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  • Faster way to convert from 24 bit wav pcm format to float?

    - by LMO
    I need to read data in from a wav file in 24 bit pcm format, and convert to float. I'm using Python 2.7.2. The wave package reads the data in as a string, so what I've tried is: # read in entire wav file wdata = f.readframes(nFrames) # unpack into signed integers and convert to float data = array.array('f') for i in range(0,nFrames*3,3): data.append(float(struct.unpack('<i', '\x00'+ wdata[i:i+3])[0])) # normalize sample values data = data / 0x800000 This is quite a bit faster than my earlier approaches, but still quite slow. Can anyone suggest a more efficient method?

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  • NASM: Count how many bits in a 32 Bit number are set to 1.

    - by citronas
    I have a 32 Bit number and want to count know how many bits are 1. I'm thinking of this pseudocode: mov eax, [number] while(eax != 0) { div eax, 2 if(edx == 1) { ecx++; } shr eax, 1 } Is there a more efficient way? I'm using NASM on a x86 processor. (I'm just beginning with assembler, so please do not tell me to use code from extern libraries, because I do not even know how to include them ;) ) (I just found http://stackoverflow.com/questions/109023/best-algorithm-to-count-the-number-of-set-bits-in-a-32-bit-integer which also contains my solution. There are other solutions posted, but unfortunatly I can't seem to figure out, how I would write them in assembler)

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  • How can I access the sign bit of a number in C++?

    - by Keand64
    I want to be able to access the sign bit of a number in C++. My current code looks something like this: int sign bit = number >> 31; That appears to work, giving me 0 for positive numbers and -1 for negative numbers. However, I don't see how I get -1 for negative numbers: if 12 is 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 1100 then -12 is 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 0011 and shifting it 31 bits would make 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0001 which is 1, not -1, so why do I get -1 when I shift it?

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  • How to reliably specialize template with intptr_t in 32 and 64 bit environments?

    - by vava
    I have a template I want to specialize with two int types, one of them plain old int and another one is intptr_t. On 64 bit platform they have different sizes and I can do that with ease but on 32 bit both types are the same and compiler throws an error about redefinition. What can I do to fix it except for disabling one of definitions off with preprocessor? Some code as an example: template<typename T> type * convert(); template<> type * convert<int>() { return getProperIntType(sizeof(int)); } template<> type * convert<intptr_t>() { return getProperIntType(sizeof(intptr_t)); } //this template can be specialized with non-integral types as well, // so I can't just use sizeof() as template parameter. template<> type * convert<void>() { return getProperVoidType(); }

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  • How do you specify a 64 bit unsigned int const 0x8000000000000000 in VS2008?

    - by Mark Franjione
    I read about the Microsoft specific suffix "i64" for integer constants. I want to do an UNsigned shift to a ULONGLONG. ULONGLONG bigNum64 = 0x800000000000000i64 >> myval; In normal C, I would use the suffix "U", e.g. the similar 32 bit operation would be ULONG bigNum32 = 0x80000000U >> myval; I do NOT want the 2's complement sign extension to propogate through the high bits. I want an UNSIGNED shift on a 64 bit const number. I think my first statement is going to do a SIGNED shift right. I tried 0x800000000000000i64U and 0x800000000000000u64 but got compiler errors.

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  • Is there a way to have a bit bucket pointer? (C/C++)

    - by Crazy Chenz
    Is there a way to have a bit bucket pointer? A lot of IO (specifically input related) system calls return data to a buffer of a specific size. Is there a trick or way to make a sorta bit bucket pointer, so I can accept any amount of data that will be thrown away. Doing something like "char tmp[INT_MAX]" is crazy. The behavior I am looking for is something like /dev/null, only in a pointer world. Not to hopeful on this.... just curious. Thanks, Chenz UPDATE: Perhaps mmap-ing /dev/null. Forgot about that when I asked the question.

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  • For LinqToSQL is 0 true or is 1 (for type Bit)?

    - by Vaccano
    I have a column of type Bit (called BBoolVal in this example). I have a LinqToSQL Statement Like this: var query = List<MyClass> myList = _ctx.DBList .Where(x => x.AGuidID == paramID) .Where(x => x.BBoolVal == false); When I look at the sql it ends up like this (I added the spacing and changed the names): SELECT [t0].[Id], [t0].[AGuidID], [t0].[OtherIDID], [t0].[TimeColumn], [t0].[BBoolVal], [t0].[MoreID] FROM [dbo].[MyTable] AS [t0] WHERE (NOT ([t0].[BBoolVal] = 1)) AND ([t0].[AGuidID] = @p0) Because my x.BBoolVal == false translates to [BBoolVal] == 1 I gather that false = 1 (and thus true = 0). I am asking because this seems a bit backwards to me. I am fine to accept it, I just want to be sure.

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  • What does "single-bit ECC errors were detected on the RAID controller" mean?

    - by jsp
    I have a Dell T7600 with a Perc H710P RAID controller and 4 attached 3TB drives. Over the past few months the RAID controller has been intermittently reporting errors on boot: "no boot device found", "adapter at baseport is not responding", disks frequently reported as missing or failed. I have since replaced the RAID controller, the 4 hard drives, and finally the system's motherboard. After replacing the motherboard and rebooting a few times, I got the error Single bit ECC errors were detected on the RAID controller. Please contact technical support to resolve this issue. After rebooting about 20 more times, I haven't seen the ECC error. The system seems otherwise OK, except for the fact that the disk fans will sometimes start blowing at full blast when the the system is sitting completely idle and not stop until I reboot. Are the ECC errors in memory on the RAID controller? Or, does the RAID controller map in system memory, and the ECC errors are really in system memory? Or, are the ECC errors in the 1GB cache that resides in the RAID controller?

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  • Can I install two Ubuntu versions on the same machine

    - by abh
    Hello, I have Ubuntu 10.10 32 bit already installed on my machine. I am using MongoDB and it does not work properly with 32 bit machine. So I want to install 64 bit Ubuntu 10.10 on my system on another partition(So that I can have both 32 bit and 64 bit versions). Is it okay to install both 32 bit and 64 bit. I mean will it give any problem? and on which partition I should install 64 bit version ..my partitions are as follows Filesystem Size Used Avail Use% Mounted on /dev/sda1 37G 11G 25G 30% / none 1.4G 260K 1.4G 1% /dev none 1.4G 776K 1.4G 1% /dev/shm none 1.4G 244K 1.4G 1% /var/run none 1.4G 0 1.4G 0% /var/lock /dev/sda6 129G 73G 50G 60% /home /dev/sda7 127G 76G 45G 64% /vol Waiting for your replies.

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  • Thread placement policies on NUMA systems - update

    - by Dave
    In a prior blog entry I noted that Solaris used a "maximum dispersal" placement policy to assign nascent threads to their initial processors. The general idea is that threads should be placed as far away from each other as possible in the resource topology in order to reduce resource contention between concurrently running threads. This policy assumes that resource contention -- pipelines, memory channel contention, destructive interference in the shared caches, etc -- will likely outweigh (a) any potential communication benefits we might achieve by packing our threads more densely onto a subset of the NUMA nodes, and (b) benefits of NUMA affinity between memory allocated by one thread and accessed by other threads. We want our threads spread widely over the system and not packed together. Conceptually, when placing a new thread, the kernel picks the least loaded node NUMA node (the node with lowest aggregate load average), and then the least loaded core on that node, etc. Furthermore, the kernel places threads onto resources -- sockets, cores, pipelines, etc -- without regard to the thread's process membership. That is, initial placement is process-agnostic. Keep reading, though. This description is incorrect. On Solaris 10 on a SPARC T5440 with 4 x T2+ NUMA nodes, if the system is otherwise unloaded and we launch a process that creates 20 compute-bound concurrent threads, then typically we'll see a perfect balance with 5 threads on each node. We see similar behavior on an 8-node x86 x4800 system, where each node has 8 cores and each core is 2-way hyperthreaded. So far so good; this behavior seems in agreement with the policy I described in the 1st paragraph. I recently tried the same experiment on a 4-node T4-4 running Solaris 11. Both the T5440 and T4-4 are 4-node systems that expose 256 logical thread contexts. To my surprise, all 20 threads were placed onto just one NUMA node while the other 3 nodes remained completely idle. I checked the usual suspects such as processor sets inadvertently left around by colleagues, processors left offline, and power management policies, but the system was configured normally. I then launched multiple concurrent instances of the process, and, interestingly, all the threads from the 1st process landed on one node, all the threads from the 2nd process landed on another node, and so on. This happened even if I interleaved thread creating between the processes, so I was relatively sure the effect didn't related to thread creation time, but rather that placement was a function of process membership. I this point I consulted the Solaris sources and talked with folks in the Solaris group. The new Solaris 11 behavior is intentional. The kernel is no longer using a simple maximum dispersal policy, and thread placement is process membership-aware. Now, even if other nodes are completely unloaded, the kernel will still try to pack new threads onto the home lgroup (socket) of the primordial thread until the load average of that node reaches 50%, after which it will pick the next least loaded node as the process's new favorite node for placement. On the T4-4 we have 64 logical thread contexts (strands) per socket (lgroup), so if we launch 48 concurrent threads we will find 32 placed on one node and 16 on some other node. If we launch 64 threads we'll find 32 and 32. That means we can end up with our threads clustered on a small subset of the nodes in a way that's quite different that what we've seen on Solaris 10. So we have a policy that allows process-aware packing but reverts to spreading threads onto other nodes if a node becomes too saturated. It turns out this policy was enabled in Solaris 10, but certain bugs suppressed the mixed packing/spreading behavior. There are configuration variables in /etc/system that allow us to dial the affinity between nascent threads and their primordial thread up and down: see lgrp_expand_proc_thresh, specifically. In the OpenSolaris source code the key routine is mpo_update_tunables(). This method reads the /etc/system variables and sets up some global variables that will subsequently be used by the dispatcher, which calls lgrp_choose() in lgrp.c to place nascent threads. Lgrp_expand_proc_thresh controls how loaded an lgroup must be before we'll consider homing a process's threads to another lgroup. Tune this value lower to have it spread your process's threads out more. To recap, the 'new' policy is as follows. Threads from the same process are packed onto a subset of the strands of a socket (50% for T-series). Once that socket reaches the 50% threshold the kernel then picks another preferred socket for that process. Threads from unrelated processes are spread across sockets. More precisely, different processes may have different preferred sockets (lgroups). Beware that I've simplified and elided details for the purposes of explication. The truth is in the code. Remarks: It's worth noting that initial thread placement is just that. If there's a gross imbalance between the load on different nodes then the kernel will migrate threads to achieve a better and more even distribution over the set of available nodes. Once a thread runs and gains some affinity for a node, however, it becomes "stickier" under the assumption that the thread has residual cache residency on that node, and that memory allocated by that thread resides on that node given the default "first-touch" page-level NUMA allocation policy. Exactly how the various policies interact and which have precedence under what circumstances could the topic of a future blog entry. The scheduler is work-conserving. The x4800 mentioned above is an interesting system. Each of the 8 sockets houses an Intel 7500-series processor. Each processor has 3 coherent QPI links and the system is arranged as a glueless 8-socket twisted ladder "mobius" topology. Nodes are either 1 or 2 hops distant over the QPI links. As an aside the mapping of logical CPUIDs to physical resources is rather interesting on Solaris/x4800. On SPARC/Solaris the CPUID layout is strictly geographic, with the highest order bits identifying the socket, the next lower bits identifying the core within that socket, following by the pipeline (if present) and finally the logical thread context ("strand") on the core. But on Solaris on the x4800 the CPUID layout is as follows. [6:6] identifies the hyperthread on a core; bits [5:3] identify the socket, or package in Intel terminology; bits [2:0] identify the core within a socket. Such low-level details should be of interest only if you're binding threads -- a bad idea, the kernel typically handles placement best -- or if you're writing NUMA-aware code that's aware of the ambient placement and makes decisions accordingly. Solaris introduced the so-called critical-threads mechanism, which is expressed by putting a thread into the FX scheduling class at priority 60. The critical-threads mechanism applies to placement on cores, not on sockets, however. That is, it's an intra-socket policy, not an inter-socket policy. Solaris 11 introduces the Power Aware Dispatcher (PAD) which packs threads instead of spreading them out in an attempt to be able to keep sockets or cores at lower power levels. Maximum dispersal may be good for performance but is anathema to power management. PAD is off by default, but power management polices constitute yet another confounding factor with respect to scheduling and dispatching. If your threads communicate heavily -- one thread reads cache lines last written by some other thread -- then the new dense packing policy may improve performance by reducing traffic on the coherent interconnect. On the other hand if your threads in your process communicate rarely, then it's possible the new packing policy might result on contention on shared computing resources. Unfortunately there's no simple litmus test that says whether packing or spreading is optimal in a given situation. The answer varies by system load, application, number of threads, and platform hardware characteristics. Currently we don't have the necessary tools and sensoria to decide at runtime, so we're reduced to an empirical approach where we run trials and try to decide on a placement policy. The situation is quite frustrating. Relatedly, it's often hard to determine just the right level of concurrency to optimize throughput. (Understanding constructive vs destructive interference in the shared caches would be a good start. We could augment the lines with a small tag field indicating which strand last installed or accessed a line. Given that, we could augment the CPU with performance counters for misses where a thread evicts a line it installed vs misses where a thread displaces a line installed by some other thread.)

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  • Looking for best practice for version numbering of dependent software components

    - by bit-pirate
    We are trying to decide on a good way to do version numbering for software components, which are depending on each other. Let's be more specific: Software component A is a firmware running on an embedded device and component B is its respective driver for a normal PC (Linux/Windows machine). They are communicating with each other using a custom protocol. Since, our product is also targeted at developers, we will offer stable and unstable (experimental) versions of both components (the firmware is closed-source, while the driver is open-source). Our biggest difficulty is how to handle API changes in the communication protocol. While we were implementing a compatibility check in the driver - it checks if the firmware version is compatible to the driver's version - we started to discuss multiple ways of version numbering. We came up with one solution, but we also felt like reinventing the wheel. That is why I'd like to get some feedback from the programmer/software developer community, since we think this is a common problem. So here is our solution: We plan to follow the widely used major.minor.patch version numbering and to use even/odd minor numbers for the stable/unstable versions. If we introduce changes in the API, we will increase the minor number. This convention will lead to the following example situation: Current stable branch is 1.2.1 and unstable is 1.3.7. Now, a new patch for unstable changes the API, what will cause the new unstable version number to become 1.5.0. Once, the unstable branch is considered stable, let's say in 1.5.3, we will release it as 1.4.0. I would be happy about an answer to any of the related questions below: Can you suggest a best practice for handling the issues described above? Do you think our "custom" convention is good? What changes would you apply to the described convention? Thanks a lot for your feedback! PS: Since I'm new here, I can't create new tags (e.g. best-practice). So, I'm wondering if best-pactice is just misspelled or I don't get its meaning.

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  • Should I be paid for time spent learning a framework?

    - by nate-bit
    To give light to the situation: I am currently one of two programmers working in a small startup software company. Part of my job requires me to learn a Web development framework that I am not currently familiar with. I get paid by the hour. So the question is: Is it wholly ethical to spend multiple hours of the day reading through documentation and tutorials and be paid for this time where I am not actively developing for our product? Or should the bulk of this learning be done at home, or otherwise off hours, to allow for more full-on development of our application during the work day?

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  • Will Windows 7 work at all on my old toshiba [closed]

    - by andrew
    Windows 7 requires the following specifications: 1 gigahertz (GHz) or faster 32-bit (x86) or 64-bit (x64) processor 1 gigabyte (GB) RAM (32-bit) or 2 GB RAM (64-bit) 16 GB available hard disk space (32-bit) or 20 GB (64-bit) DirectX 9 graphics device with WDDM 1.0 or higher driver Will it work at all on my old toshiba Satellite A100 PSAA8C-SK400E Intel® Core™ Solo processor T1350 (1.86GHz, 533MHz FSB, L1 Cache 32KB/32KB, L2 Cache 2MB) Standard Memory: 2x512 MB DDR2 Intel® Graphics Media Accelerator 950 with 8MB-128MB. The main problem I can see is that the graphics is not up to it.

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  • Should I be paid for time spent learning a framework?

    - by nate-bit
    To give light to the situation: I am currently one of two programmers working in a small startup software company. Part of my job requires me to learn a Web development framework that I am not currently familiar with. I get paid by the hour. So the question is: Is it wholly ethical to spend multiple hours of the day reading through documentation and tutorials and be paid for this time where I am not actively developing for our product? Or should the bulk of this learning be done at home, or otherwise off hours, to allow for more full-on development of our application during the work day?

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  • Who spotted the omission?

    - by olaf.heimburger
    In my entry OFM 11g: Install OAM 10.1.4.3 (32-bit) on 64-bit RedHat AS 5 I explained how to install OAM 10.1.4.3 (32-bit) on 64-bit RedHat. This is great and works. If you seriously want to use OAM 10.1.4.3 you should consider OHS 11g 32-bit. But this installation is a bit tricky. Nearly all tricks to get this done are described in the above mentioned entry. Today I realized that I missed a small bit to get the installation successfully done.The missing part is within the script to create a vital piece of the OHS 11g package. This part is called genclientsh and resides in $OHS_HOME/bin. This script uses gcc to link binaries. By default this script works great, but on a 64-bit Linux it fails. To get around this, find the variable LD and change the value of gcc to gcc -m32.Done. Caveat On support.oracle.com you will find a Note that suggests to build a small shell script named gcc and includes the -m32 switch. Actually, I consider this as dangerous, because we are humans and tend to forget things quickly. Building a globally available script that changes things for a single setup has side effects that will result in unpredictable results.

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  • Why does Outlook 2007 lose connection to Exchange when Windows 7 64-bit turns off display?

    - by Greg R.
    The problem: When Windows 7 puts the display to sleep, Outlook 2007 and also Microsoft Office Communicator 2005 lose the connection to the Exchange server. When I unlock the computer, Outlook is logged out of Exchange and prompts me for credentials (although usually I have to restart Outlook to get it to reconnect). The network connection is still active, e.g. other applications don't lose their connection to the network or Internet when Windows 7 puts the display to sleep. I'm using a Dell E5400 notebook running Windows 7 Enterprise 64-bit with Outlook 2007 connecting to a corporate Exchange server (not sure if it's Exchange 2007 or 2010). The Dell is typically docked and connected via DVI (through the dock) to two Dell monitors. The Power Options in Windows 7 are set as follows: Turn Off The Display: 15 minutes Put The Computer To Sleep: never Those are the "Plugged In" settings but the problematic behavior is the same when running on battery. When Windows 7 turns off the display, it automatically locks the computer. E.g., I have to re-enter my credentials to access the machine. This is per corporate policy. The equivalent set up on my previous Dell notebook running Windows XP SP3 did not result in this problem with Outlook 2007 or Office Communicator 2005 connecting the very same exchange server. The problem began when I switched to the new Dell E5400 with Windows 7.

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  • Does your organization still use the term "screens" to describe a user interface?

    - by bit-twiddler
    I have been in the field long enough to remember when the term "screen" entered our lexicon. As difficult as it is to believe, the early systems on which I worked had no user interface (UI), that is, unless one counts a keypunch machine and job listings as a user interface. These systems ran as "card image" production jobs back in a day when being a computer operator required a reasonably deep understanding of how computers worked. Flashing forward to today: I cringe every time I hear a systems practitioner use the term "screen." The metaphor no longer fits the medium. The term somewhat fit back when the user dialog consumed 100% of available monitor real estate; however, the term lost its relevance the moment we moved to windowed environments. With the above said, does your organization still use the term "screens" to describe an application's UI? Has anyone successfully purged the term from an organization? For those who do not use the term to describe UI dialog elements, what term do you use in place of “screen.”

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  • The November OBIEE 11.1.1.6.6 Bundle Patch has been released

    - by inowodwo
    The November Oracle Business Intelligence Enterprise Edition - OBIEE 11.1.1.6.6 Bundle Patch is now available for download from My Oracle Support For OBIEE on 11.1.1.6.0, the plan is to run a monthly bundle patch 11.1.1.6.6 bundle patch includes 67 bug fixes. 11.1.1.6.6 bundle patch is cumulative, so it includes everything in 11.1.1.6.1, 11.1.1.6.2, 11.1.1.6.2BP1, 11.1.1.6.4 and 11.1.1.6.5. Please note that this release is only recommended for BI customers i.e. not customers on Fusion Apps Bundled Patch Details (1 of 7) Oracle Business Intelligence Installer. (patch number 15844023) (2 of 7) Oracle Real Time Decisions. (patch number 15844066) (3 of 7) Oracle Business Intelligence Publisher (patch number 14800665) (4 of 7) Oracle Business Intelligence ADF Components. (patch number 15843961) (5 of 7) Enterprise Performance Management Components Installed from BI Installer 11.1.1.6.x (patch number 15844096) (6 of 7) Oracle Business Intelligence (patch number 14791926) (7 of 7) Oracle Business Intelligence Platform Client Installers and MapViewer (patch number 15839347) 11.1.1.6.6 bundle patch is available for the supported platforms : Microsoft Windows (32-bit) Linux x86 (32-bit) Microsoft Windows x64 (64-bit) Linux x86-64 (64-bit) Oracle Solaris on SPARC (64-bit) Oracle Solaris on x86-64 (64-bit) IBM AIX PPC (64-bit) HPUX- IA (64-bit)

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  • Can I use AppDomain.AssemblyResolve Event to redirect a failed Assembly Load?

    - by esac
    By default, my application references a mixed mode DLL, so this DLL is both 32 and 64 bit. On a 32 bit system, my app is MSIL and loads the 32 bit DLL. On a 64 bit system, my app loads the 64 bit. However on a 64 bit system, in an older version of the assembly that I am referencing, they only created a 32 bit version. So I fail to load this. I was looking at doing it dynamically, and ideally I would want my MSIL app in 64 bit mode to load the 32 bit DLL. Is this possible? Also it would be nice to resolve it to a different version than what I have referenced as well. Any help appreciated.

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