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  • How do I unpack bits from a structure's stream_data in c code?

    - by Chelp
    Ex. typedef struct { bool streamValid; dword dateTime; dword timeStamp; stream_data[800]; } RadioDataA; Ex. Where stream_data[800] contains: **Variable** **Length (in bits)** packetID 8 packetL 8 versionMajor 4 versionMinor 4 radioID 8 etc.. I need to write: void unpackData(radioDataA *streamData, MA_DataA *maData) { //unpack streamData (from above) & put some of the data into maData //How do I read in bits of data? I know it's by groups of 8 but I don't understand how. //MAData is also a struct. }

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  • Segmentation fault in a function to reverse a singly linked list recursivley.

    - by Amanda
    I am implementing a function to recursively reverse a linked-list, but getting seg-fault. typedef struct _node { int data; struct _node *next; } Node, *NodeP; NodeP recursiveReverseList(NodeP first){ if(first == NULL) return NULL; if(first->next == NULL) return first; NodeP rest = recursiveReverseList(first->next); rest->next = first; first->next = NULL; return first; } Can you please help? P.S. The iterative version is working fine though. Its not homework. Just practicing C. Thank you all :)

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  • Why does a non-constant offsetof expression work?

    - by Chris J. Kiick
    Why does this work: #include <sys/types.h> #include <stdio.h> #include <stddef.h> typedef struct x { int a; int b[128]; } x_t; int function(int i) { size_t a; a = offsetof(x_t, b[i]); return a; } int main(int argc, char **argv) { printf("%d\n", function(atoi(argv[1]))); } If I remember the definition of offsetof correctly, it's a compile time construct. Using 'i' as the array index results in a non-constant expression. I don't understand how the compiler can evaluate the expression at compile time. Why isn't this flagged as an error?

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  • Do c++ templates make programs slow ?

    - by user293398
    Hi, I have heard from many people that usage of templates make the code slow. Is it really true. I'm currently building a library. There are places where if templates are not created, it would result in code management problem. As of now I can think two solutions to this problem: o use #defines o Use templates and define all possible types in the header file/library itself but do not allow end user to make template instances. e.g. typedef Graph GraphI32; etc. Is there anyway, to restrict user from creating various template instances on their own. Help on above queries would be highly regarded.

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  • How to cast correctly a struct in C++

    - by kriau
    Consider a code excerpt below: typedef struct tagTHREADNAME_INFO { DWORD dwType; LPCTSTR szName; DWORD dwThreadID; DWORD dwFlags; } THREADNAME_INFO; const THREADNAME_INFO info = { 0x1000, threadName, CurrentId(), 0}; ::RaiseException(kVCThreadNameException, 0, sizeof(info) / sizeof(ULONG_PTR), (ULONG_PTR*)&info); How to cast correctly into ULONG_PTR* using C++ style cast? p.s. it's platform dependent code.

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  • Windows C++: LPCTSTR vs const TCHAR

    - by mrl33t
    In my application i'm declaring a string variable near the top of my code to define the name of my window class which I use in my calls to RegisterClassEx, CreateWindowEx etc.. Now, I know that an LPCTSTR is a typedef and will eventually follow down to a TCHAR (well a CHAR or WCHAR depending on whether UNICODE is defined), but I was wondering whether it would be better to use this: static LPCTSTR szWindowClass = TEXT("MyApp"); Or this: static const TCHAR szWindowClass[] = TEXT("MyApp"); I personally prefer the use of the LPCTSTR as coming from a JavaScript, PHP, C# background I never really considered declaring a string as an array of chars. But are there actually any advantages of using one over the other, or does it in fact not even make a difference as to which one I choose? Thank you, in advanced, for your answers.

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  • *(char**) how to understand this construct?

    - by House.Lee
    recently, while reading former's code in my current project, I encounter the problems below: while implementing the Queue, my former wrote codes like this: while(uq->pHead) { char *tmp = uq->pHead; uq->pHead = *(char **)tmp; //... } the uq-pHead has definition like: typedef struct { char* pHead; //... } Queue; Well, I'm quite confused about the usage that "uq->pHead = *(char**)tmp" , could anyone explain it to me in detail? if we assume that *(uq-pHead) = 32(i.e. ' ') , *(char**)tmp would translate this into pointer-form, but...how could it make sense? Thanks a lot.

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  • Will the template argument's destructor to a templated class be called on deletion?

    - by Mutmansky
    If you have a templated base class as in the following example: class A{ A(); virtual ~A(); }; template <class T> class B : public T { B(); virtual ~B(); }; typedef B<A> C; class D : public C { D(); virtual ~D(); }; When you delete an instance of D, will the destructor of A be called? I'll probably create a test program to find out what happens, but just thinking about it, I wasn't sure what should happen.

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  • Structs and pointers

    - by user1763861
    I have a few questions about structs and pointers For this struct: typedef struct tNode_t { char *w; } tNode; How come if I want to change/know the value of *w I need to use t.w = "asdfsd" instead of t->w = "asdfasd"? And I compiled this successfully without having t.w = (char *) malloc(28*sizeof(char)); in my testing code, is there a reason why tt's not needed? Sample main: int main() { tNode t; char w[] = "abcd"; //t.word = (char *) malloc(28*sizeof(char)); t.word = w; printf("%s", t.word); } Thanks.

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  • referencing struct fields in c with square brackets and an index instead of . and ->?

    - by lsiebert
    Assuming I have a structure such as: typedef struct { char * string1; char * string2; } TWO_WORDS; such that all the fields are of the same type, and my main has TWO_WORDS tw; can I reference string1 with tw[0] and string2 with two[1]? If so: is this part of the c standard? do i have to cast the struct to an array first? what about fields which are different sizes in memory what about fields which are different types but the same size? can you do pointer arithmetic within a structure? -

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  • Ancillary Objects: Separate Debug ELF Files For Solaris

    - by Ali Bahrami
    We introduced a new object ELF object type in Solaris 11 Update 1 called the Ancillary Object. This posting describes them, using material originally written during their development, the PSARC arc case, and the Solaris Linker and Libraries Manual. ELF objects contain allocable sections, which are mapped into memory at runtime, and non-allocable sections, which are present in the file for use by debuggers and observability tools, but which are not mapped or used at runtime. Typically, all of these sections exist within a single object file. Ancillary objects allow them to instead go into a separate file. There are different reasons given for wanting such a feature. One can debate whether the added complexity is worth the benefit, and in most cases it is not. However, one important case stands out — customers with very large 32-bit objects who are not ready or able to make the transition to 64-bits. We have customers who build extremely large 32-bit objects. Historically, the debug sections in these objects have used the stabs format, which is limited, but relatively compact. In recent years, the industry has transitioned to the powerful but verbose DWARF standard. In some cases, the size of these debug sections is large enough to push the total object file size past the fundamental 4GB limit for 32-bit ELF object files. The best, and ultimately only, solution to overly large objects is to transition to 64-bits. However, consider environments where: Hundreds of users may be executing the code on large shared systems. (32-bits use less memory and bus bandwidth, and on sparc runs just as fast as 64-bit code otherwise). Complex finely tuned code, where the original authors may no longer be available. Critical production code, that was expensive to qualify and bring online, and which is otherwise serving its intended purpose without issue. Users in these risk adverse and/or high scale categories have good reasons to push 32-bits objects to the limit before moving on. Ancillary objects offer these users a longer runway. Design The design of ancillary objects is intended to be simple, both to help human understanding when examining elfdump output, and to lower the bar for debuggers such as dbx to support them. The primary and ancillary objects have the same set of section headers, with the same names, in the same order (i.e. each section has the same index in both files). A single added section of type SHT_SUNW_ANCILLARY is added to both objects, containing information that allows a debugger to identify and validate both files relative to each other. Given one of these files, the ancillary section allows you to identify the other. Allocable sections go in the primary object, and non-allocable ones go into the ancillary object. A small set of non-allocable objects, notably the symbol table, are copied into both objects. As noted above, most sections are only written to one of the two objects, but both objects have the same section header array. The section header in the file that does not contain the section data is tagged with the SHF_SUNW_ABSENT section header flag to indicate its placeholder status. Compiler writers and others who produce objects can set the SUNW_SHF_PRIMARY section header flag to mark non-allocable sections that should go to the primary object rather than the ancillary. If you don't request an ancillary object, the Solaris ELF format is unchanged. Users who don't use ancillary objects do not pay for the feature. This is important, because they exist to serve a small subset of our users, and must not complicate the common case. If you do request an ancillary object, the runtime behavior of the primary object will be the same as that of a normal object. There is no added runtime cost. The primary and ancillary object together represent a logical single object. This is facilitated by the use of a single set of section headers. One can easily imagine a tool that can merge a primary and ancillary object into a single file, or the reverse. (Note that although this is an interesting intellectual exercise, we don't actually supply such a tool because there's little practical benefit above and beyond using ld to create the files). Among the benefits of this approach are: There is no need for per-file symbol tables to reflect the contents of each file. The same symbol table that would be produced for a standard object can be used. The section contents are identical in either case — there is no need to alter data to accommodate multiple files. It is very easy for a debugger to adapt to these new files, and the processing involved can be encapsulated in input/output routines. Most of the existing debugger implementation applies without modification. The limit of a 4GB 32-bit output object is now raised to 4GB of code, and 4GB of debug data. There is also the future possibility (not currently supported) to support multiple ancillary objects, each of which could contain up to 4GB of additional debug data. It must be noted however that the 32-bit DWARF debug format is itself inherently 32-bit limited, as it uses 32-bit offsets between debug sections, so the ability to employ multiple ancillary object files may not turn out to be useful. Using Ancillary Objects (From the Solaris Linker and Libraries Guide) By default, objects contain both allocable and non-allocable sections. Allocable sections are the sections that contain executable code and the data needed by that code at runtime. Non-allocable sections contain supplemental information that is not required to execute an object at runtime. These sections support the operation of debuggers and other observability tools. The non-allocable sections in an object are not loaded into memory at runtime by the operating system, and so, they have no impact on memory use or other aspects of runtime performance no matter their size. For convenience, both allocable and non-allocable sections are normally maintained in the same file. However, there are situations in which it can be useful to separate these sections. To reduce the size of objects in order to improve the speed at which they can be copied across wide area networks. To support fine grained debugging of highly optimized code requires considerable debug data. In modern systems, the debugging data can easily be larger than the code it describes. The size of a 32-bit object is limited to 4 Gbytes. In very large 32-bit objects, the debug data can cause this limit to be exceeded and prevent the creation of the object. To limit the exposure of internal implementation details. Traditionally, objects have been stripped of non-allocable sections in order to address these issues. Stripping is effective, but destroys data that might be needed later. The Solaris link-editor can instead write non-allocable sections to an ancillary object. This feature is enabled with the -z ancillary command line option. $ ld ... -z ancillary[=outfile] ...By default, the ancillary file is given the same name as the primary output object, with a .anc file extension. However, a different name can be provided by providing an outfile value to the -z ancillary option. When -z ancillary is specified, the link-editor performs the following actions. All allocable sections are written to the primary object. In addition, all non-allocable sections containing one or more input sections that have the SHF_SUNW_PRIMARY section header flag set are written to the primary object. All remaining non-allocable sections are written to the ancillary object. The following non-allocable sections are written to both the primary object and ancillary object. .shstrtab The section name string table. .symtab The full non-dynamic symbol table. .symtab_shndx The symbol table extended index section associated with .symtab. .strtab The non-dynamic string table associated with .symtab. .SUNW_ancillary Contains the information required to identify the primary and ancillary objects, and to identify the object being examined. The primary object and all ancillary objects contain the same array of sections headers. Each section has the same section index in every file. Although the primary and ancillary objects all define the same section headers, the data for most sections will be written to a single file as described above. If the data for a section is not present in a given file, the SHF_SUNW_ABSENT section header flag is set, and the sh_size field is 0. This organization makes it possible to acquire a full list of section headers, a complete symbol table, and a complete list of the primary and ancillary objects from either of the primary or ancillary objects. The following example illustrates the underlying implementation of ancillary objects. An ancillary object is created by adding the -z ancillary command line option to an otherwise normal compilation. The file utility shows that the result is an executable named a.out, and an associated ancillary object named a.out.anc. $ cat hello.c #include <stdio.h> int main(int argc, char **argv) { (void) printf("hello, world\n"); return (0); } $ cc -g -zancillary hello.c $ file a.out a.out.anc a.out: ELF 32-bit LSB executable 80386 Version 1 [FPU], dynamically linked, not stripped, ancillary object a.out.anc a.out.anc: ELF 32-bit LSB ancillary 80386 Version 1, primary object a.out $ ./a.out hello worldThe resulting primary object is an ordinary executable that can be executed in the usual manner. It is no different at runtime than an executable built without the use of ancillary objects, and then stripped of non-allocable content using the strip or mcs commands. As previously described, the primary object and ancillary objects contain the same section headers. To see how this works, it is helpful to use the elfdump utility to display these section headers and compare them. The following table shows the section header information for a selection of headers from the previous link-edit example. Index Section Name Type Primary Flags Ancillary Flags Primary Size Ancillary Size 13 .text PROGBITS ALLOC EXECINSTR ALLOC EXECINSTR SUNW_ABSENT 0x131 0 20 .data PROGBITS WRITE ALLOC WRITE ALLOC SUNW_ABSENT 0x4c 0 21 .symtab SYMTAB 0 0 0x450 0x450 22 .strtab STRTAB STRINGS STRINGS 0x1ad 0x1ad 24 .debug_info PROGBITS SUNW_ABSENT 0 0 0x1a7 28 .shstrtab STRTAB STRINGS STRINGS 0x118 0x118 29 .SUNW_ancillary SUNW_ancillary 0 0 0x30 0x30 The data for most sections is only present in one of the two files, and absent from the other file. The SHF_SUNW_ABSENT section header flag is set when the data is absent. The data for allocable sections needed at runtime are found in the primary object. The data for non-allocable sections used for debugging but not needed at runtime are placed in the ancillary file. A small set of non-allocable sections are fully present in both files. These are the .SUNW_ancillary section used to relate the primary and ancillary objects together, the section name string table .shstrtab, as well as the symbol table.symtab, and its associated string table .strtab. It is possible to strip the symbol table from the primary object. A debugger that encounters an object without a symbol table can use the .SUNW_ancillary section to locate the ancillary object, and access the symbol contained within. The primary object, and all associated ancillary objects, contain a .SUNW_ancillary section that allows all the objects to be identified and related together. $ elfdump -T SUNW_ancillary a.out a.out.anc a.out: Ancillary Section: .SUNW_ancillary index tag value [0] ANC_SUNW_CHECKSUM 0x8724 [1] ANC_SUNW_MEMBER 0x1 a.out [2] ANC_SUNW_CHECKSUM 0x8724 [3] ANC_SUNW_MEMBER 0x1a3 a.out.anc [4] ANC_SUNW_CHECKSUM 0xfbe2 [5] ANC_SUNW_NULL 0 a.out.anc: Ancillary Section: .SUNW_ancillary index tag value [0] ANC_SUNW_CHECKSUM 0xfbe2 [1] ANC_SUNW_MEMBER 0x1 a.out [2] ANC_SUNW_CHECKSUM 0x8724 [3] ANC_SUNW_MEMBER 0x1a3 a.out.anc [4] ANC_SUNW_CHECKSUM 0xfbe2 [5] ANC_SUNW_NULL 0 The ancillary sections for both objects contain the same number of elements, and are identical except for the first element. Each object, starting with the primary object, is introduced with a MEMBER element that gives the file name, followed by a CHECKSUM that identifies the object. In this example, the primary object is a.out, and has a checksum of 0x8724. The ancillary object is a.out.anc, and has a checksum of 0xfbe2. The first element in a .SUNW_ancillary section, preceding the MEMBER element for the primary object, is always a CHECKSUM element, containing the checksum for the file being examined. The presence of a .SUNW_ancillary section in an object indicates that the object has associated ancillary objects. The names of the primary and all associated ancillary objects can be obtained from the ancillary section from any one of the files. It is possible to determine which file is being examined from the larger set of files by comparing the first checksum value to the checksum of each member that follows. Debugger Access and Use of Ancillary Objects Debuggers and other observability tools must merge the information found in the primary and ancillary object files in order to build a complete view of the object. This is equivalent to processing the information from a single file. This merging is simplified by the primary object and ancillary objects containing the same section headers, and a single symbol table. The following steps can be used by a debugger to assemble the information contained in these files. Starting with the primary object, or any of the ancillary objects, locate the .SUNW_ancillary section. The presence of this section identifies the object as part of an ancillary group, contains information that can be used to obtain a complete list of the files and determine which of those files is the one currently being examined. Create a section header array in memory, using the section header array from the object being examined as an initial template. Open and read each file identified by the .SUNW_ancillary section in turn. For each file, fill in the in-memory section header array with the information for each section that does not have the SHF_SUNW_ABSENT flag set. The result will be a complete in-memory copy of the section headers with pointers to the data for all sections. Once this information has been acquired, the debugger can proceed as it would in the single file case, to access and control the running program. Note - The ELF definition of ancillary objects provides for a single primary object, and an arbitrary number of ancillary objects. At this time, the Oracle Solaris link-editor only produces a single ancillary object containing all non-allocable sections. This may change in the future. Debuggers and other observability tools should be written to handle the general case of multiple ancillary objects. ELF Implementation Details (From the Solaris Linker and Libraries Guide) To implement ancillary objects, it was necessary to extend the ELF format to add a new object type (ET_SUNW_ANCILLARY), a new section type (SHT_SUNW_ANCILLARY), and 2 new section header flags (SHF_SUNW_ABSENT, SHF_SUNW_PRIMARY). In this section, I will detail these changes, in the form of diffs to the Solaris Linker and Libraries manual. Part IV ELF Application Binary Interface Chapter 13: Object File Format Object File Format Edit Note: This existing section at the beginning of the chapter describes the ELF header. There's a table of object file types, which now includes the new ET_SUNW_ANCILLARY type. e_type Identifies the object file type, as listed in the following table. NameValueMeaning ET_NONE0No file type ET_REL1Relocatable file ET_EXEC2Executable file ET_DYN3Shared object file ET_CORE4Core file ET_LOSUNW0xfefeStart operating system specific range ET_SUNW_ANCILLARY0xfefeAncillary object file ET_HISUNW0xfefdEnd operating system specific range ET_LOPROC0xff00Start processor-specific range ET_HIPROC0xffffEnd processor-specific range Sections Edit Note: This overview section defines the section header structure, and provides a high level description of known sections. It was updated to define the new SHF_SUNW_ABSENT and SHF_SUNW_PRIMARY flags and the new SHT_SUNW_ANCILLARY section. ... sh_type Categorizes the section's contents and semantics. Section types and their descriptions are listed in Table 13-5. sh_flags Sections support 1-bit flags that describe miscellaneous attributes. Flag definitions are listed in Table 13-8. ... Table 13-5 ELF Section Types, sh_type NameValue . . . SHT_LOSUNW0x6fffffee SHT_SUNW_ancillary0x6fffffee . . . ... SHT_LOSUNW - SHT_HISUNW Values in this inclusive range are reserved for Oracle Solaris OS semantics. SHT_SUNW_ANCILLARY Present when a given object is part of a group of ancillary objects. Contains information required to identify all the files that make up the group. See Ancillary Section. ... Table 13-8 ELF Section Attribute Flags NameValue . . . SHF_MASKOS0x0ff00000 SHF_SUNW_NODISCARD0x00100000 SHF_SUNW_ABSENT0x00200000 SHF_SUNW_PRIMARY0x00400000 SHF_MASKPROC0xf0000000 . . . ... SHF_SUNW_ABSENT Indicates that the data for this section is not present in this file. When ancillary objects are created, the primary object and any ancillary objects, will all have the same section header array, to facilitate merging them to form a complete view of the object, and to allow them to use the same symbol tables. Each file contains a subset of the section data. The data for allocable sections is written to the primary object while the data for non-allocable sections is written to an ancillary file. The SHF_SUNW_ABSENT flag is used to indicate that the data for the section is not present in the object being examined. When the SHF_SUNW_ABSENT flag is set, the sh_size field of the section header must be 0. An application encountering an SHF_SUNW_ABSENT section can choose to ignore the section, or to search for the section data within one of the related ancillary files. SHF_SUNW_PRIMARY The default behavior when ancillary objects are created is to write all allocable sections to the primary object and all non-allocable sections to the ancillary objects. The SHF_SUNW_PRIMARY flag overrides this behavior. Any output section containing one more input section with the SHF_SUNW_PRIMARY flag set is written to the primary object without regard for its allocable status. ... Two members in the section header, sh_link, and sh_info, hold special information, depending on section type. Table 13-9 ELF sh_link and sh_info Interpretation sh_typesh_linksh_info . . . SHT_SUNW_ANCILLARY The section header index of the associated string table. 0 . . . Special Sections Edit Note: This section describes the sections used in Solaris ELF objects, using the types defined in the previous description of section types. It was updated to define the new .SUNW_ancillary (SHT_SUNW_ANCILLARY) section. Various sections hold program and control information. Sections in the following table are used by the system and have the indicated types and attributes. Table 13-10 ELF Special Sections NameTypeAttribute . . . .SUNW_ancillarySHT_SUNW_ancillaryNone . . . ... .SUNW_ancillary Present when a given object is part of a group of ancillary objects. Contains information required to identify all the files that make up the group. See Ancillary Section for details. ... Ancillary Section Edit Note: This new section provides the format reference describing the layout of a .SUNW_ancillary section and the meaning of the various tags. Note that these sections use the same tag/value concept used for dynamic and capabilities sections, and will be familiar to anyone used to working with ELF. In addition to the primary output object, the Solaris link-editor can produce one or more ancillary objects. Ancillary objects contain non-allocable sections that would normally be written to the primary object. When ancillary objects are produced, the primary object and all of the associated ancillary objects contain a SHT_SUNW_ancillary section, containing information that identifies these related objects. Given any one object from such a group, the ancillary section provides the information needed to identify and interpret the others. This section contains an array of the following structures. See sys/elf.h. typedef struct { Elf32_Word a_tag; union { Elf32_Word a_val; Elf32_Addr a_ptr; } a_un; } Elf32_Ancillary; typedef struct { Elf64_Xword a_tag; union { Elf64_Xword a_val; Elf64_Addr a_ptr; } a_un; } Elf64_Ancillary; For each object with this type, a_tag controls the interpretation of a_un. a_val These objects represent integer values with various interpretations. a_ptr These objects represent file offsets or addresses. The following ancillary tags exist. Table 13-NEW1 ELF Ancillary Array Tags NameValuea_un ANC_SUNW_NULL0Ignored ANC_SUNW_CHECKSUM1a_val ANC_SUNW_MEMBER2a_ptr ANC_SUNW_NULL Marks the end of the ancillary section. ANC_SUNW_CHECKSUM Provides the checksum for a file in the c_val element. When ANC_SUNW_CHECKSUM precedes the first instance of ANC_SUNW_MEMBER, it provides the checksum for the object from which the ancillary section is being read. When it follows an ANC_SUNW_MEMBER tag, it provides the checksum for that member. ANC_SUNW_MEMBER Specifies an object name. The a_ptr element contains the string table offset of a null-terminated string, that provides the file name. An ancillary section must always contain an ANC_SUNW_CHECKSUM before the first instance of ANC_SUNW_MEMBER, identifying the current object. Following that, there should be an ANC_SUNW_MEMBER for each object that makes up the complete set of objects. Each ANC_SUNW_MEMBER should be followed by an ANC_SUNW_CHECKSUM for that object. A typical ancillary section will therefore be structured as: TagMeaning ANC_SUNW_CHECKSUMChecksum of this object ANC_SUNW_MEMBERName of object #1 ANC_SUNW_CHECKSUMChecksum for object #1 . . . ANC_SUNW_MEMBERName of object N ANC_SUNW_CHECKSUMChecksum for object N ANC_SUNW_NULL An object can therefore identify itself by comparing the initial ANC_SUNW_CHECKSUM to each of the ones that follow, until it finds a match. Related Other Work The GNU developers have also encountered the need/desire to support separate debug information files, and use the solution detailed at http://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html. At the current time, the separate debug file is constructed by building the standard object first, and then copying the debug data out of it in a separate post processing step, Hence, it is limited to a total of 4GB of code and debug data, just as a single object file would be. They are aware of this, and I have seen online comments indicating that they may add direct support for generating these separate files to their link-editor. It is worth noting that the GNU objcopy utility is available on Solaris, and that the Studio dbx debugger is able to use these GNU style separate debug files even on Solaris. Although this is interesting in terms giving Linux users a familiar environment on Solaris, the 4GB limit means it is not an answer to the problem of very large 32-bit objects. We have also encountered issues with objcopy not understanding Solaris-specific ELF sections, when using this approach. The GNU community also has a current effort to adapt their DWARF debug sections in order to move them to separate files before passing the relocatable objects to the linker. The details of Project Fission can be found at http://gcc.gnu.org/wiki/DebugFission. The goal of this project appears to be to reduce the amount of data seen by the link-editor. The primary effort revolves around moving DWARF data to separate .dwo files so that the link-editor never encounters them. The details of modifying the DWARF data to be usable in this form are involved — please see the above URL for details.

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  • Physics/Graphics Components

    - by Brett Powell
    I have spent the last 48 hours reading up on Object Component systems, and feel I am ready enough to start implementing it. I got the base Object and Component classes created, but now that I need to start creating the actual components I am a bit confused. When I think of them in terms of HealthComponent or something that would basically just be a property, it makes perfect sense. When it is something more general as a Physics/Graphics component, I get a bit confused. My Object class looks like this so far (If you notice any changes I should make please let me know, still new to this)... typedef unsigned int ID; class GameObject { public: GameObject(ID id, Ogre::String name = ""); ~GameObject(); ID &getID(); Ogre::String &getName(); virtual void update() = 0; // Component Functions void addComponent(Component *component); void removeComponent(Ogre::String familyName); template<typename T> T* getComponent(Ogre::String familyName) { return dynamic_cast<T*>(m_components[familyName]); } protected: // Properties ID m_ID; Ogre::String m_Name; float m_flVelocity; Ogre::Vector3 m_vecPosition; // Components std::map<std::string,Component*> m_components; std::map<std::string,Component*>::iterator m_componentItr; }; Now the problem I am running into is what would the general population put into Components such as Physics/Graphics? For Ogre (my rendering engine) the visible Objects will consist of multiple Ogre::SceneNode (possibly multiple) to attach it to the scene, Ogre::Entity (possibly multiple) to show the visible meshes, and so on. Would it be best to just add multiple GraphicComponent's to the Object and let each GraphicComponent handle one SceneNode/Entity or is the idea to have one of each Component needed? For Physics I am even more confused. I suppose maybe creating a RigidBody and keeping track of mass/interia/etc. would make sense. But I am having trouble thinking of how to actually putting specifics into a Component. Once I get a couple of these "Required" components done, I think it will make a lot more sense. As of right now though I am still a bit stumped.

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  • Set Covering : Runtime hang\error at function call in c

    - by EnthuCrazy
    I am implementing a set covering application which uses cover function int cover(set *skill_list,set *player_list,set *covering) Suppose skill_set={a,b,c,d,e}, player_list={s1,s2,s3} then output coverin ={s1,s3} where say s1={a,b,c}, s3={d,e} and s2={b,d}. Now when I am calling this function it's hanging at run (set_cover.exe stopped working). Here is my cover function: typedef struct Spst_{ void *key; set *st; }Spst; int cover(set *skill_list,set *player_list,set *covering) { Liste *member,*max_member; Spst *subset; set *intersection; void **data; int max_size; set_init(covering); //to initialize set covering initially while(skill_list->size>0&&player_list->size>0) { max_size=0; for(member=player_list->head;member!=NULL;member=member->next) { if(set_intersection(intersection,((Spst *)(member->data))->st,skill_list)!=0) return -1; if(intersection->size>max_size) { max_member=member; max_size=intersection->size; } set_destroy(intersection); //at the end of iteration } if(max_size==0) //to check for no covering return -1; subset=(Spst *)max_member->data; //to insert max subset from play list to covering set set_inselem(covering,subset); for(member=(((Spst *)max_member->data)->st->head);member!=NULL;member=member->next) //to rem elem from skill list { data=(void **)member->data; set_remelem(skill_list,data); } set_remelem(player_list,(void **)subset); //to rem subset from set of subsets play list } if(skill_list->size>0) return -1; return 0; } Now assuming I have defined three set type sets(as stated above) and calling from main as cover(skills,subsets,covering);=> runtime hang Here Please give inputs on the missing link in this or the prerequisites for a proper call to this function type required. EDIT: Assume other functions used in cover are tested and working fine.

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  • SceneManagers as systems in entity system or as a core class used by a system?

    - by Hatoru Hansou
    It seems entity systems are really popular here. Links posted by other users convinced me of the power of such system and I decided to try it. (Well, that and my original code getting messy) In my project, I originally had a SceneManager class that maintained needed logic and structures to organize the scene (QuadTree, 2D game). Before rendering I call selectRect() and pass the x,y of the camera and the width and height of the screen and then obtain a minimized list containing only visible entities ordered from back to front. Now with Systems, originally in my first attempt my Render system required to get added all entities it should handle. This may sound like the correct approach but I realized this was not efficient. Trying to optimize It I reused the SceneManager class internally in the Renderer system, but then I realized I needed methods such as selectRect() in others systems too (AI principally) and make the SceneManager accessible globally again. Currently I converted SceneManager to a system, and ended up with the following interface (only relevant methods): /// Base system interface class System { public: virtual void tick (double delta_time) = 0; // (methods to add and remove entities) }; typedef std::vector<Entity*> EntitiesVector; /// Specialized system interface to allow query the scene class SceneManager: public System { public: virtual EntitiesVector& cull () = 0; /// Sets the entity to be used as the camera and replaces previous ones. virtual void setCamera (Entity* entity) = 0; }; class SceneRenderer // Not a system { vitual void render (EntitiesVector& entities) = 0; }; Also I could not guess how to convert renderers to systems. My game separates logic updates from screen updates, my main class have a tick() method and a render() method that may not be called the same times. In my first attempt renderers were systems but they was saved in a separated manager, updated only in render() and not in tick() like all other systems. I realized that was silly and simply created a SceneRenderer interface and give up about converting them to systems, but that may be for another question. Then... something does not feel right, isn't it? If I understood correctly a system should not depend on another or even count with another system exposing an specific interface. Each system should care only about its entities, or nodes (as optimization, so they have direct references to relevant components without having to constantly call the component() or getComponent() method of the entity).

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  • Can I get a C++ Compiler to instantiate objects at compile time

    - by gam3
    I am writing some code that has a very large number of reasonably simple objects and I would like them the be created at compile time. I would think that a compiler would be able to do this, but I have not been able to figure out how. In C I could do the the following: #include <stdio.h> typedef struct data_s { int a; int b; char *c; } info; info list[] = { 1, 2, "a", 3, 4, "b", }; main() { int i; for (i = 0; i < sizeof(list)/sizeof(*list); i++) { printf("%d %s\n", i, list[i].c); } } Using #C++* each object has it constructor called rather than just being layed out in memory. #include <iostream> using std::cout; using std::endl; class Info { const int a; const int b; const char *c; public: Info(const int, const int, const char *); const int get_a() { return a; }; const int get_b() { return b; }; const char *get_c() const { return c; }; }; Info::Info(const int a, const int b, const char *c) : a(a), b(b), c(c) {}; Info list[] = { Info(1, 2, "a"), Info(3, 4, "b"), }; main() { for (int i = 0; i < sizeof(list)/sizeof(*list); i++) { cout << i << " " << list[i].get_c() << endl; } } I just don't see what information is not available for the compiler to completely instantiate these objects at compile time, so I assume I am missing something.

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  • I was stuck in implementing Simple Ftp with Winsock [migrated]

    - by user67449
    I want to implement a SimpleFtp with Winsock. But I was stuck in the maybe the file stream reading and writing. This is the Server. #include <WinSock2.h> #include <memory.h> #include <stdio.h> #include <iostream> using namespace std; #pragma comment(lib, "ws2_32.lib") #define MAX_FILE_NAME 100 #define DATA_PACK_SIZE 80*1000 // ??DataPack?????80KB #define SOCKKET_BUFFER_SIZE 80*1000 // socket??? #define FILE_BUFFER_SIZE DATA_PACK_SIZE-MAX_FILE_NAME-4*sizeof(int)-sizeof(u_long) //?????,??,??????content????? #define CONTENT_SIZE FILE_BUFFER_SIZE // DataPack?????content??? // Define a structure to hold the content of a file typedef struct FilePack{ char fName[MAX_FILE_NAME]; // File's name int fLen; // File's length int packNum; // Number of the DataPack int packLen; // DataPack's length int packCount; int contenLen; // the content length the DataPack actually holds u_long index; // ?????????? char content[CONTENT_SIZE]; // DataPack?????? }DataPack, *pDataPack; void WinsockInitial(){ WSADATA wsaData; WORD wVersionRequested; int err; wVersionRequested=MAKEWORD(2,2); err=WSAStartup(wVersionRequested, &wsaData); if(err!=0){ cout<<"Error at WSAStartup()."<<endl; exit(0); } if( LOBYTE(wsaData.wVersion)!=2 || HIBYTE(wsaData.wVersion)!=2 ){ cout<<"Error at version of Winsock. "<<endl; WSACleanup(); exit(0); } } void SockBind(SOCKET sock, int port, sockaddr_in &addrsock){ addrsock.sin_family=AF_INET; addrsock.sin_port=htons(port); addrsock.sin_addr.S_un.S_addr=htonl(INADDR_ANY); if( bind(sock, (sockaddr*)&addrsock, sizeof(addrsock)) == SOCKET_ERROR ){ cout<<"Error at bind(). Error: "<<GetLastError()<<endl; closesocket(sock); WSACleanup(); exit(0); } } void SockListen(SOCKET sock, int bak){ int err=listen(sock, bak); if(err==SOCKET_ERROR){ cout<<"Error at listen()."<<WSAGetLastError()<<endl; closesocket(sock); WSACleanup(); exit(0); } } int SockSend(DataPack &dataPack, SOCKET sock, char *sockBuf){ int bytesLeft=0, bytesSend=0; int idx=0; bytesLeft=sizeof(dataPack); // ?DataPack?????sockBuf??? memcpy(sockBuf, &dataPack, sizeof(dataPack)); while(bytesLeft>0){ bytesSend=send(sock, &sockBuf[idx], bytesLeft, 0); if(bytesSend==SOCKET_ERROR){ cout<<"Error at send()."<<endl; return 1; } bytesLeft-=bytesSend; idx+=bytesSend; } return 0; } int GetFileLen(FILE *fp){ // ?????? if(fp==NULL){ cout<<"Invalid argument. Error at GetFileLen()."<<endl; exit(0); } fseek(fp, 0, SEEK_END); int tempFileLen=ftell(fp); fseek(fp, 0, SEEK_SET); return tempFileLen; } int main(){ int err; sockaddr_in addrServ; int port=8000; // Initialize Winsock WinsockInitial(); // Create a socket SOCKET sockListen=socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if(sockListen==INVALID_SOCKET){ cout<<"Error at socket()."<<endl; WSACleanup(); return 1; } // Bind the socket. SockBind(sockListen, port, addrServ); // Listen for incoming connection requests cout<<"Waiting for incoming connection requests..."<<endl; SockListen(sockListen, 5); // Accept the connection request. sockaddr_in addrClient; int len=sizeof(addrClient); SOCKET sockConn=accept(sockListen, (sockaddr*)&addrClient, &len); if(sockConn!=INVALID_SOCKET){ cout<<"Connected to client successfully."<<endl; } // Set the buffer size of socket char sockBuf[SOCKKET_BUFFER_SIZE]; int nBuf=SOCKKET_BUFFER_SIZE; int nBufLen=sizeof(nBuf); err=setsockopt(sockConn, SOL_SOCKET, SO_SNDBUF, (char*)&nBuf, nBufLen); if(err!=0){ cout<<"Error at setsockopt(). Failed to set buffer size for socket."<<endl; exit(0); } //??????????? err = getsockopt(sockConn, SOL_SOCKET, SO_SNDBUF, (char*)&nBuf, &nBufLen); if( SOCKKET_BUFFER_SIZE != nBuf){ cout<<"Error at setsockopt(). ?socket????????"<<endl; closesocket(sockListen); closesocket(sockConn); WSACleanup(); exit(0); } //------------------------------------------------------------------------// DataPack dataPackSend; memset(&dataPackSend, 0, sizeof(dataPackSend)); int bytesRead; int bytesLeft; int bytesSend; int packCount; // Counts how many DataPack needed FILE *frp; // Used to read if(strcpy_s(dataPackSend.fName, "music.mp3")!=0){ cout<<"Error at strcpy_s()."<<endl; return 1; } // Open the file in read+binary mode err=fopen_s(&frp, dataPackSend.fName, "rb"); if(err!=0){ cout<<"Error at fopen_s()."<<endl; return 1; } char fileBuf[FILE_BUFFER_SIZE]; // Set the buffer size of File if(setvbuf(frp, fileBuf, _IONBF, FILE_BUFFER_SIZE)!=0){ cout<<"Error at setvbuf().Failed to set buffer size for file."<<endl; closesocket(sockListen); closesocket(sockConn); WSACleanup(); exit(0); } // Get file's length int fileLen=GetFileLen(frp); cout<<"File ???:"<<fileLen<<" bytes."<<endl; // Calculate how many DataPacks needed packCount=ceil( (double)fileLen/CONTENT_SIZE ); cout<<"File Length: "<<fileLen<<" "<<"Content Size: "<<CONTENT_SIZE<<endl; cout<<"???"<<packCount<<" ?DataPack"<<endl; int i=0; for(i=0; i<packCount; i++){ //?????dataPackSend????? memset(&dataPackSend, 0, sizeof(dataPackSend)); // Fill the dataPackSend if(strcpy_s(dataPackSend.fName, "abc.txt")!=0){ cout<<"Error at strcpy_s()."<<endl; return 1; } dataPackSend.packLen=DATA_PACK_SIZE; dataPackSend.fLen=fileLen; dataPackSend.packCount=packCount; if( packCount==1 ){ //??DataPack??? bytesRead=fread(fileBuf, 1, dataPackSend.fLen, frp); dataPackSend.contenLen=dataPackSend.fLen; memcpy(dataPackSend.content, fileBuf, bytesRead); dataPackSend.packNum=0; //???????DataPack // ?????dataPackSend?Client? if( SockSend(dataPackSend, sockConn, sockBuf)==0 ){ cout<<"??? "<<dataPackSend.packNum<<" ?DataPack"<<endl; } }else if( packCount>1 && i<(packCount-1) ){ // ???(???????) bytesRead=fread(fileBuf, 1, CONTENT_SIZE, frp); dataPackSend.contenLen=CONTENT_SIZE; memcpy(dataPackSend.content, fileBuf, bytesRead); dataPackSend.packNum=i; //?dataPackSend??????Client? if( SockSend(dataPackSend, sockConn, sockBuf)==0 ){ cout<<"??? "<<dataPackSend.packNum<<" ?DataPack."<<endl; } }else{ // ????? bytesRead=fread(fileBuf, 1, (dataPackSend.fLen-i*CONTENT_SIZE), frp); dataPackSend.contenLen=dataPackSend.fLen-i*CONTENT_SIZE; memcpy(dataPackSend.content, fileBuf, bytesRead); dataPackSend.packNum=i; //?dataPackSend???Client? if( SockSend(dataPackSend, sockConn, sockBuf)==0 ){ cout<<"??? "<<dataPackSend.packNum<<" ?DataPack."<<endl; } } } fclose(frp); closesocket(sockListen); closesocket(sockConn); WSACleanup(); return 0; } And this is Client. #include <WinSock2.h> #include <memory.h> #include <stdio.h> #include <iostream> using namespace std; #pragma comment(lib, "ws2_32.lib") #define MAX_FILE_NAME 100 #define DATA_PACK_SIZE 80*1000 // ??DataPack?????80KB #define SOCKKET_BUFFER_SIZE 80*1000 // socket??? #define FILE_BUFFER_SIZE DATA_PACK_SIZE-MAX_FILE_NAME-4*sizeof(int)-sizeof(u_long) //?????,??,??????content????? #define CONTENT_SIZE FILE_BUFFER_SIZE // DataPack?????content??? // Define a structure to hold the content of a file typedef struct FilePack{ char fName[MAX_FILE_NAME]; // File's name int fLen; // File's length int packNum; // Number of the DataPack int packLen; // DataPack's length int packCount; //DataPack??? int contenLen; // the content length the DataPack actually holds u_long index; // ?????????? char content[CONTENT_SIZE]; // DataPack?????? }DataPack, *pDataPack; void WinsockInitial(){ WSADATA wsaData; WORD wVersionRequested; int err; wVersionRequested=MAKEWORD(2,2); err=WSAStartup(wVersionRequested, &wsaData); if(err!=0){ cout<<"Error at WSAStartup()."<<endl; exit(0); } if( LOBYTE(wsaData.wVersion)!=2 || HIBYTE(wsaData.wVersion)!=2 ){ cout<<"Error at version of Winsock. "<<endl; WSACleanup(); exit(0); } } int SockRecv(SOCKET sock, char *sockBuf){ int bytesLeft, bytesRecv; int idx=0; bytesLeft=DATA_PACK_SIZE; while(bytesLeft>0){ bytesRecv=recv(sock, &sockBuf[idx], bytesLeft, 0); if(bytesRecv==SOCKET_ERROR){ cout<<"Error at recv()."<<endl; return 1; } bytesLeft-=bytesRecv; idx+=bytesRecv; } return 0; } int main(){ int err; sockaddr_in addrServ; int port=8000; // Initialize Winsock WinsockInitial(); // Create a socket SOCKET sockClient=socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if(sockClient==INVALID_SOCKET){ cout<<"Error at socket()."<<endl; WSACleanup(); return 1; } // Set the buffer size of socket char sockBuf[SOCKKET_BUFFER_SIZE]; int nBuf=SOCKKET_BUFFER_SIZE; int nBufLen=sizeof(nBuf); err=setsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char*)&nBuf, nBufLen); if(err!=0){ cout<<"Error at setsockopt(). Failed to set buffer size for socket."<<endl; exit(0); } //??????????? err = getsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char*)&nBuf, &nBufLen); if( SOCKKET_BUFFER_SIZE != nBuf){ cout<<"Error at getsockopt(). ?socket????????"<<endl; closesocket(sockClient); WSACleanup(); exit(0); } // Connect to the Server addrServ.sin_family=AF_INET; addrServ.sin_port=htons(port); addrServ.sin_addr.S_un.S_addr=inet_addr("127.0.0.1"); err=connect(sockClient, (sockaddr*)&addrServ, sizeof(sockaddr)); if(err==SOCKET_ERROR){ cout<<"Error at connect()."<<GetLastError()<<endl; closesocket(sockClient); WSACleanup(); return 1; }else{ cout<<"Connected to the FTP Server successfully."<<endl; } /* int i=0; int bytesRecv, bytesLeft, bytesWrite; int packCount=0, fLen=0; DataPack dataPackRecv; //?????? SockRecv(sockClient, sockBuf); memcpy(&dataPackRecv, sockBuf, sizeof(dataPackRecv)); cout<<"???? "<<dataPackRecv.packNum<<" ?DataPack."<<endl; cout<<"?DataPack??fName????: "<<dataPackRecv.fName<<endl; //??????? packCount=dataPackRecv.packCount; cout<<"?? "<<packCount<<" ?DataPack."<<endl; fLen=dataPackRecv.fLen; // Create a local file to write into FILE *fwp; err=fopen_s(&fwp, dataPackRecv.fName, "wb"); if(err!=0){ cout<<"Error at creat fopen_s(). Failed to create a local file to write into."<<endl; return 1; } // Set the buffer size of File char fileBuf[FILE_BUFFER_SIZE]; if(setvbuf(fwp, fileBuf, _IONBF, FILE_BUFFER_SIZE)!=0){ cout<<"Error at setvbuf().Failed to set buffer size for file."<<endl; memset(fileBuf, 0, sizeof(fileBuf)); closesocket(sockClient); WSACleanup(); exit(0); } //???????content???? memcpy(fileBuf, dataPackRecv.content, sizeof(dataPackRecv.content)); bytesWrite=fwrite(fileBuf, 1, sizeof(fileBuf), fwp); if(bytesWrite<sizeof(fileBuf)){ cout<<"Error at fwrite(). Failed to write the content of dataPackRecv to local file."<<endl; } //?????packCount-1????????????????? for(int i=1; i<packCount; i++){ // ????????? memset(sockBuf, 0, sizeof(sockBuf)); memset(&dataPackRecv, 0, sizeof(dataPackRecv)); memset(fileBuf, 0, sizeof(fileBuf)); SockRecv(sockClient, sockBuf); memcpy(&dataPackRecv, sockBuf, sizeof(dataPackRecv)); cout<<"???? "<<dataPackRecv.packNum<<" ?DataPack."<<endl; //???? memcpy(fileBuf, dataPackRecv.content, dataPackRecv.contenLen); bytesWrite=fwrite(fileBuf, 1, dataPackRecv.contenLen, fwp); if(bytesWrite<dataPackRecv.contenLen){ cout<<"Error at fwrite(). Failed to write the content of dataPackRecv to local file."<<endl; } } if( (i+1)==packCount ){ cout<<"??DataPack????????!"<<endl; } fclose(fwp); closesocket(sockClient); WSACleanup(); return 0;*/ }

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  • To Obtain EPOCH Time Value from a Packed BIT Structure in C [migrated]

    - by xde0037
    This is not a home assignment! We have a binary data file which has following data structure: (It is a 12 byte structure): I need to find out Epoch time value(total time value is packed in 42 bits as described below): Field-1 : Byte 1, Byte 2, + 6 Bits from Byte 3 Time-1 : 2 Bits from Byte 3 + Byte 4 Time-2 : Byte 5, Byte 6, Byte 7, Byte 8 Field-2 : Byte 9, Byte 10, Byte 11, Byte 12 For Field-1 and Field-2 I do not have issue as they can be taken out easily. I need time value in Epoch Time (long) as it has been packed in Bytes 5,6,7,8 and 3 and 4 as follows: (the bit structure for the time value is as follows): Bytes 5 to 8 (32 bit word) Packs time value bits from 0 thru 31 (byte 5 has 0 to 7 bits, byte 6 has 8 to 15, byte 7 has 16 to 23, byte 8 has 24 to 31). the remaining 10 bits of time value are packed in Bytes 3 and byte 4 as follows: byte 3 has 2 bits:32 and 33, and Byte 4 has remaining bits : 34 to 41. So total bits for time value is 42 bits, packed as above. I need to compute epoch value coming out of these 42 bits. How do I do it? I have done something like this but not sure it gives me correct value: typedef struct P_HEADER { unsigned int tmuNumber : 21; unsigned int time1 : 10; // Bits 6,7 from Byte-3 + 8 bits from Byte-4 unsigned int time2 : 32; // 32 bits: Bytes 5,6,7,8 unsigned int traceKey : 32; } __attribute__((__packed__)) P_HEADER; Then in the code : P_HEADER *header1; //get input string in hexa,etc..etc.. //parse the input with the header as : header1 = (P_HEADER *)inputBuf; // then print the header1->time1, header1->time2 .... long ttime = header1->time1|header1->time2; //?? is this the way to get values out? Any hint tip will be appreciated. Environment is : gcc 4.1, Linux Thanks in advance.

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  • program not working as expected!

    - by wilson88
    Can anyone just help spot why my program is not returning the expected output.related to my previous question.Am passing a vector by refrence, I want to see whats in the container before I copy them to another loaction.if u remove comments on loadRage, u will see bids are generated by the trader. #include <iostream> #include <vector> #include <string> #include <algorithm> #include <cstdlib> #include <iomanip> using namespace std; const int NUMSELLER = 1; const int NUMBUYER = 1; const int NUMBIDS = 20; const int MINQUANTITY = 1; const int MAXQUANTITY = 30; const int MINPRICE =100; const int MAXPRICE = 150; int s=0; int trdId; // Bid, simple container for values struct Bid { int bidId, trdId, qty, price; char type; // for sort and find. bool operator<(const Bid &other) const { return price < other.price; } bool operator==(int bidId) const { return this->bidId == bidId; } }; // alias to the list, make type consistent typedef vector<Bid> BidList; // this class generates bids! class Trader { private: int nextBidId; public: Trader(); Bid getNextBid(); Bid getNextBid(char type); // generate a number of bids void loadRange(BidList &, int size); void loadRange(BidList &, char type, int size); void setVector(); }; Trader::Trader() : nextBidId(1) {} #define RAND_RANGE(min, max) ((rand() % (max-min+1)) + min) Bid Trader::getNextBid() { char type = RAND_RANGE('A','B'); return getNextBid(type); } Bid Trader::getNextBid(char type) { for(int i = 0; i < NUMSELLER+NUMBUYER; i++) { // int trdId = RAND_RANGE(1,9); if (s<10){trdId=0;type='A';} else {trdId=1;type='B';} s++; int qty = RAND_RANGE(MINQUANTITY, MAXQUANTITY); int price = RAND_RANGE(MINPRICE, MAXPRICE); Bid bid = {nextBidId++, trdId, qty, price, type}; return bid; } } //void Trader::loadRange(BidList &list, int size) { // for (int i=0; i<size; i++) { list.push_back(getNextBid()); } //} // //void Trader::loadRange(BidList &list, char type, int size) { // for (int i=0; i<size; i++) { list.push_back(getNextBid(type)); } //} //---------------------------AUCTIONEER------------------------------------------- class Auctioneer { vector<Auctioneer> List; Trader trader; vector<Bid> list; public: Auctioneer(){}; void accept_bids(const BidList& bid); }; typedef vector<Auctioneer*> bidlist; void Auctioneer::accept_bids(const BidList& bid){ BidList list; //copy (BidList.begin(),BidList.end(),list); } //all the happy display commands void show(const Bid &bid) { cout << "\tBid\t(" << setw(3) << bid.bidId << "\t " << setw(3) << bid.trdId << "\t " << setw(3) << bid.type <<"\t " << setw(3) << bid.qty <<"\t " << setw(3) << bid.price <<")\t\n " ; } void show(const BidList &list) { cout << "\t\tBidID | TradID | Type | Qty | Price \n\n"; for(BidList::const_iterator itr=list.begin(); itr != list.end(); ++itr) { //cout <<"\t\t"; show(*itr); cout << endl; } cout << endl; } //search now checks for failure void show(const char *msg, const BidList &list) { cout << msg << endl; show(list); } void searchTest(BidList &list, int bidId) { cout << "Searching for Bid " << bidId << endl; BidList::const_iterator itr = find(list.begin(), list.end(), bidId); if (itr==list.end()) { cout << "Bid not found."; } else { cout << "Bid has been found. Its : "; show(*itr); } cout << endl; } //comparator function for price: returns true when x belongs before y bool compareBidList(Bid one, Bid two) { if (one.type == 'A' && two.type == 'B') return (one.price < two.price); return false; } void sort(BidList &bidlist) { sort(bidlist.begin(), bidlist.end(), compareBidList); } int main(int argc, char **argv) { Trader trader; BidList bidlist; Auctioneer auctioneer; //bidlist list; auctioneer.accept_bids(bidlist); //trader.loadRange(bidlist, NUMBIDS); show("Bids before sort:", bidlist); sort(bidlist); show("Bids after sort:", bidlist); system("pause"); return 0; }

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  • Class member functions instantiated by traits [policies, actually]

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate member functions? [Update: I used the wrong term here. It should be "policies" rather than "traits." Traits describe existing classes. Policies prescribe synthetic classes.] The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice? UPDATE: Here's another try at explaining it. I want the user to be able to fill out an order (manifest) for a custom optimizer, something like ordering off of a Chinese menu - one from column A, one from column B, etc.. Waiter, from column A (updaters), I'll have the BFGS update with Cholesky-decompositon sauce. From column B (line-searchers), I'll have the cubic interpolation line-search with an eta of 0.4 and a rho of 1e-4, please. Etc... UPDATE: Okay, okay. Here's the playing-around that I've done. I offer it reluctantly, because I suspect it's a completely wrong-headed approach. It runs okay under vc++ 2008. #include <boost/utility.hpp> #include <boost/type_traits/integral_constant.hpp> namespace dj { struct CBFGS { void bar() {printf("CBFGS::bar %d\n", data);} CBFGS(): data(1234){} int data; }; template<class T> struct is_CBFGS: boost::false_type{}; template<> struct is_CBFGS<CBFGS>: boost::true_type{}; struct LMQN {LMQN(): data(54.321){} void bar() {printf("LMQN::bar %lf\n", data);} double data; }; template<class T> struct is_LMQN: boost::false_type{}; template<> struct is_LMQN<LMQN> : boost::true_type{}; // "Order form" struct default_optimizer_traits { typedef CBFGS update_type; // Selection from column A - updaters }; template<class traits> class Optimizer; template<class traits> void foo(typename boost::enable_if<is_LMQN<typename traits::update_type>, Optimizer<traits> >::type& self) { printf(" LMQN %lf\n", self.data); } template<class traits> void foo(typename boost::enable_if<is_CBFGS<typename traits::update_type>, Optimizer<traits> >::type& self) { printf("CBFGS %d\n", self.data); } template<class traits = default_optimizer_traits> class Optimizer{ friend typename traits::update_type; //friend void dj::foo<traits>(typename Optimizer<traits> & self); // How? public: //void foo(void); // How??? void foo() { dj::foo<traits>(*this); } void bar() { data.bar(); } //protected: // How? typedef typename traits::update_type update_type; update_type data; }; } // namespace dj int main() { dj::Optimizer<> opt; opt.foo(); opt.bar(); std::getchar(); return 0; }

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  • Different behavior of functors (copies, assignments) in VS2010 (compared with VS2005)

    - by Patrick
    When moving from VS2005 to VS2010 we noticed a performance decrease, which seemed to be caused by additional copies of a functor. The following code illustrates the problem. It is essential to have a map where the value itself is a set. On both the map and the set we defined a comparison functor (which is templated in the example). #include <iostream> #include <map> #include <set> class A { public: A(int i, char c) : m_i(i), m_c(c) { std::cout << "Construct object " << m_c << m_i << std::endl; } A(const A &a) : m_i(a.m_i), m_c(a.m_c) { std::cout << "Copy object " << m_c << m_i << std::endl; } ~A() { std::cout << "Destruct object " << m_c << m_i << std::endl; } void operator= (const A &a) { m_i = a.m_i; m_c = a.m_c; std::cout << "Assign object " << m_c << m_i << std::endl; } int m_i; char m_c; }; class B : public A { public: B(int i) : A(i, 'B') { } static const char s_c = 'B'; }; class C : public A { public: C(int i) : A(i, 'C') { } static const char s_c = 'C'; }; template <class X> class compareA { public: compareA() : m_i(999) { std::cout << "Construct functor " << X::s_c << m_i << std::endl; } compareA(const compareA &a) : m_i(a.m_i) { std::cout << "Copy functor " << X::s_c << m_i << std::endl; } ~compareA() { std::cout << "Destruct functor " << X::s_c << m_i << std::endl; } void operator= (const compareA &a) { m_i = a.m_i; std::cout << "Assign functor " << X::s_c << m_i << std::endl; } bool operator() (const X &x1, const X &x2) const { std::cout << "Comparing object " << x1.m_i << " with " << x2.m_i << std::endl; return x1.m_i < x2.m_i; } private: int m_i; }; typedef std::set<C, compareA<C> > SetTest; typedef std::map<B, SetTest, compareA<B> > MapTest; int main() { int i = 0; std::cout << "--- " << i++ << std::endl; MapTest mapTest; std::cout << "--- " << i++ << std::endl; SetTest &setTest = mapTest[0]; std::cout << "--- " << i++ << std::endl; } If I compile this code with VS2005 I get the following output: --- 0 Construct functor B999 Copy functor B999 Copy functor B999 Destruct functor B999 Destruct functor B999 --- 1 Construct object B0 Construct functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Destruct functor C999 Destruct object B0 Destruct functor C999 Destruct object B0 --- 2 If I compile this with VS2010, I get the following output: --- 0 Construct functor B999 Copy functor B999 Copy functor B999 Destruct functor B999 Destruct functor B999 --- 1 Construct object B0 Construct functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy functor C999 Assign functor C999 Assign functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy functor C999 Assign functor C999 Assign functor C999 Destruct functor C999 Destruct functor C999 Destruct object B0 Destruct functor C999 Destruct object B0 --- 2 The output for the first statement (constructing the map) is identical. The output for the second statement (creating the first element in the map and getting a reference to it), is much bigger in the VS2010 case: Copy constructor of functor: 10 times vs 8 times Assignment of functor: 2 times vs. 0 times Destructor of functor: 10 times vs 8 times My questions are: Why does the STL copy a functor? Isn't it enough to construct it once for every instantiation of the set? Why is the functor constructed more in the VS2010 case than in the VS2005 case? (didn't check VS2008) And why is it assigned two times in VS2010 and not in VS2005? Are there any tricks to avoid the copy of functors? I saw a similar question at http://stackoverflow.com/questions/2216041/prevent-unnecessary-copies-of-c-functor-objects but I'm not sure that's the same question. Thanks in advance, Patrick

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  • Processing incorrect mac addresses from 802.11 frames with pcap

    - by Quentin Swain
    I'm working throurgh a project with pcap and wireless. Following an example posted in response to oe of my earlier questions I am trying to extract the mac addresses from wireless frames. I have created structures for the radiotap header and a basic management frame. For some reason when it comes to trying to output the mac addresses I am printing out the wrong data. When I compare to wireshark I don't see why the radio tap data is printing out correctly but the mac addresses are not. I don't see any additional padding in the hex dump that wireshark displays when i look at the packets and compare the packets that I have captured. I am somewhat famialar with c but not an expert so maybe I am not using the pointers and structures properly could someone help show me what I am doing wrong? Thanks, Quentin // main.c // MacSniffer // #include <pcap.h> #include <string.h> #include <stdlib.h> #define MAXBYTES2CAPTURE 65535 #ifdef WORDS_BIGENDIAN typedef struct frame_control { unsigned int subtype:4; /*frame subtype field*/ unsigned int protoVer:2; /*frame type field*/ unsigned int version:2; /*protocol version*/ unsigned int order:1; unsigned int protected:1; unsigned int moreDate:1; unsigned int power_management:1; unsigned int retry:1; unsigned int moreFrag:1; unsigned int fromDS:1; unsigned int toDS:1; }frame_control; struct ieee80211_radiotap_header{ u_int8_t it_version; u_int8_t it_pad; u_int16_t it_len; u_int32_t it_present; u_int64_t MAC_timestamp; u_int8_t flags; u_int8_t dataRate; u_int16_t channelfrequency; u_int16_t channFreq_pad; u_int16_t channelType; u_int16_t channType_pad; u_int8_t ssiSignal; u_int8_t ssiNoise; u_int8_t antenna; }; #else typedef struct frame_control { unsigned int protoVer:2; /* protocol version*/ unsigned int type:2; /*frame type field (Management,Control,Data)*/ unsigned int subtype:4; /* frame subtype*/ unsigned int toDS:1; /* frame coming from Distribution system */ unsigned int fromDS:1; /*frame coming from Distribution system */ unsigned int moreFrag:1; /* More fragments?*/ unsigned int retry:1; /*was this frame retransmitted*/ unsigned int powMgt:1; /*Power Management*/ unsigned int moreDate:1; /*More Date*/ unsigned int protectedData:1; /*Protected Data*/ unsigned int order:1; /*Order*/ }frame_control; struct ieee80211_radiotap_header{ u_int8_t it_version; u_int8_t it_pad; u_int16_t it_len; u_int32_t it_present; u_int64_t MAC_timestamp; u_int8_t flags; u_int8_t dataRate; u_int16_t channelfrequency; u_int16_t channelType; int ssiSignal:8; int ssiNoise:8; }; #endif struct wi_frame { u_int16_t fc; u_int16_t wi_duration; u_int8_t wi_add1[6]; u_int8_t wi_add2[6]; u_int8_t wi_add3[6]; u_int16_t wi_sequenceControl; // u_int8_t wi_add4[6]; //unsigned int qosControl:2; //unsigned int frameBody[23124]; }; void processPacket(u_char *arg, const struct pcap_pkthdr* pkthdr, const u_char* packet) { int i= 0, *counter = (int *) arg; struct ieee80211_radiotap_header *rh =(struct ieee80211_radiotap_header *)packet; struct wi_frame *fr= (struct wi_frame *)(packet + rh->it_len); u_char *ptr; //printf("Frame Type: %d",fr->wi_fC->type); printf("Packet count: %d\n", ++(*counter)); printf("Received Packet Size: %d\n", pkthdr->len); if(rh->it_version != NULL) { printf("Radiotap Version: %d\n",rh->it_version); } if(rh->it_pad!=NULL) { printf("Radiotap Pad: %d\n",rh->it_pad); } if(rh->it_len != NULL) { printf("Radiotap Length: %d\n",rh->it_len); } if(rh->it_present != NULL) { printf("Radiotap Present: %c\n",rh->it_present); } if(rh->MAC_timestamp != NULL) { printf("Radiotap Timestamp: %u\n",rh->MAC_timestamp); } if(rh->dataRate != NULL) { printf("Radiotap Data Rate: %u\n",rh->dataRate); } if(rh->channelfrequency != NULL) { printf("Radiotap Channel Freq: %u\n",rh->channelfrequency); } if(rh->channelType != NULL) { printf("Radiotap Channel Type: %06x\n",rh->channelType); } if(rh->ssiSignal != NULL) { printf("Radiotap SSI signal: %d\n",rh->ssiSignal); } if(rh->ssiNoise != NULL) { printf("Radiotap SSI Noise: %d\n",rh->ssiNoise); } ptr = fr->wi_add1; int k= 6; printf("Destination Address:"); do{ printf("%s%X",(k==6)?" ":":",*ptr++); } while(--k>0); printf("\n"); ptr = fr->wi_add2; k=0; printf("Source Address:"); do{ printf("%s%X",(k==6)?" ":":",*ptr++); }while(--k>0); printf("\n"); ptr = fr->wi_add3; k=0; do{ printf("%s%X",(k==6)?" ":":",*ptr++); } while(--k>0); printf("\n"); /* for(int j = 0; j < 23124;j++) { if(fr->frameBody[j]!= NULL) { printf("%x",fr->frameBody[j]); } } */ for (i = 0;i<pkthdr->len;i++) { if(isprint(packet[i +rh->it_len])) { printf("%c",packet[i + rh->it_len]); } else{printf(".");} //print newline after each section of the packet if((i%16 ==0 && i!=0) ||(i==pkthdr->len-1)) { printf("\n"); } } return; } int main(int argc, char** argv) { int count = 0; pcap_t* descr = NULL; char errbuf[PCAP_ERRBUF_SIZE], *device = NULL; struct bpf_program fp; char filter[]="wlan broadcast"; const u_char* packet; memset(errbuf,0,PCAP_ERRBUF_SIZE); device = argv[1]; if(device == NULL) { fprintf(stdout,"Supply a device name "); } descr = pcap_create(device,errbuf); pcap_set_rfmon(descr,1); pcap_set_promisc(descr,1); pcap_set_snaplen(descr,30); pcap_set_timeout(descr,10000); pcap_activate(descr); int dl =pcap_datalink(descr); printf("The Data Link type is %s",pcap_datalink_val_to_name(dl)); //pcap_dispatch(descr,MAXBYTES2CAPTURE,1,512,errbuf); //Open device in promiscuous mode //descr = pcap_open_live(device,MAXBYTES2CAPTURE,1,512,errbuf); /* if(pcap_compile(descr,&fp,filter,0,PCAP_NETMASK_UNKNOWN)==-1) { fprintf(stderr,"Error compiling filter\n"); exit(1); } if(pcap_setfilter(descr,&fp)==-1) { fprintf(stderr,"Error setting filter\n"); exit(1); } */ pcap_loop(descr,0, processPacket, (u_char *) &count); return 0; }

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  • Why does C qicksort function implementation works much slower (tape comparations, tape swapping) than bobble sort function?

    - by Artur Mustafin
    I'm going to implement a toy tape "mainframe" for a students, showing the quickness of "quicksort" class functions (recursive or not, does not really matters, due to the slow hardware, and well known stack reversal techniques) comparatively to the "bubblesort" function class, so, while I'm clear about the hardware implementation ans controllers, i guessed that quicksort function is much faster that other ones in terms of sequence, order and comparation distance (it is much faster to rewind the tape from the middle than from the very end, because of different speed of rewind). Unfortunately, this is not the true, this simple "bubble" code shows great improvements comparatively to the "quicksort" functions in terms of comparison distances, direction and number of comparisons and writes. So I have 3 questions: Does I have mistaken in my implememtation of quicksort function? Does I have mistaken in my implememtation of bubblesoft function? If not, why the "bubblesort" function is works much faster in (comparison and write operations) than "quicksort" function? I already have a "quicksort" function: void quicksort(float *a, long l, long r, const compare_function& compare) { long i=l, j=r, temp, m=(l+r)/2; if (l == r) return; if (l == r-1) { if (compare(a, l, r)) { swap(a, l, r); } return; } if (l < r-1) { while (1) { i = l; j = r; while (i < m && !compare(a, i, m)) i++; while (m < j && !compare(a, m, j)) j--; if (i >= j) { break; } swap(a, i, j); } if (l < m) quicksort(a, l, m, compare); if (m < r) quicksort(a, m, r, compare); return; } } and the kind of my own implememtation of the "bubblesort" function: void bubblesort(float *a, long l, long r, const compare_function& compare) { long i, j, k; if (l == r) { return; } if (l == r-1) { if (compare(a, l, r)) { swap(a, l, r); } return; } if (l < r-1) { while(l < r) { i = l; j = l; while (i < r) { i++; if (!compare(a, j, i)) { continue; } j = i; } if (l < j) { swap(a, l, j); } l++; i = r; k = r; while(l < i) { i--; if (!compare(a, i, k)) { continue; } k = i; } if (k < r) { swap(a, k, r); } r--; } return; } } I have used this sort functions in a test sample code, like this: #include <stdio.h> #include <stdlib.h> #include <math.h> #include <conio.h> long swap_count; long compare_count; typedef long (*compare_function)(float *, long, long ); typedef void (*sort_function)(float *, long , long , const compare_function& ); void init(float *, long ); void print(float *, long ); void sort(float *, long, const sort_function& ); void swap(float *a, long l, long r); long less(float *a, long l, long r); long greater(float *a, long l, long r); void bubblesort(float *, long , long , const compare_function& ); void quicksort(float *, long , long , const compare_function& ); void main() { int n; printf("n="); scanf("%d",&n); printf("\r\n"); long i; float *a = (float *)malloc(n*n*sizeof(float)); sort(a, n, &bubblesort); print(a, n); sort(a, n, &quicksort); print(a, n); free(a); } long less(float *a, long l, long r) { compare_count++; return *(a+l) < *(a+r) ? 1 : 0; } long greater(float *a, long l, long r) { compare_count++; return *(a+l) > *(a+r) ? 1 : 0; } void swap(float *a, long l, long r) { swap_count++; float temp; temp = *(a+l); *(a+l) = *(a+r); *(a+r) = temp; } float tg(float x) { return tan(x); } float ctg(float x) { return 1.0/tan(x); } void init(float *m,long n) { long i,j; for (i = 0; i < n; i++) { for (j=0; j< n; j++) { m[i + j*n] = tg(0.2*(i+1)) + ctg(0.3*(j+1)); } } } void print(float *m, long n) { long i, j; for(i = 0; i < n; i++) { for(j = 0; j < n; j++) { printf(" %5.1f", m[i + j*n]); } printf("\r\n"); } printf("\r\n"); } void sort(float *a, long n, const sort_function& sort) { long i, sort_compare = 0, sort_swap = 0; init(a,n); for(i = 0; i < n*n; i+=n) { if (fmod (i / n, 2) == 0) { compare_count = 0; swap_count = 0; sort(a, i, i+n-1, &less); if (swap_count == 0) { compare_count = 0; sort(a, i, i+n-1, &greater); } sort_compare += compare_count; sort_swap += swap_count; } } printf("compare=%ld\r\n", sort_compare); printf("swap=%ld\r\n", sort_swap); printf("\r\n"); }

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  • InputDispatcher Error

    - by StarDust
    INFO/ActivityManager(68): Process com.example (pid 390) has died. ERROR/InputDispatcher(68): channel '406ed580 com.example/com.example.afeTest (server)' ~ Consumer closed input channel or an error occurred. events=0x8 ERROR/InputDispatcher(68): channel '406ed580 com.example/com.example.afeTest (server)' ~ Channel is unrecoverably broken and will be disposed! ERROR/InputDispatcher(68): Received spurious receive callback for unknown input channel. fd=165, events=0x8 Can anyone tell what may be the reason behind this error? I've ported a native code on the Android-ndk. One thing I noticed regarding fd (that may be some reason :S) My code uses fd_sets which was defined in winsock2.h But I didn't find fd_sets defined in android-ndk. So I had included "select.h" where fd_set is a typedef in the android-ndk: typedef __kernel_fd_set fd_set; Here is the log cat: 04-06 11:15:32.405: INFO/DEBUG(31): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** 04-06 11:15:32.405: INFO/DEBUG(31): Build fingerprint: 'generic/sdk/generic:2.3.3/GRI34/101070:eng/test-keys' 04-06 11:15:32.415: INFO/DEBUG(31): pid: 335, tid: 348 >>> com.example <<< 04-06 11:15:32.426: INFO/DEBUG(31): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr deadbaad 04-06 11:15:32.426: INFO/DEBUG(31): r0 deadbaad r1 0000000c r2 00000027 r3 00000000 04-06 11:15:32.445: INFO/DEBUG(31): r4 00000080 r5 afd46668 r6 0000a000 r7 00000078 04-06 11:15:32.445: INFO/DEBUG(31): r8 804ab00d r9 002a9778 10 00100000 fp 00000001 04-06 11:15:32.445: INFO/DEBUG(31): ip ffffffff sp 44295d10 lr afd19375 pc afd15ef0 cpsr 00000030 04-06 11:15:32.756: INFO/DEBUG(31): #00 pc 00015ef0 /system/lib/libc.so 04-06 11:15:32.756: INFO/DEBUG(31): #01 pc 00013852 /system/lib/libc.so 04-06 11:15:32.767: INFO/DEBUG(31): code around pc: 04-06 11:15:32.785: INFO/DEBUG(31): afd15ed0 68241c23 d1fb2c00 68dae027 d0042a00 04-06 11:15:32.785: INFO/DEBUG(31): afd15ee0 20014d18 6028447d 48174790 24802227 04-06 11:15:32.785: INFO/DEBUG(31): afd15ef0 f7f57002 2106eb56 ec92f7f6 0563aa01 04-06 11:15:32.796: INFO/DEBUG(31): afd15f00 60932100 91016051 1c112006 e818f7f6 04-06 11:15:32.807: INFO/DEBUG(31): afd15f10 2200a905 f7f62002 f7f5e824 2106eb42 04-06 11:15:32.815: INFO/DEBUG(31): code around lr: 04-06 11:15:32.815: INFO/DEBUG(31): afd19354 b0834a0d 589c447b 26009001 686768a5 04-06 11:15:32.825: INFO/DEBUG(31): afd19364 220ce008 2b005eab 1c28d003 47889901 04-06 11:15:32.836: INFO/DEBUG(31): afd19374 35544306 d5f43f01 2c006824 b003d1ee 04-06 11:15:32.836: INFO/DEBUG(31): afd19384 bdf01c30 000281a8 ffffff88 1c0fb5f0 04-06 11:15:32.846: INFO/DEBUG(31): afd19394 43551c3d a904b087 1c16ac01 604d9004 04-06 11:15:32.856: INFO/DEBUG(31): stack: 04-06 11:15:32.856: INFO/DEBUG(31): 44295cd0 00000408 04-06 11:15:32.867: INFO/DEBUG(31): 44295cd4 afd18407 /system/lib/libc.so 04-06 11:15:32.875: INFO/DEBUG(31): 44295cd8 afd4270c /system/lib/libc.so 04-06 11:15:32.875: INFO/DEBUG(31): 44295cdc afd426b8 /system/lib/libc.so 04-06 11:15:32.885: INFO/DEBUG(31): 44295ce0 00000000 04-06 11:15:32.896: INFO/DEBUG(31): 44295ce4 afd19375 /system/lib/libc.so 04-06 11:15:32.896: INFO/DEBUG(31): 44295ce8 804ab00d /data/data/com.example/lib/libAFE.so 04-06 11:15:32.896: INFO/DEBUG(31): 44295cec afd183d9 /system/lib/libc.so 04-06 11:15:32.906: INFO/DEBUG(31): 44295cf0 00000078 04-06 11:15:32.906: INFO/DEBUG(31): 44295cf4 00000000 04-06 11:15:32.906: INFO/DEBUG(31): 44295cf8 afd46668 04-06 11:15:32.906: INFO/DEBUG(31): 44295cfc 0000a000 [heap] 04-06 11:15:32.916: INFO/DEBUG(31): 44295d00 00000078 04-06 11:15:32.927: INFO/DEBUG(31): 44295d04 afd18677 /system/lib/libc.so 04-06 11:15:32.927: INFO/DEBUG(31): 44295d08 df002777 04-06 11:15:32.945: INFO/DEBUG(31): 44295d0c e3a070ad 04-06 11:15:32.945: INFO/DEBUG(31): #00 44295d10 002c43a0 [heap] 04-06 11:15:32.945: INFO/DEBUG(31): 44295d14 002a9900 [heap] 04-06 11:15:32.956: INFO/DEBUG(31): 44295d18 afd46608 04-06 11:15:32.966: INFO/DEBUG(31): 44295d1c afd11010 /system/lib/libc.so 04-06 11:15:32.976: INFO/DEBUG(31): 44295d20 002c4298 [heap] 04-06 11:15:32.976: INFO/DEBUG(31): 44295d24 fffffbdf 04-06 11:15:33.006: INFO/DEBUG(31): 44295d28 000000da 04-06 11:15:33.006: INFO/DEBUG(31): 44295d2c afd46450 04-06 11:15:33.006: INFO/DEBUG(31): 44295d30 000001b4 04-06 11:15:33.026: INFO/DEBUG(31): 44295d34 afd13857 /system/lib/libc.so 04-06 11:15:33.026: INFO/DEBUG(31): #01 44295d38 afd46450 04-06 11:15:33.035: INFO/DEBUG(31): 44295d3c afd13857 /system/lib/libc.so 04-06 11:15:33.056: INFO/DEBUG(31): 44295d40 804ab00d /data/data/com.example/lib/libAFE.so 04-06 11:15:33.056: INFO/DEBUG(31): 44295d44 44295e8c 04-06 11:15:33.056: INFO/DEBUG(31): 44295d48 804ab00d /data/data/com.example/lib/libAFE.so 04-06 11:15:33.056: INFO/DEBUG(31): 44295d4c 804bfec3 /data/data/com.example/lib/libAFE.so 04-06 11:15:33.056: INFO/DEBUG(31): 44295d50 002c43a0 [heap] 04-06 11:15:33.066: INFO/DEBUG(31): 44295d54 44295e8c 04-06 11:15:33.066: INFO/DEBUG(31): 44295d58 804ab00d /data/data/com.example/lib/libAFE.so 04-06 11:15:33.076: INFO/DEBUG(31): 44295d5c 002a9778 [heap] 04-06 11:15:33.085: INFO/DEBUG(31): 44295d60 00000078 04-06 11:15:33.085: INFO/DEBUG(31): 44295d64 afd14769 /system/lib/libc.so 04-06 11:15:33.085: INFO/DEBUG(31): 44295d68 44295e8c 04-06 11:15:33.085: INFO/DEBUG(31): 44295d6c 805d9763 /data/data/com.example/lib/libAFE.so 04-06 11:15:33.085: INFO/DEBUG(31): 44295d70 44295e8c 04-06 11:15:33.085: INFO/DEBUG(31): 44295d74 8051dc35 /data/data/com.example/lib/libAFE.so 04-06 11:15:33.085: INFO/DEBUG(31): 44295d78 0000003a 04-06 11:15:33.085: INFO/DEBUG(31): 44295d7c 002a9900 [heap] 04-06 11:15:37.126: DEBUG/Zygote(33): Process 335 terminated by signal (11) 04-06 11:15:37.146: INFO/ActivityManager(68): Process com.example (pid 335) has died. 04-06 11:15:37.178: ERROR/InputDispatcher(68): channel '406f03a0 com.example/com.example.afeTest (server)' ~ Consumer closed input channel or an error occurred. events=0x8 04-06 11:15:37.178: ERROR/InputDispatcher(68): channel '406f03a0 com.example/com.example.afeTest (server)' ~ Channel is unrecoverably broken and will be disposed! 04-06 11:15:37.185: INFO/BootReceiver(68): Copying /data/tombstones/tombstone_09 to DropBox (SYSTEM_TOMBSTONE) 04-06 11:15:37.576: DEBUG/dalvikvm(68): GC_FOR_MALLOC freed 266K, 47% free 4404K/8199K, external 3520K/3903K, paused 306ms 04-06 11:15:37.835: DEBUG/dalvikvm(68): GC_FOR_MALLOC freed 203K, 47% free 4457K/8391K, external 3520K/3903K, paused 120ms 04-06 11:15:37.886: INFO/WindowManager(68): WIN DEATH: Window{406f03a0 com.example/com.example.afeTest paused=false} 04-06 11:15:38.095: DEBUG/dalvikvm(68): GC_FOR_MALLOC freed 67K, 47% free 4518K/8391K, external 3511K/3903K, paused 94ms 04-06 11:15:38.095: INFO/dalvikvm-heap(68): Grow heap (frag case) to 10.575MB for 196628-byte allocation 04-06 11:15:38.126: DEBUG/dalvikvm(126): GC_EXPLICIT freed 110K, 51% free 2903K/5895K, external 4701K/5293K, paused 2443ms 04-06 11:15:38.217: DEBUG/dalvikvm(68): GC_FOR_MALLOC freed 1K, 46% free 4708K/8647K, external 3511K/3903K, paused 96ms 04-06 11:15:38.225: INFO/WindowManager(68): WIN DEATH: Window{406f72f8 com.example/com.example.afeTest paused=false} 04-06 11:15:38.405: DEBUG/dalvikvm(68): GC_FOR_MALLOC freed 492K, 50% free 4345K/8647K, external 3511K/3903K, paused 96ms 04-06 11:15:38.485: ERROR/InputDispatcher(68): Received spurious receive callback for unknown input channel. fd=164, events=0x8

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  • Trouble passing a template function as an argument to another function in C++

    - by Darel
    Source of the problem -Accelerated C++, problem 8-5 I've written a small program that examines lines of string input, and tallies the number of times a word appears on a given line. The following code accomplishes this: #include <map> #include <iostream> #include <string> #include <vector> #include <list> #include <cctype> #include <iterator> using std::vector; using std::string; using std::cin; using std::cout; using std::endl; using std::getline; using std::istream; using std::string; using std::list; using std::map; using std::isspace; using std::ostream_iterator; using std::allocator; inline void keep_window_open() { cin.clear(); cout << "Please enter EOF to exit\n"; char ch; cin >> ch; return; } template <class Out> void split(const string& s, Out os) { vector<string> ret; typedef string::size_type string_size; string_size i = 0; // invariant: we have processed characters `['original value of `i', `i)' while (i != s.size()) { // ignore leading blanks // invariant: characters in range `['original `i', current `i)' are all spaces while (i != s.size() && isspace(s[i])) ++i; // find end of next word string_size j = i; // invariant: none of the characters in range `['original `j', current `j)' is a space while (j != s.size() && !isspace(s[j])) ++j; // if we found some nonwhitespace characters if (i != j) { // copy from `s' starting at `i' and taking `j' `\-' `i' chars *os++ = (s.substr(i, j - i)); i = j; } } } // find all the lines that refer to each word in the input map<string, vector<int> > xref(istream& in) // works // now try to pass the template function as an argument to function - what do i put for templated type? //map<string, vector<int> > xref(istream& in, void find_words(vector<string, typedef Out) = split) #LINE 1# { string line; int line_number = 0; map<string, vector<int> > ret; // read the next line while (getline(in, line)) { ++line_number; // break the input line into words vector<string> words; // works // #LINE 2# split(line, back_inserter(words)); // #LINE 3# //find_words(line, back_inserter(words)); // #LINE 4# attempting to use find_words as an argument to function // remember that each word occurs on the current line for (vector<string>::const_iterator it = words.begin(); it != words.end(); ++it) ret[*it].push_back(line_number); } return ret; } int main() { cout << endl << "Enter lines of text, followed by EOF (^Z):" << endl; // call `xref' using `split' by default map<string, vector<int> > ret = xref(cin); // write the results for (map<string, vector<int> >::const_iterator it = ret.begin(); it != ret.end(); ++it) { // write the word cout << it->first << " occurs on line(s): "; // followed by one or more line numbers vector<int>::const_iterator line_it = it->second.begin(); cout << *line_it; // write the first line number ++line_it; // write the rest of the line numbers, if any while (line_it != it->second.end()) { cout << ", " << *line_it; ++line_it; } // write a new line to separate each word from the next cout << endl; } keep_window_open(); return 0; } As you can see, the split function is a template function to handle various types of output iterators as desired. My problem comes when I try to generalize the xref function by passing in the templated split function as an argument. I can't seem to get the type correct. So my question is, can you pass a template function to another function as an argument, and if so, do you have to declare all types before passing it? Or can the compiler infer the types from the way the templated function is used in the body? To demonstrate the errors I get, comment out the existing xref function header, and uncomment the alternate header I'm trying to get working (just below the following commment line.) Also comment the lines tagged LINE 2 and LINE 3 and uncomment LINE 4, which is attempting to use the argument find_words (which defaults to split.) Thanks for any feedback!

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  • Little more help with writing a o buffer with libjpeg

    - by Richard Knop
    So I have managed to find another question discussing how to use the libjpeg to compress an image to jpeg. I have found this code which is supposed to work: Compressing IplImage to JPEG using libjpeg in OpenCV Here's the code (it compiles ok): /* This a custom destination manager for jpeglib that enables the use of memory to memory compression. See IJG documentation for details. */ typedef struct { struct jpeg_destination_mgr pub; /* base class */ JOCTET* buffer; /* buffer start address */ int bufsize; /* size of buffer */ size_t datasize; /* final size of compressed data */ int* outsize; /* user pointer to datasize */ int errcount; /* counts up write errors due to buffer overruns */ } memory_destination_mgr; typedef memory_destination_mgr* mem_dest_ptr; /* ------------------------------------------------------------- */ /* MEMORY DESTINATION INTERFACE METHODS */ /* ------------------------------------------------------------- */ /* This function is called by the library before any data gets written */ METHODDEF(void) init_destination (j_compress_ptr cinfo) { mem_dest_ptr dest = (mem_dest_ptr)cinfo->dest; dest->pub.next_output_byte = dest->buffer; /* set destination buffer */ dest->pub.free_in_buffer = dest->bufsize; /* input buffer size */ dest->datasize = 0; /* reset output size */ dest->errcount = 0; /* reset error count */ } /* This function is called by the library if the buffer fills up I just reset destination pointer and buffer size here. Note that this behavior, while preventing seg faults will lead to invalid output streams as data is over- written. */ METHODDEF(boolean) empty_output_buffer (j_compress_ptr cinfo) { mem_dest_ptr dest = (mem_dest_ptr)cinfo->dest; dest->pub.next_output_byte = dest->buffer; dest->pub.free_in_buffer = dest->bufsize; ++dest->errcount; /* need to increase error count */ return TRUE; } /* Usually the library wants to flush output here. I will calculate output buffer size here. Note that results become incorrect, once empty_output_buffer was called. This situation is notified by errcount. */ METHODDEF(void) term_destination (j_compress_ptr cinfo) { mem_dest_ptr dest = (mem_dest_ptr)cinfo->dest; dest->datasize = dest->bufsize - dest->pub.free_in_buffer; if (dest->outsize) *dest->outsize += (int)dest->datasize; } /* Override the default destination manager initialization provided by jpeglib. Since we want to use memory-to-memory compression, we need to use our own destination manager. */ GLOBAL(void) jpeg_memory_dest (j_compress_ptr cinfo, JOCTET* buffer, int bufsize, int* outsize) { mem_dest_ptr dest; /* first call for this instance - need to setup */ if (cinfo->dest == 0) { cinfo->dest = (struct jpeg_destination_mgr *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, sizeof (memory_destination_mgr)); } dest = (mem_dest_ptr) cinfo->dest; dest->bufsize = bufsize; dest->buffer = buffer; dest->outsize = outsize; /* set method callbacks */ dest->pub.init_destination = init_destination; dest->pub.empty_output_buffer = empty_output_buffer; dest->pub.term_destination = term_destination; } /* ------------------------------------------------------------- */ /* MEMORY SOURCE INTERFACE METHODS */ /* ------------------------------------------------------------- */ /* Called before data is read */ METHODDEF(void) init_source (j_decompress_ptr dinfo) { /* nothing to do here, really. I mean. I'm not lazy or something, but... we're actually through here. */ } /* Called if the decoder wants some bytes that we cannot provide... */ METHODDEF(boolean) fill_input_buffer (j_decompress_ptr dinfo) { /* we can't do anything about this. This might happen if the provided buffer is either invalid with regards to its content or just a to small bufsize has been given. */ /* fail. */ return FALSE; } /* From IJG docs: "it's not clear that being smart is worth much trouble" So I save myself some trouble by ignoring this bit. */ METHODDEF(void) skip_input_data (j_decompress_ptr dinfo, INT32 num_bytes) { /* There might be more data to skip than available in buffer. This clearly is an error, so screw this mess. */ if ((size_t)num_bytes > dinfo->src->bytes_in_buffer) { dinfo->src->next_input_byte = 0; /* no buffer byte */ dinfo->src->bytes_in_buffer = 0; /* no input left */ } else { dinfo->src->next_input_byte += num_bytes; dinfo->src->bytes_in_buffer -= num_bytes; } } /* Finished with decompression */ METHODDEF(void) term_source (j_decompress_ptr dinfo) { /* Again. Absolute laziness. Nothing to do here. Boring. */ } GLOBAL(void) jpeg_memory_src (j_decompress_ptr dinfo, unsigned char* buffer, size_t size) { struct jpeg_source_mgr* src; /* first call for this instance - need to setup */ if (dinfo->src == 0) { dinfo->src = (struct jpeg_source_mgr *) (*dinfo->mem->alloc_small) ((j_common_ptr) dinfo, JPOOL_PERMANENT, sizeof (struct jpeg_source_mgr)); } src = dinfo->src; src->next_input_byte = buffer; src->bytes_in_buffer = size; src->init_source = init_source; src->fill_input_buffer = fill_input_buffer; src->skip_input_data = skip_input_data; src->term_source = term_source; /* IJG recommend to use their function - as I don't know **** about how to do better, I follow this recommendation */ src->resync_to_restart = jpeg_resync_to_restart; } All I need to do is replace the jpeg_stdio_dest in my program with this code: int numBytes = 0; //size of jpeg after compression char * storage = new char[150000]; //storage buffer JOCTET *jpgbuff = (JOCTET*)storage; //JOCTET pointer to buffer jpeg_memory_dest(&cinfo,jpgbuff,150000,&numBytes); So I need some help to incorporate the above four lines into this function which now works but writes to a file instead of a memory: int write_jpeg_file( char *filename ) { struct jpeg_compress_struct cinfo; struct jpeg_error_mgr jerr; /* this is a pointer to one row of image data */ JSAMPROW row_pointer[1]; FILE *outfile = fopen( filename, "wb" ); if ( !outfile ) { printf("Error opening output jpeg file %s\n!", filename ); return -1; } cinfo.err = jpeg_std_error( &jerr ); jpeg_create_compress(&cinfo); jpeg_stdio_dest(&cinfo, outfile); /* Setting the parameters of the output file here */ cinfo.image_width = width; cinfo.image_height = height; cinfo.input_components = bytes_per_pixel; cinfo.in_color_space = color_space; /* default compression parameters, we shouldn't be worried about these */ jpeg_set_defaults( &cinfo ); /* Now do the compression .. */ jpeg_start_compress( &cinfo, TRUE ); /* like reading a file, this time write one row at a time */ while( cinfo.next_scanline < cinfo.image_height ) { row_pointer[0] = &raw_image[ cinfo.next_scanline * cinfo.image_width * cinfo.input_components]; jpeg_write_scanlines( &cinfo, row_pointer, 1 ); } /* similar to read file, clean up after we're done compressing */ jpeg_finish_compress( &cinfo ); jpeg_destroy_compress( &cinfo ); fclose( outfile ); /* success code is 1! */ return 1; } Anybody could help me out a bit with it? I've tried meddling with it but I am not sure how to do it. I I just replace this line: jpeg_stdio_dest(&cinfo, outfile); It's not going to work. There is more stuff that needs to be changed a bit in that function and I am being a little lost from all those pointers and memory management.

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