1794 x 25 0 6247m 6.0g 1780 R 99.2 19.1 8:14.37 R 1795 x 25 0 6332m 6.1g 1780 R 99.2 19.4 8:14.37 R 1796 x 25 0 6242m 6.0g 1784 R 99.2 19.1 8:14.37 R 1797 x 25 0 6322m 6.1g 1780 R 99.2 19.4 8:14.33 R 1714 x 18 0 65932 1504 1248 S 0.0 0.0 0:00.00 bash 1761 x 18 0 63840 1244 1052 S 0.0 0.0 0:00.00 20016.hpc 1783 x 18 0 133m 7096 1128 S 0.0 0.0 0:00.00 python 1786 x 18 0 137m 46m 2688 S 0.0 0.1 0:02.06 R How can I prevent other users to use the other 4 cores? I like to mask somehow that my job is using 8 cores with 4 cores idling. Could anyone kindly help me out on this? Can this be solved using pbs? Many Thanks

    Read the article

  • MPIexec.exe Access denide

    - by shake
    I have installed microsoft compute cluster and MPI.net, now i have trouble to run program using mpiexec.exe on cluster. When i try to run it on console i get message: "Access Denied", and pop up: "mpiexec.exe is not valid win32 application". I tried google it, but found nothing. Pls help. :)

    Read the article

  • Linux: How to find all serial devices (ttyS, ttyUSB, ..) without opening them?

    - by Thomas Tempelmann
    What is the proper way to get a list of all available serial ports/devices on a Linux system? In other words, when I iterate over all devices in /dev/, how do I tell which ones are serial ports in the classic way, i.e. those usually supporting baud rates and RTS/CTS flow control? The solution would be coded in C. I ask because I am using a 3rd party library that does this clearly wrong: It appears to only iterate over /dev/ttyS*. The problem is that there are, for instance, serial ports over USB (provided by USB-RS232 adapters), and those are listed under /dev/ttyUSB*. And reading the Serial-HOWTO at Linux.org, I get the idea that there'll be other name spaces as well, as time comes. So I need to find the official way to detect serial devices. Problem is that there appears none documented, or I can't find it. I imagine one way would be to open all files from /dev/tty* and call a specific ioctl() on them that is only available on serial devices. Would that be a good solution, though? Update hrickards suggested to look at the source for "setserial". Its code does exactly what I had in mind: First, it opens a device with: fd = open (path, O_RDWR | O_NONBLOCK) Then it invokes: ioctl (fd, TIOCGSERIAL, &serinfo) If that call returns no error, then it's a serial dev, apparently. I found similar code here, which suggested to also add the O_NOCTTY option. There is one problem with this approach, though: When I tested this code on BSD Unix (i.e. OSX), it worked as well, however serial devices that are provided thru Bluetooth cause the system (driver) to try to connect to the bluetooth device, which takes a while before it'll return with a timeout error. This is caused by just opening the device. And I can imagine that similar things can happen on Linux as well - ideally, I should not need to open the device to figure out its type. I wonder if there's also a way to invoke ioctl functions without an open, or open a device in a way that it does not cause connections to be made? Any ideas?

    Read the article

  • Which comm ports exist? Win32

    - by myforwik
    On win32, using winapi, is there anyway to know which comports (from com0 upwards) actually exist as devices? At the moment I am just attemping to open them all (0 to 9), but I can't figure out the difference of failure between one not existing, and one not simply being available for use because someone else is using it. Both situations seem to return the same last error, so I was wondering if I could list all the comports available on the system.

    Read the article

  • I don't understand how work call_once

    - by SABROG
    Please help me understand how work call_once Here is thread-safe code. I don't understand why this need Thread Local Storage and global_epoch variables. Variable _fast_pthread_once_per_thread_epoch can be changed to constant/enum like {FAST_PTHREAD_ONCE_INIT, BEING_INITIALIZED, FINISH_INITIALIZED}. Why needed count calls in global_epoch? I think this code can be rewriting with logc: if flag FINISH_INITIALIZED do nothing, else go to block with mutexes and this all. #ifndef FAST_PTHREAD_ONCE_H #define FAST_PTHREAD_ONCE_H #include #include typedef sig_atomic_t fast_pthread_once_t; #define FAST_PTHREAD_ONCE_INIT SIG_ATOMIC_MAX extern __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; #ifdef __cplusplus extern "C" { #endif extern void fast_pthread_once( pthread_once_t *once, void (*func)(void) ); inline static void fast_pthread_once_inline( fast_pthread_once_t *once, void (*func)(void) ) { fast_pthread_once_t x = *once; /* unprotected access */ if ( x _fast_pthread_once_per_thread_epoch ) { fast_pthread_once( once, func ); } } #ifdef __cplusplus } #endif #endif FAST_PTHREAD_ONCE_H Source fast_pthread_once.c The source is written in C. The lines of the primary function are numbered for reference in the subsequent correctness argument. #include "fast_pthread_once.h" #include static pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER; /* protects global_epoch and all fast_pthread_once_t writes */ static pthread_cond_t cv = PTHREAD_COND_INITIALIZER; /* signalled whenever a fast_pthread_once_t is finalized */ #define BEING_INITIALIZED (FAST_PTHREAD_ONCE_INIT - 1) static fast_pthread_once_t global_epoch = 0; /* under mu */ __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; static void check( int x ) { if ( x == 0 ) abort(); } void fast_pthread_once( fast_pthread_once_t *once, void (*func)(void) ) { /*01*/ fast_pthread_once_t x = *once; /* unprotected access */ /*02*/ if ( x _fast_pthread_once_per_thread_epoch ) { /*03*/ check( pthread_mutex_lock(µ) == 0 ); /*04*/ if ( *once == FAST_PTHREAD_ONCE_INIT ) { /*05*/ *once = BEING_INITIALIZED; /*06*/ check( pthread_mutex_unlock(µ) == 0 ); /*07*/ (*func)(); /*08*/ check( pthread_mutex_lock(µ) == 0 ); /*09*/ global_epoch++; /*10*/ *once = global_epoch; /*11*/ check( pthread_cond_broadcast(&cv;) == 0 ); /*12*/ } else { /*13*/ while ( *once == BEING_INITIALIZED ) { /*14*/ check( pthread_cond_wait(&cv;, µ) == 0 ); /*15*/ } /*16*/ } /*17*/ _fast_pthread_once_per_thread_epoch = global_epoch; /*18*/ check (pthread_mutex_unlock(µ) == 0); } } This code from BOOST: #ifndef BOOST_THREAD_PTHREAD_ONCE_HPP #define BOOST_THREAD_PTHREAD_ONCE_HPP // once.hpp // // (C) Copyright 2007-8 Anthony Williams // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #include #include #include #include "pthread_mutex_scoped_lock.hpp" #include #include #include namespace boost { struct once_flag { boost::uintmax_t epoch; }; namespace detail { BOOST_THREAD_DECL boost::uintmax_t& get_once_per_thread_epoch(); BOOST_THREAD_DECL extern boost::uintmax_t once_global_epoch; BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex; BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv; } #define BOOST_ONCE_INITIAL_FLAG_VALUE 0 #define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE} // Based on Mike Burrows fast_pthread_once algorithm as described in // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2444.html template void call_once(once_flag& flag,Function f) { static boost::uintmax_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE; static boost::uintmax_t const being_initialized=uninitialized_flag+1; boost::uintmax_t const epoch=flag.epoch; boost::uintmax_t& this_thread_epoch=detail::get_once_per_thread_epoch(); if(epoch #endif I right understand, boost don't use atomic operation, so code from boost not thread-safe?

    Read the article

  • Bitbanging a PIO on Coldfire/ucLinux

    - by G Forty
    Here's the problem: I need to program some hardware via 2 pins of the PIO (1 clock, 1 data). Timing constraints are tight - 10ms clock cycle time. All this, of course, whilst I maintain very high level services (CAN bus, TCP/IP). The downstream unit also ACKS by asserting a PIO pin, configured as an input, high. So this loop has to both read and write. I need to send 16 bits in the serial stream. Is there an established way to do this sort of thing or should I simply get the hardware guys to add a PIC or somesuch. I'd much prefer to avoid exotics like RTAI extensions at this stage. I did once see a reference to user-mode IO which implied a possible interrupt driven driver but lost track of it. Any pointers welcomed.

    Read the article

  • CPU Affinity Masks (Putting Threads on different CPUs)

    - by hahuang65
    I have 4 threads, and I am trying to set thread 1 to run on CPU 1, thread 2 on CPU 2, etc. However, when I run my code below, the affinity masks are returning the correct values, but when I do a sched_getcpu() on the threads, they all return that they are running on CPU 4. Anybody know what my problem here is? Thanks in advance! #define _GNU_SOURCE #include <stdio.h> #include <pthread.h> #include <stdlib.h> #include <sched.h> #include <errno.h> void *pthread_Message(char *message) { printf("%s is running on CPU %d\n", message, sched_getcpu()); } int main() { pthread_t thread1, thread2, thread3, thread4; pthread_t threadArray[4]; cpu_set_t cpu1, cpu2, cpu3, cpu4; char *thread1Msg = "Thread 1"; char *thread2Msg = "Thread 2"; char *thread3Msg = "Thread 3"; char *thread4Msg = "Thread 4"; int thread1Create, thread2Create, thread3Create, thread4Create, i, temp; CPU_ZERO(&cpu1); CPU_SET(1, &cpu1); temp = pthread_setaffinity_np(thread1, sizeof(cpu_set_t), &cpu1); printf("Set returned by pthread_getaffinity_np() contained:\n"); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu1)) printf("CPU1: CPU %d\n", i); CPU_ZERO(&cpu2); CPU_SET(2, &cpu2); temp = pthread_setaffinity_np(thread2, sizeof(cpu_set_t), &cpu2); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu2)) printf("CPU2: CPU %d\n", i); CPU_ZERO(&cpu3); CPU_SET(3, &cpu3); temp = pthread_setaffinity_np(thread3, sizeof(cpu_set_t), &cpu3); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu3)) printf("CPU3: CPU %d\n", i); CPU_ZERO(&cpu4); CPU_SET(4, &cpu4); temp = pthread_setaffinity_np(thread4, sizeof(cpu_set_t), &cpu4); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu4)) printf("CPU4: CPU %d\n", i); thread1Create = pthread_create(&thread1, NULL, (void *)pthread_Message, thread1Msg); thread2Create = pthread_create(&thread2, NULL, (void *)pthread_Message, thread2Msg); thread3Create = pthread_create(&thread3, NULL, (void *)pthread_Message, thread3Msg); thread4Create = pthread_create(&thread4, NULL, (void *)pthread_Message, thread4Msg); pthread_join(thread1, NULL); pthread_join(thread2, NULL); pthread_join(thread3, NULL); pthread_join(thread4, NULL); return 0; }

    Read the article

  • .net 4.0 concurrent queue dictionary

    - by freddy smith
    I would like to use the new concurrent collections in .NET 4.0 to solve the following problem. The basic data structure I want to have is a producer consumer queue, there will be a single consumer and multiple producers. There are items of type A,B,C,D,E that will be added to this queue. Items of type A,B,C are added to the queue in the normal manner and processed in order. However items of type D or E can only exist in the queue zero or once. If one of these is to be added and there already exists another of the same type that has not yet been processed then this should update that other one in-place in the queue. The queue position would not change (i.e. would not go to the back of the queue) after the update. Which .NET 4.0 classes would be best for this?

    Read the article

  • How does Batcher Merge work at a high level?

    - by Mike
    I'm trying to grasp the concept of a Batcher Sort. However, most resources I've found online focus on proof entirely or on low-level pseudocode. Before I look at proofs, I'd like to understand how Batcher Sort works. Can someone give a high level overview of how Batcher Sort works(particularly the merge) without overly verbose pseudocode(I want to get the idea behind the Batcher Sort, not implement it)? Thanks!

    Read the article

  • Parallelism in Python

    - by fmark
    What are the options for achieving parallelism in Python? I want to perform a bunch of CPU bound calculations over some very large rasters, and would like to parallelise them. Coming from a C background, I am familiar with three approaches to parallelism: Message passing processes, possibly distributed across a cluster, e.g. MPI. Explicit shared memory parallelism, either using pthreads or fork(), pipe(), et. al Implicit shared memory parallelism, using OpenMP. Deciding on an approach to use is an exercise in trade-offs. In Python, what approaches are available and what are their characteristics? Is there a clusterable MPI clone? What are the preferred ways of achieving shared memory parallelism? I have heard reference to problems with the GIL, as well as references to tasklets. In short, what do I need to know about the different parallelization strategies in Python before choosing between them?

    Read the article

  • Porting SHA512 Javascript implemention to Actionscript

    - by AAA
    Hello Everyone, I am wondering if anyone can help me in porting a SHA-512 implemention in Javascript to Actionscript. Since both Javascript and Actionscript share the same origin, I think porting it will be easy for people who are used to Actionscript. The code for sha512 in javascript can be found here: http://pajhome.org.uk/crypt/md5/sha512.html Thank you.

    Read the article

  • Python: Plot some data (matplotlib) without GIL

    - by BandGap
    Hello all, my problem is the GIL of course. While I'm analysing data it would be nice to present some plots in between (so it's not too boring waiting for results) But the GIL prevents this (and this is bringing me to the point of asking myself if Python was such a good idea in the first place). I can only display the plot, wait till the user closes it and commence calculations after that. A waste of time obviously. I already tried the subprocess and multiprocessing modules but can't seem to get them to work. Any thoughts on this one? Thanks

    Read the article

  • How to Profile R Code that Includes SNOW Cluster

    - by James
    Hi, I have a nested loop that I'm using foreach, DoSNOW, and a SNOW socket cluster to solve for. How should I go about profiling the code to make sure I'm not doing something grossly inefficient. Also is there anyway to measure the data flows going between the master and nodes in a Snow cluster? Thanks, James

    Read the article

  • Is there an existing solution to the multithreaded data structure problem?

    - by thr
    I've had the need for a multi-threaded data structure that supports these claims: Allows multiple concurrent readers and writers Is sorted Is easy to reason about Fulfilling multiple readers and one writer is a lot easier, but I really would wan't to allow multiple writers. I've been doing research into this area, and I'm aware of ConcurrentSkipList (by Lea based on work by Fraser and Harris) as it's implemented in Java SE 6. I've also implemented my own version of a concurrent Skip List based on A Provably Correct Scalable Concurrent Skip List by Herlihy, Lev, Luchangco and Shavit. These two implementations are developed by people that are light years smarter then me, but I still (somewhat ashamed, because it is amazing work) have to ask the question if these are the two only viable implementations of a concurrent multi reader/writer data structures available today?

    Read the article

  • parallelizing code using openmp

    - by anubhav
    Hi, The function below contains nested for loops. There are 3 of them. I have given the whole function below for easy understanding. I want to parallelize the code in the innermost for loop as it takes maximum CPU time. Then i can think about outer 2 for loops. I can see dependencies and internal inline functions in the innermost for loop . Can the innermost for loop be rewritten to enable parallelization using openmp pragmas. Please tell how. I am writing just the loop which i am interested in first and then the full function where this loop exists for referance. Interested in parallelizing the loop mentioned below. //* LOOP WHICH I WANT TO PARALLELIZE *// for (y = 0; y < 4; y++) { refptr = PelYline_11 (ref_pic, abs_y++, abs_x, img_height, img_width); LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; } The full function where this loop exists is below for referance. /*! *********************************************************************** * \brief * Setup the fast search for an macroblock *********************************************************************** */ void SetupFastFullPelSearch (short ref, int list) // <-- reference frame parameter, list0 or 1 { short pmv[2]; pel_t orig_blocks[256], *orgptr=orig_blocks, *refptr, *tem; // created pointer tem int offset_x, offset_y, x, y, range_partly_outside, ref_x, ref_y, pos, abs_x, abs_y, bindex, blky; int LineSadBlk0, LineSadBlk1, LineSadBlk2, LineSadBlk3; int max_width, max_height; int img_width, img_height; StorablePicture *ref_picture; pel_t *ref_pic; int** block_sad = BlockSAD[list][ref][7]; int search_range = max_search_range[list][ref]; int max_pos = (2*search_range+1) * (2*search_range+1); int list_offset = ((img->MbaffFrameFlag)&&(img->mb_data[img->current_mb_nr].mb_field))? img->current_mb_nr%2 ? 4 : 2 : 0; int apply_weights = ( (active_pps->weighted_pred_flag && (img->type == P_SLICE || img->type == SP_SLICE)) || (active_pps->weighted_bipred_idc && (img->type == B_SLICE))); ref_picture = listX[list+list_offset][ref]; //===== Use weighted Reference for ME ==== if (apply_weights && input->UseWeightedReferenceME) ref_pic = ref_picture->imgY_11_w; else ref_pic = ref_picture->imgY_11; max_width = ref_picture->size_x - 17; max_height = ref_picture->size_y - 17; img_width = ref_picture->size_x; img_height = ref_picture->size_y; //===== get search center: predictor of 16x16 block ===== SetMotionVectorPredictor (pmv, enc_picture->ref_idx, enc_picture->mv, ref, list, 0, 0, 16, 16); search_center_x[list][ref] = pmv[0] / 4; search_center_y[list][ref] = pmv[1] / 4; if (!input->rdopt) { //--- correct center so that (0,0) vector is inside --- search_center_x[list][ref] = max(-search_range, min(search_range, search_center_x[list][ref])); search_center_y[list][ref] = max(-search_range, min(search_range, search_center_y[list][ref])); } search_center_x[list][ref] += img->opix_x; search_center_y[list][ref] += img->opix_y; offset_x = search_center_x[list][ref]; offset_y = search_center_y[list][ref]; //===== copy original block for fast access ===== for (y = img->opix_y; y < img->opix_y+16; y++) for (x = img->opix_x; x < img->opix_x+16; x++) *orgptr++ = imgY_org [y][x]; //===== check if whole search range is inside image ===== if (offset_x >= search_range && offset_x <= max_width - search_range && offset_y >= search_range && offset_y <= max_height - search_range ) { range_partly_outside = 0; PelYline_11 = FastLine16Y_11; } else { range_partly_outside = 1; } //===== determine position of (0,0)-vector ===== if (!input->rdopt) { ref_x = img->opix_x - offset_x; ref_y = img->opix_y - offset_y; for (pos = 0; pos < max_pos; pos++) { if (ref_x == spiral_search_x[pos] && ref_y == spiral_search_y[pos]) { pos_00[list][ref] = pos; break; } } } //===== loop over search range (spiral search): get blockwise SAD ===== **// =====THIS IS THE PART WHERE NESTED FOR STARTS=====** for (pos = 0; pos < max_pos; pos++) // OUTERMOST FOR LOOP { abs_y = offset_y + spiral_search_y[pos]; abs_x = offset_x + spiral_search_x[pos]; if (range_partly_outside) { if (abs_y >= 0 && abs_y <= max_height && abs_x >= 0 && abs_x <= max_width ) { PelYline_11 = FastLine16Y_11; } else { PelYline_11 = UMVLine16Y_11; } } orgptr = orig_blocks; bindex = 0; for (blky = 0; blky < 4; blky++) // SECOND FOR LOOP { LineSadBlk0 = LineSadBlk1 = LineSadBlk2 = LineSadBlk3 = 0; for (y = 0; y < 4; y++) //INNERMOST FOR LOOP WHICH I WANT TO PARALLELIZE { refptr = PelYline_11 (ref_pic, abs_y++, abs_x, img_height, img_width); LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk0 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk1 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk2 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; LineSadBlk3 += byte_abs [*refptr++ - *orgptr++]; } block_sad[bindex++][pos] = LineSadBlk0; block_sad[bindex++][pos] = LineSadBlk1; block_sad[bindex++][pos] = LineSadBlk2; block_sad[bindex++][pos] = LineSadBlk3; } } //===== combine SAD's for larger block types ===== SetupLargerBlocks (list, ref, max_pos); //===== set flag marking that search setup have been done ===== search_setup_done[list][ref] = 1; } #endif // _FAST_FULL_ME_

    Read the article

< Previous Page | 75 76 77 78 79 80 81 82 83 84 85 86  | Next Page >