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• Bitfield With 3 States...?

  - by TheCloudlessSky

  I'm trying to create an authorization scheme for my ASP.NET MVC application where an Enum is used to set permissions. For example: [Flags] enum Permissions { ReadAppointments = 1, WriteAppointments = 2 | ReadAppointments, ReadPatients = 4, WritePatients = 8 | ReadPatients, ReadInvoices = 16, WriteInvoices = 32 | ReadInvoices ... } But I don't really like that because it really doesn't make it clear that Write always includes Read. I then realized that a requirement would be that a user might have NO access to, for example, Appointments. Essentially, I'd want a "bitfield" with 3 states: none, readonly, full (read/write). I'd like to still use an enum bitfield since it's easy to store in a DB (as an int). Also it's very easy to see if a permission is set. Does anyone have any idea how this could be easily accomplished using an Enum... or am I going in the completely wrong direction?

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• Bitfield mask/operations with optional items

  - by user1560249

  I'm trying to find a way to handle several bitfield cases that include optional, required, and not allowed positions. yy?nnn?y 11000001 ?yyy?nnn 01110000 nn?yyy?n 00011100 ?nnn?yyy 00000111 In these four cases, the ? indicates that the bit can be either 1 or 0 while y indicates a 1 is required and n indicates that a 0 is required. The bits to the left/right of the required bits can be anything and the remaining bits must be 0. Is there a masking method I can use to test if an input bit set satisfies one of these cases?

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• bitfield mask calculation macro

  - by Aidan Cully

  We have a set of C macros, here, for using the preprocessor to do bitfield operations, and we run into warnings when attempting to use these macros in visual studio. The problem can be demonstrated very easily: #define BITFIELD_WIDTHMASK(Width) \ ((Width) >= 32 ? ~0x0ul : (1ul << (Width)) - 1) unsigned long foo(void) { return BITFIELD_WIDTHMASK(32); } Compiling this with MSVC yields the warning: test.c(12) : warning C4293: '<<' : shift count negative or too big, undefined behavior This isn't a behavior problem - the << operator won't be used in this case, and that should be detected at compile time. But does anyone have any suggestions about how to rewrite the macro to avoid the warning? Or, failing that, how to redesign the macro interface for this? Thanks in advance

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• Implementing a bitfield using java enums

  - by soappatrol

  Hello, I maintain a large document archive and I often use bit fields to record the status of my documents during processing or when validating them. My legacy code simply uses static int constants such as: static int DOCUMENT_STATUS_NO_STATE = 0 static int DOCUMENT_STATUS_OK = 1 static int DOCUMENT_STATUS_NO_TIF_FILE = 2 static int DOCUMENT_STATUS_NO_PDF_FILE = 4 This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example: status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE; Since the approach of using static constants is bad practice and because I would like to improve the code, I was looking to use Enums to achieve the same. There are a few requirements, one of them being the need to save the status into a database as a numeric type. So there is a need to transform the enumeration constants to a numeric value. Below is my first approach and I wonder if this is the correct way to go about this? class DocumentStatus{ public enum StatusFlag { DOCUMENT_STATUS_NOT_DEFINED(1<<0), DOCUMENT_STATUS_OK(1<<1), DOCUMENT_STATUS_MISSING_TID_DIR(1<<2), DOCUMENT_STATUS_MISSING_TIF_FILE(1<<3), DOCUMENT_STATUS_MISSING_PDF_FILE(1<<4), DOCUMENT_STATUS_MISSING_OCR_FILE(1<<5), DOCUMENT_STATUS_PAGE_COUNT_TIF(1<<6), DOCUMENT_STATUS_PAGE_COUNT_PDF(1<<7), DOCUMENT_STATUS_UNAVAILABLE(1<<8), private final long statusFlagValue; StatusFlag(long statusFlagValue) { this.statusFlagValue = statusFlagValue } public long getStatusFlagValue(){ return statusFlagValue } } /** * Translates a numeric status code into a Set of StatusFlag enums * @param numeric statusValue * @return EnumSet representing a documents status */ public EnumSet<StatusFlag> getStatusFlags(long statusValue) { EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class) StatusFlag.each { statusFlag -> long flagValue = statusFlag.statusFlagValue if ( (flagValue&statusValue ) == flagValue ) { statusFlags.add(statusFlag) } } return statusFlags } /** * Translates a set of StatusFlag enums into a numeric status code * @param Set if statusFlags * @return numeric representation of the document status */ public long getStatusValue(Set<StatusFlag> flags) { long value=0 flags.each { statusFlag -> value|=statusFlag.getStatusFlagValue() } return value } public static void main(String[] args) { DocumentStatus ds = new DocumentStatus(); Set statusFlags = EnumSet.of( StatusFlag.DOCUMENT_STATUS_OK, StatusFlag.DOCUMENT_STATUS_UNAVAILABLE) assert ds.getStatusValue( statusFlags )==258 // 0000.0001|0000.0010 long numericStatusCode = 56 statusFlags = ds.getStatusFlags(numericStatusCode) assert !statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE) } }

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• Drawbacks of using an integer as a bitfield?

  - by Mark

  I have a bunch of boolean options for things like "accepted payment types" which can include things like cash, credit card, cheque, paypal, etc. Rather than having a half dozen booleans in my DB, I can just use an integer and assign each payment method an integer, like so PAYMENT_METHODS = ( (1<<0, 'Cash'), (1<<1, 'Credit Card'), (1<<2, 'Cheque'), (1<<3, 'Other'), ) and then query the specific bit in python to retrieve the flag. I know this means the database can't index by specific flags, but are there any other drawbacks?

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• What is the best way to do Bit Field manipulation in Python?

  - by ZebZiggle

  I'm reading some MPEG Transport Stream protocol over UDP and it has some funky bitfields in it (length 13 for example). I'm using the "struct" library to do the broad unpacking, but is there a simple way to say "Grab the next 13 bits" rather than have to hand-tweak the bit manipulation? I'd like something like the way C does bit fields (without having to revert to C). Suggestions?

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• Fastest way to perform subset test operation on a large collection of sets with same domain

  - by niktech

  Assume we have trillions of sets stored somewhere. The domain for each of these sets is the same. It is also finite and discrete. So each set may be stored as a bit field (eg: 0000100111...) of a relatively short length (eg: 1024). That is, bit X in the bitfield indicates whether item X (of 1024 possible items) is included in the given set or not. Now, I want to devise a storage structure and an algorithm to efficiently answer the query: what sets in the data store have set Y as a subset. Set Y itself is not present in the data store and is specified at run time. Now the simplest way to solve this would be to AND the bitfield for set Y with bit fields of every set in the data store one by one, picking the ones whose AND result matches Y's bitfield. How can I speed this up? Is there a tree structure (index) or some smart algorithm that would allow me to perform this query without having to AND every stored set's bitfield? Are there databases that already support such operations on large collections of sets?

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• Most common C# bitwise operations

  - by steffenj

  For the life of me, I can't remember how to set, delete, toggle or test a bit in a bitfield. Either I'm unsure or I mix them up because I rarely need these. So a "bit-cheat-sheet" would be nice to have. For example: flags = flags | FlagsEnum.Bit4; // Set bit 4. or if ((flags == FlagsEnum.Bit4)) == FlagsEnum.Bit4) // Is there a less verbose way? Can you give examples of all the other common operations, preferably in C# syntax using a [Flags] enum?

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• Best way to store weekly event in MySQL?

  - by mazin k.

  I have a table of weekly events that run on certain days of the week (e.g. MTWTh, MWF, etc.) and run on a certain time (e.g. 8am-5pm). What's the best way to store day of week information in MySQL to make retrieving and working with the data easiest? My CakePHP app is going to need to retrieve all events happening NOW(). For time of day, I would just use TIME. For days of the week, I had considered a 7-bit bitfield, a varchar ("MTWThFr" type deal) for the days of the week, but both of those seem like clunky solutions (the varchar being clunkier). Any suggestions?

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• Codeigniter: State Machine how to

  - by Kevin Brown

  I created a db row called "activity_state" to denote which things a user has and hasn't completed. The problem is, I don't know how to use it... How can I use this single row to determine what a user has done? ie. have they completed their profile?, have they completed an assignment? Someone mentioned using it as a bitfield, but I'm unfamiliar with that. Is that a good idea? Any ideas?

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• Windows 8.1 IRQL_NOT_LESS_OR_EQUAL with Asus PCE-n53

  - by JArsenault89

  I saw the following question, and it is the exact same problem on my machine, I have tracked it to the ASUS PCE-n53 wireless card in my desktop. Does anyone know of a workaround? Windows 8.1 RTM installation crashes The adapter worked fine in windows 8... any ideas? EDIT: Crash Dump Analysis * Bugcheck Analysis * * IRQL_NOT_LESS_OR_EQUAL (a) An attempt was made to access a pageable (or completely invalid) address at an interrupt request level (IRQL) that is too high. This is usually caused by drivers using improper addresses. If a kernel debugger is available get the stack backtrace. Arguments: Arg1: 0000000000000000, memory referenced Arg2: 0000000000000002, IRQL Arg3: 0000000000000001, bitfield : bit 0 : value 0 = read operation, 1 = write operation bit 3 : value 0 = not an execute operation, 1 = execute operation (only on chips which support this level of status) Arg4: fffff801ef4f1316, address which referenced memory Debugging Details: WRITE_ADDRESS: 0000000000000000 CURRENT_IRQL: 2 FAULTING_IP: nt!KeReleaseSpinLock+16 fffff801`ef4f1316 f048832100 lock and qword ptr [rcx],0 DEFAULT_BUCKET_ID: WIN8_DRIVER_FAULT BUGCHECK_STR: AV PROCESS_NAME: System ANALYSIS_VERSION: 6.3.9600.16384 (debuggers(dbg).130821-1623) amd64fre TRAP_FRAME: ffffd00020d45550 -- (.trap 0xffffd00020d45550) NOTE: The trap frame does not contain all registers. Some register values may be zeroed or incorrect. rax=0000000000000001 rbx=0000000000000000 rcx=0000000000000000 rdx=0000000055920200 rsi=0000000000000000 rdi=0000000000000000 rip=fffff801ef4f1316 rsp=ffffd00020d456e0 rbp=ffffd00020d45768 r8=0000000055920222 r9=0000000035930000 r10=0000000055920222 r11=ffffd00020d456a8 r12=0000000000000000 r13=0000000000000000 r14=0000000000000000 r15=0000000000000000 iopl=0 nv up ei pl zr na po nc nt!KeReleaseSpinLock+0x16: fffff801ef4f1316 f048832100 lock and qword ptr [rcx],0 ds:0000000000000000=???????????????? Resetting default scope LOCK_ADDRESS: fffff801ef6da360 -- (!locks fffff801ef6da360) Resource @ nt!PiEngineLock (0xfffff801ef6da360) Exclusively owned Contention Count = 6 Threads: ffffe000010ff040-01<* 1 total locks, 1 locks currently held PNP_TRIAGE: Lock address : 0xfffff801ef6da360 Thread Count : 1 Thread address: 0xffffe000010ff040 Thread wait : 0x1fbe LAST_CONTROL_TRANSFER: from fffff801ef5647e9 to fffff801ef558ca0 STACK_TEXT: ffffd00020d45408 fffff801ef5647e9 : 000000000000000a 0000000000000000 0000000000000002 0000000000000001 : nt!KeBugCheckEx ffffd00020d45410 fffff801ef56303a : 0000000000000001 0000000000000000 ffff0c83e3e25300 ffffd00020d45550 : nt!KiBugCheckDispatch+0x69 ffffd00020d45550 fffff801ef4f1316 : 00000000000a5890 0000000000000001 0000000000000000 ffffe00004c00000 : nt!KiPageFault+0x23a ffffd00020d456e0 fffff80003b430ad : 00000000000afe80 ffffe00004c00000 00000000000a2f80 0000000035720000 : nt!KeReleaseSpinLock+0x16 ffffd00020d45710 fffff80003ac249f : ffffe00004c00000 00000000000000a8 ffffe00004c85050 0000000000000800 : netr28x+0x840ad ffffd00020d457b0 fffff80000b76475 : ffffd00020d459e8 ffffd00020d459f0 ffffe00004ac2006 ffffe00004ac21a0 : netr28x+0x349f ffffd00020d459a0 fffff80000baa248 : ffffe00004ac2eb8 0000000000000000 ffffe00000000000 ffffe00004ac21a0 : ndis!ndisMInvokeInitialize+0x39 ffffd00020d459e0 fffff80000b74784 : 0000000000000050 ffffe00004907ba0 0000000000000000 01cecbbc328e6cde : ndis!ndisMInitializeAdapter+0x4dc ffffd00020d46050 fffff80000b74d3d : 0000000000000050 ffffe0000443e770 ffffc00000951480 ffffe00004ac21a0 : ndis!ndisInitializeAdapter+0x60 ffffd00020d460a0 fffff80000b74c14 : ffffe00004ac21a0 ffffe00004ac2050 ffffe000047ec2a0 0000000000000000 : ndis!ndisPnPStartDevice+0x89 ffffd00020d460f0 fffff80000b87695 : ffffe00004ac21a0 ffffe00004ac21a0 ffffd00020d461b0 ffffe000047ec2a0 : ndis!ndisStartDeviceSynchronous+0x58 ffffd00020d46140 fffff80000b6a760 : ffffe000047ec2a0 ffffe00004ac21a0 0000000000000000 0000000000000000 : ndis!ndisPnPIrpStartDevice+0x13471 ffffd00020d46170 fffff8000032576c : ffffe00004b11501 ffffe00004b11570 0000000000000001 fffff80000325880 : ndis!ndisPnPDispatch+0x140 ffffd00020d461e0 fffff8000030b40a : ffffe000047ec2a0 0000000000000106 ffffd00020d462f0 ffffe00004b116c0 : Wdf01000!FxPkgFdo::PnpSendStartDeviceDownTheStackOverload+0xe8 ffffd00020d46250 fffff80000305942 : 0000000000000106 ffffd00020d462f0 0000000000000105 ffffd00020d464d0 : Wdf01000!FxPkgPnp::PnpEventInitStarting+0xa ffffd00020d46280 fffff80000305a5a : ffffe00004b116c8 0000000000000002 ffffe00004b11570 ffffe00004b11600 : Wdf01000!FxPkgPnp::PnpEnterNewState+0x102 ffffd00020d46310 fffff80000305bc4 : 0000000000000000 ffffd00020d46400 ffffe00004b116a0 0000000000000000 : Wdf01000!FxPkgPnp::PnpProcessEventInner+0xc2 ffffd00020d46390 fffff8000030c27a : 0000000000000000 ffffe00004b11570 0000000000000000 ffffe00004b11570 : Wdf01000!FxPkgPnp::PnpProcessEvent+0xe4 ffffd00020d46430 fffff80000300936 : ffffe00004b11570 ffffd00020d464c0 0000000000000000 ffffe00004a0e630 : Wdf01000!FxPkgPnp::_PnpStartDevice+0x1e ffffd00020d46460 fffff800002fba18 : ffffe000047ec2a0 ffffe000047ec2a0 0000000000000000 ffffe0000486f020 : Wdf01000!FxPkgPnp::Dispatch+0xd2 ffffd00020d464d0 fffff801ef838796 : 0000000000000000 fffff801ef6aa101 0000000000000000 ffffd000208aa180 : Wdf01000!FxDevice::DispatchWithLock+0x7d8 ffffd00020d465b0 fffff801ef4d5bad : ffffe000011dc3a0 ffffd00020d46659 0000000000000000 fffff801ef7f5ba4 : nt!PnpAsynchronousCall+0x102 ffffd00020d465f0 fffff801ef838e57 : ffffe000011db8d0 ffffe000011db8d0 ffffe00004a8d060 ffffc00002b11200 : nt!PnpStartDevice+0xc5 ffffd00020d466c0 fffff801ef838fe7 : ffffe000011db8d0 ffffe000011db8d0 0000000000000000 ffffe000011db8d0 : nt!PnpStartDeviceNode+0x147 ffffd00020d46790 fffff801ef7fd19e : ffffe000011db8d0 0000000000000001 0000000000000001 ffffe00000000001 : nt!PipProcessStartPhase1+0x53 ffffd00020d467d0 fffff801ef897b17 : ffffe000011db8d0 0000000000000001 0000000000000000 fffff801ef7ef7b2 : nt!PipProcessDevNodeTree+0x3ce ffffd00020d46a50 fffff801ef4f5033 : 0000000100000003 0000000000000000 0000000000000000 0000000000000000 : nt!PiRestartDevice+0xaf ffffd00020d46aa0 fffff801ef44565d : fffff801ef4f4c90 ffffd00020d46bd0 0000000000000000 ffffe00004a10170 : nt!PnpDeviceActionWorker+0x3a3 ffffd00020d46b50 fffff801ef4eec80 : 0000000000000000 ffffe000010ff040 ffffe000010ff040 ffffe0000035c900 : nt!ExpWorkerThread+0x2b5 ffffd00020d46c00 fffff801ef55f2c6 : ffffd00020472180 ffffe000010ff040 ffffe00000608040 ffffc00000002710 : nt!PspSystemThreadStartup+0x58 ffffd00020d46c60 0000000000000000 : ffffd00020d47000 ffffd00020d41000 0000000000000000 0000000000000000 : nt!KiStartSystemThread+0x16 STACK_COMMAND: kb FOLLOWUP_IP: netr28x+840ad fffff800`03b430ad 4533e4 xor r12d,r12d SYMBOL_STACK_INDEX: 4 SYMBOL_NAME: netr28x+840ad FOLLOWUP_NAME: MachineOwner MODULE_NAME: netr28x IMAGE_NAME: netr28x.sys DEBUG_FLR_IMAGE_TIMESTAMP: 51de7a8d FAILURE_BUCKET_ID: AV_netr28x+840ad BUCKET_ID: AV_netr28x+840ad ANALYSIS_SOURCE: KM FAILURE_ID_HASH_STRING: km:av_netr28x+840ad FAILURE_ID_HASH: {a1f86ced-f566-ac23-afeb-1aa88ea5ab8f} Followup: MachineOwner

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• HP ProLiant DL380 G3 Running Windows Server 2000 has crashed between 6-7:30am for the past 5 days

  - by user109717

  I have a HP ProLiant DL380 G3 running Windows Server 2000 that has been crashing everyday between 6-730am. This started when I changed out a failing hard drive 6 days ago. I have looked at the scheduled tasks which does not have anything pertaining to this issue. Below are the only things I see in the system log and some of the dump files. Can this be a hardware issue if this happens at a certain time frame everyday? Any help is greatly appreciated. Thanks The previous system shutdown at 6:07:55 AM on 2/7/2012 was unexpected. System Information Agent: Health: The server is operational again. The server has previously been shutdown by the Automatic Server Recovery (ASR) feature and has just become operational again. [SNMP TRAP: 6025 in CPQHLTH.MIB] BugCheck 7A, {3, c0000005, 3400028, 0} Probably caused by : memory_corruption ( nt!MiMakeSystemAddressValidPfn+42 ) Followup: MachineOwner 0: kd !analyze -v * Bugcheck Analysis * * KERNEL_DATA_INPAGE_ERROR (7a) The requested page of kernel data could not be read in. Typically caused by a bad block in the paging file or disk controller error. Also see KERNEL_STACK_INPAGE_ERROR. If the error status is 0xC000000E, 0xC000009C, 0xC000009D or 0xC0000185, it means the disk subsystem has experienced a failure. If the error status is 0xC000009A, then it means the request failed because a filesystem failed to make forward progress. Arguments: Arg1: 00000003, lock type that was held (value 1,2,3, or PTE address) Arg2: c0000005, error status (normally i/o status code) Arg3: 03400028, current process (virtual address for lock type 3, or PTE) Arg4: 00000000, virtual address that could not be in-paged (or PTE contents if arg1 is a PTE address) MODULE_NAME: nt IMAGE_NAME: memory_corruption BugCheck A, {0, 2, 1, 804137d6} Probably caused by : ntkrnlmp.exe ( nt!CcGetVirtualAddress+ba ) * Bugcheck Analysis * * IRQL_NOT_LESS_OR_EQUAL (a) An attempt was made to access a pageable (or completely invalid) address at an interrupt request level (IRQL) that is too high. This is usually caused by drivers using improper addresses. If a kernel debugger is available get the stack backtrace. Arguments: Arg1: 00000000, memory referenced Arg2: 00000002, IRQL Arg3: 00000001, bitfield : bit 0 : value 0 = read operation, 1 = write operation bit 3 : value 0 = not an execute operation, 1 = execute operation (only on chips which support this level of status) Arg4: 804137d6, address which referenced memory MODULE_NAME: nt IMAGE_NAME: ntkrnlmp.exe

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