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• Sending a message to nil?

  - by Ryan Delucchi

  As a Java developer who is reading Apple's Objective-C 2.0 documentation: I wonder as to what sending a message to nil means - let alone how it is actually useful. Taking an excerpt from the documentation: There are several patterns in Cocoa that take advantage of this fact. The value returned from a message to nil may also be valid: If the method returns an object, any pointer type, any integer scalar of size less than or equal to sizeof(void*), a float, a double, a long double, or a long long, then a message sent to nil returns 0. If the method returns a struct, as defined by the Mac OS X ABI Function Call Guide to be returned in registers, then a message sent to nil returns 0.0 for every field in the data structure. Other struct data types will not be filled with zeros. If the method returns anything other than the aforementioned value types the return value of a message sent to nil is undefined. Has Java rendered my brain incapable of grokking the explanation above? Or is there something that I am missing that would make this as clear as glass? Note: Yes, I do get the idea of messages/receivers in Objective-C, I am simply confused about a receiver that happens to be nil.

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• Checking if a function has C-linkage at compile-time [unsolvable]

  - by scjohnno

  Is there any way to check if a given function is declared with C-linkage (that is, with extern "C") at compile-time? I am developing a plugin system. Each plugin can supply factory functions to the plugin-loading code. However, this has to be done via name (and subsequent use of GetProcAddress or dlsym). This requires that the functions be declared with C-linkage so as to prevent name-mangling. It would be nice to be able to throw a compiler error if the referred-to function is declared with C++-linkage (as opposed to finding out at runtime when a function with that name does not exist). Here's a simplified example of what I mean: extern "C" void my_func() { } void my_other_func() { } // Replace this struct with one that actually works template<typename T> struct is_c_linkage { static const bool value = true; }; template<typename T> void assertCLinkage(T *func) { static_assert(is_c_linkage<T>::value, "Supplied function does not have C-linkage"); } int main() { assertCLinkage(my_func); // Should compile assertCLinkage(my_other_func); // Should NOT compile } Is there a possible implementation of is_c_linkage that would throw a compiler error for the second function, but not the first? I'm not sure that it's possible (though it may exist as a compiler extension, which I'd still like to know of). Thanks.

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• Remove duplicates in a linked list before adding - C

  - by DesperateCoders

  Hi, My question is about removing duplicates from a linked list. But i want to do it before adding to linked list. struct myStr{int number; mystr *next;} void append(mystr **q,int item) { myStr *temp; temp = *q; myStr *newone; if(*q==NULL)// There should be control of previous elements. Call of keysearch function. { temp = (myStr *)malloc(sizeof(myStr)); temp->number =size; temp->next=NULL; *q=temp; } else //And also here { temp = *q; while(temp->next !=NULL) { temp=temp->next; } newone = (myStr *)malloc(sizeof(myStr)); newone->count = size; newone->next=NULL; temp->next=newone; } } int keysearch (myStr *p) { struct myStr *temp = p; int found = 0; int key= p->number; while (temp->number != NULL) { if(temp->number == key) { found = 1; } temp = temp->next; } return found; } My problem is in keySearch. I don't know what is wrong? Or is there another way for doing this.

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• linked list printing using while loop and combining like terms

  - by C Z

  i have a problem printing out my linked list. My program asks the user to enter many different coefficients and degrees and makes it a polynomial and using mergesort it sorts it and then prints it, now i want to combine like terms and i have a problem doing so. thats part of my function that i don't know what is wrong with it: Term* p; p=poly; if (p==0) cout<<"---empty list---"; while(p !=0) if (p->coef==(p->next)->coef){ cout<<(p->deg)+((p->next)->deg)<<"x^"<<(p->coef)<<endl; p=p->next;} if (p->coef !=(p->next)->coef){ cout<<p->deg<<"x"<<p->coef<<"+"; p=p->next;} cout<<endl; } and thats my struct: struct Term { int deg; float coef; Term *next; }; typedef Term* Poly;

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• Getting template metaprogramming compile-time constants at runtime

  - by GMan - Save the Unicorns

  Background Consider the following: template <unsigned N> struct Fibonacci { enum { value = Fibonacci<N-1>::value + Fibonacci<N-2>::value }; }; template <> struct Fibonacci<1> { enum { value = 1 }; }; template <> struct Fibonacci<0> { enum { value = 0 }; }; This is a common example and we can get the value of a Fibonacci number as a compile-time constant: int main(void) { std::cout << "Fibonacci(15) = "; std::cout << Fibonacci<15>::value; std::cout << std::endl; } But you obviously cannot get the value at runtime: int main(void) { std::srand(static_cast<unsigned>(std::time(0))); // ensure the table exists up to a certain size // (even though the rest of the code won't work) static const unsigned fibbMax = 20; Fibonacci<fibbMax>::value; // get index into sequence unsigned fibb = std::rand() % fibbMax; std::cout << "Fibonacci(" << fibb << ") = "; std::cout << Fibonacci<fibb>::value; std::cout << std::endl; } Because fibb is not a compile-time constant. Question So my question is: What is the best way to peek into this table at run-time? The most obvious solution (and "solution" should be taken lightly), is to have a large switch statement: unsigned fibonacci(unsigned index) { switch (index) { case 0: return Fibonacci<0>::value; case 1: return Fibonacci<1>::value; case 2: return Fibonacci<2>::value; . . . case 20: return Fibonacci<20>::value; default: return fibonacci(index - 1) + fibonacci(index - 2); } } int main(void) { std::srand(static_cast<unsigned>(std::time(0))); static const unsigned fibbMax = 20; // get index into sequence unsigned fibb = std::rand() % fibbMax; std::cout << "Fibonacci(" << fibb << ") = "; std::cout << fibonacci(fibb); std::cout << std::endl; } But now the size of the table is very hard coded and it wouldn't be easy to expand it to say, 40. The only one I came up with that has a similiar method of query is this: template <int TableSize = 40> class FibonacciTable { public: enum { max = TableSize }; static unsigned get(unsigned index) { if (index == TableSize) { return Fibonacci<TableSize>::value; } else { // too far, pass downwards return FibonacciTable<TableSize - 1>::get(index); } } }; template <> class FibonacciTable<0> { public: enum { max = 0 }; static unsigned get(unsigned) { // doesn't matter, no where else to go. // must be 0, or the original value was // not in table return 0; } }; int main(void) { std::srand(static_cast<unsigned>(std::time(0))); // get index into sequence unsigned fibb = std::rand() % FibonacciTable<>::max; std::cout << "Fibonacci(" << fibb << ") = "; std::cout << FibonacciTable<>::get(fibb); std::cout << std::endl; } Which seems to work great. The only two problems I see are: Potentially large call stack, since calculating Fibonacci<2 requires we go through TableMax all the way to 2, and: If the value is outside of the table, it returns zero as opposed to calculating it. So is there something I am missing? It seems there should be a better way to pick out these values at runtime. A template metaprogramming version of a switch statement perhaps, that generates a switch statement up to a certain number? Thanks in advance.

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• Ethernet Communication Error

  - by SivaKumar

  Hi, I wrote a program to query the status of the Ethernet printer for that i created a TCP Stream Socket and i send the query command to the printer.In case of Error less condition it returns No error status but in error case its getting hang at recv command.Even i used Non blocking now the recv command returns nothing and error set as Resource temporarily unavailable. code: #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <errno.h> #include <stdlib.h> #include <fcntl.h> #include <sys/ioctl.h> #include <sys/socket.h> #include <signal.h> #include <termios.h> #include <poll.h> #include <netinet/tcp.h> #include <stdarg.h> int main() { int ConnectSocket,ConnectSocket1,select_err,err,nRet,nBytesRead; struct timeval waitTime = {10,30}; fd_set socket_set; unsigned char * dataBuf = NULL; unsigned char tempVar, tempVar1, tempVar2, tempVar3; char reset[] = "\033E 2\r"; char print[] = "\033A 1\r"; char buf[1024]={0}; ConnectSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); printf("The Socket ID is %d\n",ConnectSocket); if (ConnectSocket < 0) { perror("socket()"); return 0; } struct sockaddr_in clientService; clientService.sin_family = AF_INET; clientService.sin_addr.s_addr = inet_addr("192.168.0.129"); //Printer IP clientService.sin_port = htons( 9100); // Printer Port if ( connect( ConnectSocket, (struct sockaddr*) &clientService, sizeof(clientService) ) == -1) { perror("connect()"); close(ConnectSocket); return -1; } /* if((nRet = ioctl(ConnectSocket , FIONREAD, &nBytesRead) == -1)) { perror("ioctl()"); } perror("ioctl()"); */ FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); do { errno=0; select_err = select(ConnectSocket+1, NULL, &socket_set, NULL, &waitTime); }while(errno==EINPROGRESS); if (-1 == select_err || 0 == select_err) { int optVal = 0; int optLen = sizeof(optVal); if(select_err == -1) { perror("select() write-side"); } else { //Timeout errno=0; err = getsockopt(ConnectSocket, SOL_SOCKET, SO_ERROR, (char*)&optVal, &optLen); printf("the return of the getsockopt is %d\n",err); printf("the opt val is %s\n",(char*)optVal); perror("getsockopt()"); if(err == -1) { perror("getsockopt() write-side"); } } printf("Select Failed during write - ConnectSocket: %d\n", ConnectSocket); //close(ConnectSocket); return -1; } err = send(ConnectSocket,print,sizeof(print)-1, 0); printf("\n No of Bytes Send is %d\n",err); if(err == -1 || err ==0) { perror("send()"); //close(ConnectSocket); return -1; } FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); do { errno=0; select_err = select(ConnectSocket+1, NULL, &socket_set, NULL, &waitTime); }while(errno==EINPROGRESS); if (-1 == select_err || 0 == select_err) { printf("Select Failed during write - ConnectSocket: %d\n", ConnectSocket); return -1; } err = send(ConnectSocket,reset,sizeof(reset)-1, 0); printf("\n No of Bytes Send is %d\n",err); if(err == -1 || err ==0) { perror("send()"); //close(ConnectSocket); return -1; } FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); printf("i am in reading \n"); select_err = select(ConnectSocket+1, &socket_set, NULL, NULL, &waitTime); printf("the retun of the read side select is %d \n",select_err); perror("select()"); if (-1 == select_err|| 0 == select_err) { printf("Read timeout; ConnectSocket: %d\n", ConnectSocket); close(ConnectSocket); perror("close()"); return -1; } printf("Before Recv\n"); nBytesRead = recv(ConnectSocket , buf, 1024, 0); printf("No of Bytes read is %d\n",nBytesRead); printf("%s\n",buf); if(nBytesRead == -1) { perror("recv()"); close(ConnectSocket); perror("clode()"); return -1; } close(ConnectSocket); return 1; }

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• Is it reasonable that a random disk seek & read costs ~16ms?

  - by fzhang

  I am frustrated about the latency of random reading from a non-ssd disk. Based on results from following test program, it speeds ~16 ms for a random read of just 512 bytes without help of os cache. I tried changing 512 to larger values, such as 25k, and the latency did not increase as much. I guess it is because the disk seek dominates the time. I understand that random reading is inherently slow, but just want to be sure that ~16ms is reasonable, even for non-ssd disk. #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> #include <sys/unistd.h> #include <fcntl.h> #include <limits.h> #include <stdio.h> #include <string.h> int main(int argc, char** argv) { int fd = open(argv[1], O_RDONLY); if (fd < 0) { fprintf(stderr, "Failed open %s\n", argv[1]); return -1; } const size_t count = 512; const off_t offset = 25990611 / 2; char buffer[count] = { '\0' }; struct timeval start_time; gettimeofday(&start_time, NULL); off_t ret = lseek(fd, offset, SEEK_SET); if (ret != offset) { perror("lseek error"); close(fd); return -1; } ret = read(fd, buffer, count); if (ret != count) { fprintf(stderr, "Failed reading all: %ld\n", ret); close(fd); return -1; } struct timeval end_time; gettimeofday(&end_time, NULL); printf("tv_sec: %ld, tv_usec: %ld\n", end_time.tv_sec - start_time.tv_sec, end_time.tv_usec - start_time.tv_usec); close(fd); return 0; }

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• Strange things appear on running the program

  - by FILIaS

  Hey! I'm fixing a program but I'm facing a problem and I cant really realize what's the wrong on the code. I would appreciate any help. I didnt post all the code...but i think with this part you can get an idea of it. With the following function enter() I wanna add user commands' datas to a list. eg. user give the command: "enter james bond 007 gun" 'james' is supposed to be the name, 'bond' the surname, 007 the amount and the rest is the description. I use strtok in order to 'cut' the command,then i put each name on a temp array. Then i call InsertSort in order to put the datas on a linked list but in alphabetical order depending on the surname that users give. I wanna keep the list on order and put each time the elements on the right position. /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void)//user command: enter <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char command[1500]; while (command[j]!=' ' && command[j]!='\0') { temp[k]=command[j]; j++; k++; } temp[k]='\0'; char *curToken = strtok(temp," "); printf("temp is:%s \n",temp); char short_name[50],surname[50],description[1000]; signed int amount; //short_name=(char *)malloc(sizeof (char *)); //surname=(char *)malloc(sizeof (char *)); //description=(char *)malloc(sizeof (char *)); //amount=(int *)malloc(sizeof (int *)); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken !='\0'; ++n) { if (curToken) { strncpy(short_name, curToken, sizeof (char *)); / } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) strncpy(surname, curToken, sizeof (char *)); / printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { strncpy(description, curToken, sizeof (char *)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname) != NULL) printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); InsertSort(&head,short_name, surname, amount, description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } /********Uses special case code for the head end********/ void SortedInsert(catalog** headRef, catalogPointer newNode,char short_name[],char surname[],signed int amount,char description[]) { strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); // Special case for the head end if (*headRef == NULL||(*headRef)->surname >= newNode->surname) { newNode->next = *headRef; *headRef = newNode; } else { // Locate the node before the point of insertion catalogPointer current = *headRef; catalogPointer temp=current->next; while ( temp!=NULL ) { if(strcmp(temp->surname,newNode->surname)<0 ) current = temp; } newNode->next = temp; temp = newNode; } } // Given a list, change it to be in sorted order (using SortedInsert()). void InsertSort(catalog** headRef,char short_name[],char surname[],signed int amount,char description[]) { catalogPointer result = NULL; // build the answer here catalogPointer current = *headRef; // iterate over the original list catalogPointer next; while (current!=NULL) { next = current->next; // tricky - note the next pointer before we change it SortedInsert(&result,current,short_name,surname,amount,description); current = next; } *headRef = result; } Running the program I get these strange things (garbage?)... Choose your selection: enter james bond 007 gun Your command is: enter james bond 007 gun temp is:james What you entered for saving: Short Name: james SurName: Amount: 0 Description: 0T?? Try to entry james 0 0T?? in the catalog list! Entry done! Also I'm facing a problem on how to use the 'malloc' on this program. Thanks in advance. . .

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• GCC ICE -- alternative function syntax, variadic templates and tuples

  - by Marc H.

  (Related to C++0x, How do I expand a tuple into variadic template function arguments?.) The following code (see below) is taken from this discussion. The objective is to apply a function to a tuple. I simplified the template parameters and modified the code to allow for a return value of generic type. While the original code compiles fine, when I try to compile the modified code with GCC 4.4.3, g++ -std=c++0x main.cc -o main GCC reports an internal compiler error (ICE) with the following message: main.cc: In function ‘int main()’: main.cc:53: internal compiler error: in tsubst_copy, at cp/pt.c:10077 Please submit a full bug report, with preprocessed source if appropriate. See <file:///usr/share/doc/gcc-4.4/README.Bugs> for instructions. Question: Is the code correct? or is the ICE triggered by illegal code? // file: main.cc #include <tuple> // Recursive case template<unsigned int N> struct Apply_aux { template<typename F, typename T, typename... X> static auto apply(F f, const T& t, X... x) -> decltype(Apply_aux<N-1>::apply(f, t, std::get<N-1>(t), x...)) { return Apply_aux<N-1>::apply(f, t, std::get<N-1>(t), x...); } }; // Terminal case template<> struct Apply_aux<0> { template<typename F, typename T, typename... X> static auto apply(F f, const T&, X... x) -> decltype(f(x...)) { return f(x...); } }; // Actual apply function template<typename F, typename T> auto apply(F f, const T& t) -> decltype(Apply_aux<std::tuple_size<T>::value>::apply(f, t)) { return Apply_aux<std::tuple_size<T>::value>::apply(f, t); } // Testing #include <string> #include <iostream> int f(int p1, double p2, std::string p3) { std::cout << "int=" << p1 << ", double=" << p2 << ", string=" << p3 << std::endl; return 1; } int g(int p1, std::string p2) { std::cout << "int=" << p1 << ", string=" << p2 << std::endl; return 2; } int main() { std::tuple<int, double, char const*> tup(1, 2.0, "xxx"); std::cout << apply(f, tup) << std::endl; std::cout << apply(g, std::make_tuple(4, "yyy")) << std::endl; } Remark: If I hardcode the return type in the recursive case (see code), then everything is fine. That is, substituting this snippet for the recursive case does not trigger the ICE: // Recursive case (hardcoded return type) template<unsigned int N> struct Apply_aux { template<typename F, typename T, typename... X> static int apply(F f, const T& t, X... x) { return Apply_aux<N-1>::apply(f, t, std::get<N-1>(t), x...); } }; Alas, this is an incomplete solution to the original problem.

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• Using a boost::fusion::map in boost::spirit::karma

  - by user1097105

  I am using boost spirit to parse some text files into a data structure and now I am beginning to generate text from this data structure (using spirit karma). One attempt at a data structure is a boost::fusion::map (as suggested in an answer to this question). But although I can use boost::spirit::qi::parse() and get data in it easily, when I tried to generate text from it using karma, I failed. Below is my attempt (look especially at the "map_data" type). After some reading and playing around with other fusion types, I found boost::fusion::vector and BOOST_FUSION_DEFINE_ASSOC_STRUCT. I succeeded to generate output with both of them, but they don't seem ideal: in vector you cannot access a member using a name (it is like a tuple) -- and in the other solution, I don't think I need both ways (member name and key type) to access the members. #include <iostream> #include <string> #include <boost/spirit/include/karma.hpp> #include <boost/fusion/include/map.hpp> #include <boost/fusion/include/make_map.hpp> #include <boost/fusion/include/vector.hpp> #include <boost/fusion/include/as_vector.hpp> #include <boost/fusion/include/transform.hpp> struct sb_key; struct id_key; using boost::fusion::pair; typedef boost::fusion::map < pair<sb_key, int> , pair<id_key, unsigned long> > map_data; typedef boost::fusion::vector < int, unsigned long > vector_data; #include <boost/fusion/include/define_assoc_struct.hpp> BOOST_FUSION_DEFINE_ASSOC_STRUCT( (), assocstruct_data, (int, a, sb_key) (unsigned long, b, id_key)) namespace karma = boost::spirit::karma; template <typename X> std::string to_string ( const X& data ) { std::string generated; std::back_insert_iterator<std::string> sink(generated); karma::generate_delimited ( sink, karma::int_ << karma::ulong_, karma::space, data ); return generated; } int main() { map_data d1(boost::fusion::make_map<sb_key, id_key>(234, 35314988526ul)); vector_data d2(boost::fusion::make_vector(234, 35314988526ul)); assocstruct_data d3(234,35314988526ul); std::cout << "map_data as_vector: " << boost::fusion::as_vector(d1) << std::endl; //std::cout << "map_data to_string: " << to_string(d1) << std::endl; //*FAIL No 1* std::cout << "at_key (sb_key): " << boost::fusion::at_key<sb_key>(d1) << boost::fusion::at_c<0>(d1) << std::endl << std::endl; std::cout << "vector_data: " << d2 << std::endl; std::cout << "vector_data to_string: " << to_string(d2) << std::endl << std::endl; std::cout << "assoc_struct as_vector: " << boost::fusion::as_vector(d3) << std::endl; std::cout << "assoc_struct to_string: " << to_string(d3) << std::endl; std::cout << "at_key (sb_key): " << boost::fusion::at_key<sb_key>(d3) << d3.a << boost::fusion::at_c<0>(d3) << std::endl; return 0; } Including the commented line gives lots of pages of compilation errors, among which notably something like: no known conversion for argument 1 from ‘boost::fusion::pair’ to ‘double’ no known conversion for argument 1 from ‘boost::fusion::pair’ to ‘float’ Might it be that to_string needs the values of the map_data, and not the pairs? Though I am not good with templates, I tried to get a vector from a map using transform in the following way template <typename P> struct take_second { typename P::second_type operator() (P p) { return p.second; } }; // ... inside main() pair <char, int> ff(32); std::cout << "take_second (expect 32): " << take_second<pair<char,int>>()(ff) << std::endl; std::cout << "transform map_data and to_string: " << to_string(boost::fusion::transform(d1, take_second<>())); //*FAIL No 2* But I don't know what types am I supposed to give when instantiating take_second and anyway I think there must be an easier way to get (iterate over) the values of a map (is there?) If you answer this question, please also give your opinion on whether using an ASSOC_STRUCT or a map is better.

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• C -Segmentation fault !

  - by FILIaS

  It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else //SEGMENTATION APPEARS WHEN IT GETS HERE! { tmp=second->next; newNode->next=tmp; first->next=newNode; } } UPDATE: SegFault appears only when it gets on the 'else' loop of InsertSort() function. I observed that segmentation fault appears when i try to put on the list names that are after it. For example, if in the list exists: [Name:b Surname:b Amount:6 Description:b] [Name:c Surname:c Amount:5 Description:c] [Name:d Surname:d Amount:4 Description:d] [Name:e Surname:e Amount:3 Description:e] [Name:g Surname:g Amount:2 Description:g] [Name:x Surname:x Amount:1 Description:x] and i put: " x z 77 gege" there is a segmentation but if i put "x a 77 gege" it continues normally....

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• varnish: Alter response body

  - by soulmerge

  I need to rewrite the response received by the backend in varnish. The C-function is ready, embedded in the configuration file, and passes tests run on response headers. But I need to access the body of the response. I couldn't find a way to extract that from the response struct, though. Does anyone have an idea how I could extract it anyway?

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• C -Segmentation fault after the 4th call of the function!

  - by FILIaS

  It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); //SEGMENTATION ON THE 4TH RUN OF PROGRAM STOPS HERE depending on the names each time it gets! while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else { tmp=second->next; newNode->next=tmp; first->next=newNode; } }

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• How to programatically read native DLL imports in C#?

  - by Eric

  The large hunk of C# code below is intended to print the imports of a native DLL. I copied it from from this link and modified it very slightly, just to use LoadLibraryEx as Mike Woodring does here. I find that when I call the Foo.Test method with the original example's target, MSCOREE.DLL, it prints all the imports fine. But when I use other dlls like GDI32.DLL or WSOCK32.DLL the imports do not get printed. What's missing from this code that would let it print all the imports as, for example, DUMPBIN.EXE does? (Is there a hint I'm not grokking in the original comment that says, "using mscoree.dll as an example as it doesnt export any thing"?) Here's the extract that just shows how it's being invoked: public static void Test() { // WORKS: var path = @"c:\windows\system32\mscoree.dll"; // NO ERRORS, BUT NO IMPORTS PRINTED EITHER: //var path = @"c:\windows\system32\gdi32.dll"; //var path = @"c:\windows\system32\wsock32.dll"; var hLib = LoadLibraryEx(path, 0, DONT_RESOLVE_DLL_REFERENCES | LOAD_IGNORE_CODE_AUTHZ_LEVEL); TestImports(hLib, true); } And here is the whole code example: namespace PETest2 { [StructLayout(LayoutKind.Explicit)] public unsafe struct IMAGE_IMPORT_BY_NAME { [FieldOffset(0)] public ushort Hint; [FieldOffset(2)] public fixed char Name[1]; } [StructLayout(LayoutKind.Explicit)] public struct IMAGE_IMPORT_DESCRIPTOR { #region union /// <summary> /// CSharp doesnt really support unions, but they can be emulated by a field offset 0 /// </summary> [FieldOffset(0)] public uint Characteristics; // 0 for terminating null import descriptor [FieldOffset(0)] public uint OriginalFirstThunk; // RVA to original unbound IAT (PIMAGE_THUNK_DATA) #endregion [FieldOffset(4)] public uint TimeDateStamp; [FieldOffset(8)] public uint ForwarderChain; [FieldOffset(12)] public uint Name; [FieldOffset(16)] public uint FirstThunk; } [StructLayout(LayoutKind.Explicit)] public struct THUNK_DATA { [FieldOffset(0)] public uint ForwarderString; // PBYTE [FieldOffset(4)] public uint Function; // PDWORD [FieldOffset(8)] public uint Ordinal; [FieldOffset(12)] public uint AddressOfData; // PIMAGE_IMPORT_BY_NAME } public unsafe class Interop { #region Public Constants public static readonly ushort IMAGE_DIRECTORY_ENTRY_IMPORT = 1; #endregion #region Private Constants #region CallingConvention CALLING_CONVENTION /// <summary> /// Specifies the calling convention. /// </summary> /// <remarks> /// Specifies <see cref="CallingConvention.Winapi" /> for Windows to /// indicate that the default should be used. /// </remarks> private const CallingConvention CALLING_CONVENTION = CallingConvention.Winapi; #endregion CallingConvention CALLING_CONVENTION #region IMPORT DLL FUNCTIONS private const string KERNEL_DLL = "kernel32"; private const string DBGHELP_DLL = "Dbghelp"; #endregion #endregion Private Constants [DllImport(KERNEL_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "GetModuleHandleA"), SuppressUnmanagedCodeSecurity] public static extern void* GetModuleHandleA(/*IN*/ char* lpModuleName); [DllImport(KERNEL_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "GetModuleHandleW"), SuppressUnmanagedCodeSecurity] public static extern void* GetModuleHandleW(/*IN*/ char* lpModuleName); [DllImport(KERNEL_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "IsBadReadPtr"), SuppressUnmanagedCodeSecurity] public static extern bool IsBadReadPtr(void* lpBase, uint ucb); [DllImport(DBGHELP_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "ImageDirectoryEntryToData"), SuppressUnmanagedCodeSecurity] public static extern void* ImageDirectoryEntryToData(void* Base, bool MappedAsImage, ushort DirectoryEntry, out uint Size); } static class Foo { // From winbase.h in the Win32 platform SDK. // const uint DONT_RESOLVE_DLL_REFERENCES = 0x00000001; const uint LOAD_IGNORE_CODE_AUTHZ_LEVEL = 0x00000010; [DllImport("kernel32.dll"), SuppressUnmanagedCodeSecurity] static extern uint LoadLibraryEx(string fileName, uint notUsedMustBeZero, uint flags); public static void Test() { //var path = @"c:\windows\system32\mscoree.dll"; //var path = @"c:\windows\system32\gdi32.dll"; var path = @"c:\windows\system32\wsock32.dll"; var hLib = LoadLibraryEx(path, 0, DONT_RESOLVE_DLL_REFERENCES | LOAD_IGNORE_CODE_AUTHZ_LEVEL); TestImports(hLib, true); } // using mscoree.dll as an example as it doesnt export any thing // so nothing shows up if you use your own module. // and the only none delayload in mscoree.dll is the Kernel32.dll private static void TestImports( uint hLib, bool mappedAsImage ) { unsafe { //fixed (char* pszModule = "mscoree.dll") { //void* hMod = Interop.GetModuleHandleW(pszModule); void* hMod = (void*)hLib; uint size = 0; uint BaseAddress = (uint)hMod; if (hMod != null) { Console.WriteLine("Got handle"); IMAGE_IMPORT_DESCRIPTOR* pIID = (IMAGE_IMPORT_DESCRIPTOR*)Interop.ImageDirectoryEntryToData((void*)hMod, mappedAsImage, Interop.IMAGE_DIRECTORY_ENTRY_IMPORT, out size); if (pIID != null) { Console.WriteLine("Got Image Import Descriptor"); while (!Interop.IsBadReadPtr((void*)pIID->OriginalFirstThunk, (uint)size)) { try { char* szName = (char*)(BaseAddress + pIID->Name); string name = Marshal.PtrToStringAnsi((IntPtr)szName); Console.WriteLine("pIID->Name = {0} BaseAddress - {1}", name, (uint)BaseAddress); THUNK_DATA* pThunkOrg = (THUNK_DATA*)(BaseAddress + pIID->OriginalFirstThunk); while (!Interop.IsBadReadPtr((void*)pThunkOrg->AddressOfData, 4U)) { char* szImportName; uint Ord; if ((pThunkOrg->Ordinal & 0x80000000) > 0) { Ord = pThunkOrg->Ordinal & 0xffff; Console.WriteLine("imports ({0}).Ordinal{1} - Address: {2}", name, Ord, pThunkOrg->Function); } else { IMAGE_IMPORT_BY_NAME* pIBN = (IMAGE_IMPORT_BY_NAME*)(BaseAddress + pThunkOrg->AddressOfData); if (!Interop.IsBadReadPtr((void*)pIBN, (uint)sizeof(IMAGE_IMPORT_BY_NAME))) { Ord = pIBN->Hint; szImportName = (char*)pIBN->Name; string sImportName = Marshal.PtrToStringAnsi((IntPtr)szImportName); // yes i know i am a lazy ass Console.WriteLine("imports ({0}).{1}@{2} - Address: {3}", name, sImportName, Ord, pThunkOrg->Function); } else { Console.WriteLine("Bad ReadPtr Detected or EOF on Imports"); break; } } pThunkOrg++; } } catch (AccessViolationException e) { Console.WriteLine("An Access violation occured\n" + "this seems to suggest the end of the imports section\n"); Console.WriteLine(e); } pIID++; } } } } } Console.WriteLine("Press Any Key To Continue......"); Console.ReadKey(); } }

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• C programming: hashtable insertion/search

  - by Ricardo Campos

  Hello i have a problem with my hash table its implemented like this: #define HT_SIZE 10 typedef struct _list_t_ { char key[20]; char string[20]; char prevValue[20]; struct _list_t_ *next; } list_t; typedef struct _hash_table_t_ { int size; /* the size of the table */ list_t ***table; /* first */ sem_t lock; } hash_table_t; I have a Linked list with 3 pointers because i want a hash table with several partitions (shards), here is my initialization of my Hash table: hash_table_t *create_hash_table(int NUM_SERVER_THREADS, int num_shards){ hash_table_t *new_table; int j,i; if (HT_SIZE<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the hashtable structure */ new_table = (hash_table_t*)malloc(sizeof(hash_table_t)*HT_SIZE); /* Attempt to allocate memory for the table itself */ new_table->table = (list_t ***)calloc(1,sizeof(list_t **)); /* Initialize the elements of the table */ for(j=0; j<num_shards; j++){ new_table->table[j] = (list_t **)calloc(1,sizeof(list_t *)); for(i=0; i<HT_SIZE; i++){ new_table->table[j][i] = (list_t *)calloc(1,sizeof(list_t )); } } /* Set the table's size */ new_table->size = HT_SIZE; sem_init(&new_table->lock, 0, 1); return new_table; } Here is my search function to search in the hash table list_t *lookup_string(hash_table_t *hashtable, char *key, int shardId){ list_t *list ; int hashval = hash(key); /* Go to the correct list based on the hash value and see if key is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ sem_wait(&hashtable->lock); for(list = hashtable->table[shardId][hashval]; list != NULL; list =list->next) { if (strcmp(key, list->key) == 0){ sem_post(&hashtable->lock); return list; } } sem_post(&hashtable->lock); return NULL; } And my insert function: char *add_string(hash_table_t *hashtable, char *str,char *key, int shardId){ list_t *new_list; list_t *current_list; unsigned int hashval = hash(key); /*printf("|%d|%d|%s|\n",hashval,shardId,key);*/ /* Lock for concurrency */ sem_wait(&hashtable->lock); /* Attempt to allocate memory for list */ new_list = (list_t*)malloc(sizeof(list_t)); /* Does item already exist? */ sem_post(&hashtable->lock); current_list = lookup_string(hashtable, key,shardId); sem_wait(&hashtable->lock); /* item already exists, don't insert it again. */ if (current_list != NULL){ strcpy(new_list->prevValue,current_list->string); strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; sem_post(&hashtable->lock); return new_list->prevValue; } /* Insert into list */ strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; /* Unlock */ sem_post(&hashtable->lock); return new_list->prevValue; } My main class runs some of tests by executing the insertion / reading / delete from the elements of the hash table the problem is when i have more than 4 partitions/shards the tests stop at the first reading element saying it returned the wrong value NULL on the search function, when its less than 4 it runs perfectly well and passes all the tests. You can see my main.c in here if you want to give a look: http://hostcode.sourceforge.net/view/1105 My complete Hash table code: http://hostcode.sourceforge.net/view/1103 And other functions where hash table code is executed: .c file http://hostcode.sourceforge.net/view/1104 .h file http://hostcode.sourceforge.net/view/1106 Thank for you time, i appreciate any help you can give to me this is a college important project that I'm trying to solve and I'm stuck here for 2 days.

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• bandwidth throttling C linux

  - by bob moch

  hi im currently creating a function to create a sleep time i can pause between packets for my port scanner im creating for personal/educational use for my home network. what im currently doing is opening /proc/net/dev and reading the 9th set of digits for the eth0 interface to find out the current packets being set and then reading it again and doing some math to figure out a delay to sleep between sending a packet to a port to identify it and fingerprint it. my problem is that no matter what throttle % i use it always seems to send the same rate of packets. i think its mainly my way of mathematically creating my sleep delay. edit:: dont mind the function declaration and the struct stuff all im doing is spawning this function in a thread and passing a pointer to a struct to the function, recreating the struct locally and then freeing the passed structs memory. void *bandwidthmonitor_cmd(void *param) { char cmdline[1024], *bytedata[19]; int i = 0, ii = 0; long long prevbytes = 0, currentbytes = 0, elapsedbytes = 0, byteusage = 0, maxthrottle = 0; command_struct bandwidth = *((command_struct *)param); free(param); //printf("speed: %d\n throttle: %d\n\n", UPLOAD_SPEED, bandwidth.throttle); maxthrottle = UPLOAD_SPEED * bandwidth.throttle / 100; //printf("max throttle:%lld\n", maxthrottle); FILE *f = fopen("/proc/net/dev", "r"); if(f != NULL) { while(1) { while(fgets(cmdline, sizeof(cmdline), f) != NULL) { cmdline[strlen(cmdline)] = '\0'; if(strncmp(cmdline, " eth0", 6) == 0) { bytedata[0] = strtok(cmdline, " "); while(bytedata[i] != NULL) { i++; bytedata[i] = strtok(NULL, " "); } bytedata[i + 1] = '\0'; currentbytes = atoi(bytedata[9]); } } i = 0; rewind(f); elapsedbytes = currentbytes - prevbytes; prevbytes = currentbytes; byteusage = 8 * (elapsedbytes / 1024); //printf("usage:%lld\n",byteusage); if(ii & 0x40) { SLEEP += (maxthrottle - byteusage) * -1.1;//-2.5; if(SLEEP < 0){ SLEEP = 0; } //printf("sleep:%d\n", SLEEP); } usleep(25000); ii++; } } return NULL; } SLEEP and UPLOAD_SPEED are global variables and UPLOAD_SPEED is in kb/s and generated via a speedtest function that gets the upload speed of my computer. this function is running inside a POSIX thread updating SLEEP which my threads doing the socket work grab to sleep by after every packet. as testing instead of only doing the ports i want to check i make it do all the ports over and over again so i can run dstat on a machine to check bandwidth and no matter what bandwidth.throttle is set to it always seems to generate the same amount of bandwidth to the dstat machine. the way i calculate how much i "should" throttle by is by finding the maximum throttle speed which is defined as maxthrottle = upload_speed * throttle / 100; for example if my upload speed was 1000kb/s and my throttle was 90 (90%) my max throttle would be 900kb/s from there it would find the current bytes sent from /proc/net/dev and then find my sleep time via incrementing or decrementing it via sleep += (maxthrottle - bytesysed) * -1.1; this should in theory increase or decrease the sleep time based on how many bytes used there are. the if(ii & 0x40) statement is just for some moderation control. it makes it so it only sets sleep to a new time every 30-40 iterations. final notes: the main problem is that the sleep timer does not seem to modify the speed of packets being set. or maybe its just my implementation because on a freshly restarted machine where /proc/net/dev has low numbers of bytes sent it seems to raise the sleep timer accordingly on my 60kb/s upload machine (ex if i set the throttle to 2 it will incline the sleep timer until network bandwidth out reaches the max bandwidth threshold, but when i try running it on a server which as been online forever it doesnt seem to work as nicely if at all. if anyone can suggest a new method of monitoring the network to adjust a sleep delay then let me know or if anyone sees a flaw in my code. thank you.

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• 11415 compile errors FTW?!

  - by Koning Baard

  Hello. This is something I've really never seen but, I downloaded the source code of the sine wave example at http://www.audiosynth.com/sinewavedemo.html . It is in an old Project Builder Project format, and I want to compile it with Xcode (GCC). However, Xcode gives me 11415 compile errors. The first few are (all in the precompilation of AppKit.h): /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:31:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:31: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:33:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:33: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:35:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:35: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:36:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:36: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:37:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:37: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:38:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:38: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:40:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:40: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:42:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:42: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:48:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:48: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:54:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:54: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:59:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:59: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:61:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:61: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:69:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:69: error: expected identifier or '(' before '+' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:71:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:71: error: expected identifier or '(' before '+' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:39:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:39: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:40:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:40: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:41:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:41: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:42:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:42: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:43:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:43: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:44:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:44: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:45:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:45: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:46:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:46: error: expected identifier or '(' before '-' token Some of the code is: HAL.c /* * HAL.c * Sinewave * * Created by james on Fri Apr 27 2001. * Copyright (c) 2001 __CompanyName__. All rights reserved. * */ #include "HAL.h" #include "math.h" appGlobals gAppGlobals; OSStatus appIOProc (AudioDeviceID inDevice, const AudioTimeStamp* inNow, const AudioBufferList* inInputData, const AudioTimeStamp* inInputTime, AudioBufferList* outOutputData, const AudioTimeStamp* inOutputTime, void* device); #define FailIf(cond, handler) \ if (cond) { \ goto handler; \ } #define FailWithAction(cond, action, handler) \ if (cond) { \ { action; } \ goto handler; \ } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // HAL Sample Code ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ //#define noErr 0 //#define false 0 OSStatus SetupHAL (appGlobalsPtr globals) { OSStatus err = noErr; UInt32 count, bufferSize; AudioDeviceID device = kAudioDeviceUnknown; AudioStreamBasicDescription format; // get the default output device for the HAL count = sizeof(globals->device); // it is required to pass the size of the data to be returned err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &count, (void *) &device); fprintf(stderr, "kAudioHardwarePropertyDefaultOutputDevice %d\n", err); if (err != noErr) goto Bail; // get the buffersize that the default device uses for IO count = sizeof(globals->deviceBufferSize); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyBufferSize, &count, &bufferSize); fprintf(stderr, "kAudioDevicePropertyBufferSize %d %d\n", err, bufferSize); if (err != noErr) goto Bail; // get a description of the data format used by the default device count = sizeof(globals->deviceFormat); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyStreamFormat, &count, &format); fprintf(stderr, "kAudioDevicePropertyStreamFormat %d\n", err); fprintf(stderr, "sampleRate %g\n", format.mSampleRate); fprintf(stderr, "mFormatFlags %08X\n", format.mFormatFlags); fprintf(stderr, "mBytesPerPacket %d\n", format.mBytesPerPacket); fprintf(stderr, "mFramesPerPacket %d\n", format.mFramesPerPacket); fprintf(stderr, "mChannelsPerFrame %d\n", format.mChannelsPerFrame); fprintf(stderr, "mBytesPerFrame %d\n", format.mBytesPerFrame); fprintf(stderr, "mBitsPerChannel %d\n", format.mBitsPerChannel); if (err != kAudioHardwareNoError) goto Bail; FailWithAction(format.mFormatID != kAudioFormatLinearPCM, err = paramErr, Bail); // bail if the format is not linear pcm // everything is ok so fill in these globals globals->device = device; globals->deviceBufferSize = bufferSize; globals->deviceFormat = format; Bail: return (err); } /* struct AudioStreamBasicDescription { Float64 mSampleRate; // the native sample rate of the audio stream UInt32 mFormatID; // the specific encoding type of audio stream UInt32 mFormatFlags; // flags specific to each format UInt32 mBytesPerPacket; // the number of bytes in a packet UInt32 mFramesPerPacket; // the number of frames in each packet UInt32 mBytesPerFrame; // the number of bytes in a frame UInt32 mChannelsPerFrame; // the number of channels in each frame UInt32 mBitsPerChannel; // the number of bits in each channel }; typedef struct AudioStreamBasicDescription AudioStreamBasicDescription; */ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // This is a simple playThru ioProc. It simply places the data in the input buffer back into the output buffer. // Watch out for feedback from Speakers to Microphone OSStatus appIOProc (AudioDeviceID inDevice, const AudioTimeStamp* inNow, const AudioBufferList* inInputData, const AudioTimeStamp* inInputTime, AudioBufferList* outOutputData, const AudioTimeStamp* inOutputTime, void* appGlobals) { appGlobalsPtr globals = appGlobals; int i; double phase = gAppGlobals.phase; double amp = gAppGlobals.amp; double pan = gAppGlobals.pan; double freq = gAppGlobals.freq * 2. * 3.14159265359 / globals->deviceFormat.mSampleRate; int numSamples = globals->deviceBufferSize / globals->deviceFormat.mBytesPerFrame; // assume floats for now.... float *out = outOutputData->mBuffers[0].mData; for (i=0; i<numSamples; ++i) { float wave = sin(phase) * amp; phase = phase + freq; *out++ = wave * (1.0-pan); *out++ = wave * pan; } gAppGlobals.phase = phase; return (kAudioHardwareNoError); } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ OSStatus StartPlayingThruHAL(appGlobalsPtr globals) { OSStatus err = kAudioHardwareNoError; if (globals->soundPlaying) return 0; globals->phase = 0.0; err = AudioDeviceAddIOProc(globals->device, appIOProc, (void *) globals); // setup our device with an IO proc if (err != kAudioHardwareNoError) goto Bail; err = AudioDeviceStart(globals->device, appIOProc); // start playing sound through the device if (err != kAudioHardwareNoError) goto Bail; globals->soundPlaying = true; // set the playing status global to true Bail: return (err); } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ OSStatus StopPlayingThruHAL(appGlobalsPtr globals) { OSStatus err = kAudioHardwareNoError; if (!globals->soundPlaying) return 0; err = AudioDeviceStop(globals->device, appIOProc); // stop playing sound through the device if (err != kAudioHardwareNoError) goto Bail; err = AudioDeviceRemoveIOProc(globals->device, appIOProc); // remove the IO proc from the device if (err != kAudioHardwareNoError) goto Bail; globals->soundPlaying = false; // set the playing status global to false Bail: return (err); } Sinewave.m // // a very simple Cocoa CoreAudio app // by James McCartney [email protected] www.audiosynth.com // // Sinewave - this class implements a sine oscillator with dezippered control of frequency, pan and amplitude // #import "Sinewave.h" // define a C struct from the Obj-C object so audio callback can access data typedef struct { @defs(Sinewave); } sinewavedef; // this is the audio processing callback. OSStatus appIOProc (AudioDeviceID inDevice, const AudioTimeStamp* inNow, const AudioBufferList* inInputData, const AudioTimeStamp* inInputTime, AudioBufferList* outOutputData, const AudioTimeStamp* inOutputTime, void* defptr) { sinewavedef* def = defptr; // get access to Sinewave's data int i; // load instance vars into registers double phase = def->phase; double amp = def->amp; double pan = def->pan; double freq = def->freq; double ampz = def->ampz; double panz = def->panz; double freqz = def->freqz; int numSamples = def->deviceBufferSize / def->deviceFormat.mBytesPerFrame; // assume floats for now.... float *out = outOutputData->mBuffers[0].mData; for (i=0; i<numSamples; ++i) { float wave = sin(phase) * ampz; // generate sine wave phase = phase + freqz; // increment phase // write output *out++ = wave * (1.0-panz); // left channel *out++ = wave * panz; // right channel // de-zipper controls panz = 0.001 * pan + 0.999 * panz; ampz = 0.001 * amp + 0.999 * ampz; freqz = 0.001 * freq + 0.999 * freqz; } // save registers back to object def->phase = phase; def->freqz = freqz; def->ampz = ampz; def->panz = panz; return kAudioHardwareNoError; } @implementation Sinewave - (void) setup { OSStatus err = kAudioHardwareNoError; UInt32 count; device = kAudioDeviceUnknown; initialized = NO; // get the default output device for the HAL count = sizeof(device); // it is required to pass the size of the data to be returned err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &count, (void *) &device); if (err != kAudioHardwareNoError) { fprintf(stderr, "get kAudioHardwarePropertyDefaultOutputDevice error %ld\n", err); return; } // get the buffersize that the default device uses for IO count = sizeof(deviceBufferSize); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyBufferSize, &count, &deviceBufferSize); if (err != kAudioHardwareNoError) { fprintf(stderr, "get kAudioDevicePropertyBufferSize error %ld\n", err); return; } fprintf(stderr, "deviceBufferSize = %ld\n", deviceBufferSize); // get a description of the data format used by the default device count = sizeof(deviceFormat); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyStreamFormat, &count, &deviceFormat); if (err != kAudioHardwareNoError) { fprintf(stderr, "get kAudioDevicePropertyStreamFormat error %ld\n", err); return; } if (deviceFormat.mFormatID != kAudioFormatLinearPCM) { fprintf(stderr, "mFormatID != kAudioFormatLinearPCM\n"); return; } if (!(deviceFormat.mFormatFlags & kLinearPCMFormatFlagIsFloat)) { fprintf(stderr, "Sorry, currently only works with float format....\n"); return; } initialized = YES; fprintf(stderr, "mSampleRate = %g\n", deviceFormat.mSampleRate); fprintf(stderr, "mFormatFlags = %08lX\n", deviceFormat.mFormatFlags); fprintf(stderr, "mBytesPerPacket = %ld\n", deviceFormat.mBytesPerPacket); fprintf(stderr, "mFramesPerPacket = %ld\n", deviceFormat.mFramesPerPacket); fprintf(stderr, "mChannelsPerFrame = %ld\n", deviceFormat.mChannelsPerFrame); fprintf(stderr, "mBytesPerFrame = %ld\n", deviceFormat.mBytesPerFrame); fprintf(stderr, "mBitsPerChannel = %ld\n", deviceFormat.mBitsPerChannel); } - (void)setAmpVal:(double)val { amp = val; } - (void)setFreqVal:(double)val { freq = val * 2. * 3.14159265359 / deviceFormat.mSampleRate; } - (void)setPanVal:(double)val { pan = val; } - (BOOL)start { OSStatus err = kAudioHardwareNoError; sinewavedef *def; if (!initialized) return false; if (soundPlaying) return false; // initialize phase and de-zipper filters. phase = 0.0; freqz = freq; ampz = amp; panz = pan; def = (sinewavedef *)self; err = AudioDeviceAddIOProc(device, appIOProc, (void *) def); // setup our device with an IO proc if (err != kAudioHardwareNoError) return false; err = AudioDeviceStart(device, appIOProc); // start playing sound through the device if (err != kAudioHardwareNoError) return false; soundPlaying = true; // set the playing status global to true return true; } - (BOOL)stop { OSStatus err = kAudioHardwareNoError; if (!initialized) return false; if (!soundPlaying) return false; err = AudioDeviceStop(device, appIOProc); // stop playing sound through the device if (err != kAudioHardwareNoError) return false; err = AudioDeviceRemoveIOProc(device, appIOProc); // remove the IO proc from the device if (err != kAudioHardwareNoError) return false; soundPlaying = false; // set the playing status global to false return true; } @end Can anyone help me compiling this example? I'd really appriciate it. Thanks

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• Getting time in ubuntu

  - by user2578666

  include #include <stdio.h> int GetTime() { struct timespec tsp; clock_gettime(CLOCK_REALTIME, &tsp); //Call clock_gettime to fill tsp fprintf(stdout, "time=%d.%d\n", tsp.tv_sec, tsp.tv_nsec); fflush(stdout); } I am trying to compile the above code but it keeps throwing the error: time.c: In function ‘GetTime’: time.c:12:4: warning: implicit declaration of function ‘clock_gettime’ [-Wimplicit-function-declaration] time.c:12:18: error: ‘CLOCK_REALTIME’ undeclared (first use in this function) time.c:12:18: note: each undeclared identifier is reported only once for each function it appears in time.c:14:4: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘__time_t’ [-Wformat] time.c:14:4: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘long int’ [-Wformat] I have tried compiling with -lrt flag and -std=gnu99. Nothing works.

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• Installing gtk-config and/or fsv in Ubuntu 10.10

  - by Wayne Werner

  Hi, I'm trying to install the File System Visualizer (think "It's a UNIX System! I know this!" from Jurassic Park) on Ubuntu 10.10. I've got the .tar.gz downloaded, and extracted. However, when I ./configure, I get this output: loading cache ./config.cache checking for a BSD compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking whether make sets ${MAKE}... yes checking for working aclocal... found checking for working autoconf... found checking for working automake... found checking for working autoheader... found checking for working makeinfo... missing checking for gcc... gcc checking whether the C compiler (gcc ) works... yes checking whether the C compiler (gcc ) is a cross-compiler... no checking whether we are using GNU C... yes checking whether gcc accepts -g... yes checking how to run the C preprocessor... gcc -E checking for ranlib... ranlib checking for POSIXized ISC... no checking for dirent.h that defines DIR... yes checking for opendir in -ldir... no checking for ANSI C header files... yes checking whether time.h and sys/time.h may both be included... yes checking for strings.h... yes checking for sys/time.h... yes checking for unistd.h... yes checking for working const... yes checking for mode_t... yes checking for uid_t in sys/types.h... yes checking for pid_t... yes checking for size_t... yes checking for comparison_fn_t... yes checking for st_blocks in struct stat... yes checking whether struct tm is in sys/time.h or time.h... time.h checking for working alloca.h... yes checking for alloca... yes checking for working fnmatch... yes checking for strftime... yes checking for getcwd... yes checking for gettimeofday... yes checking for mktime... yes checking for strcspn... yes checking for strdup... yes checking for strspn... yes checking for strtod... yes checking for strtoul... yes checking for scandir... yes checking for inline... inline checking for off_t... yes checking for unistd.h... (cached) yes checking for getpagesize... yes checking for working mmap... yes checking for argz.h... yes checking for limits.h... yes checking for locale.h... yes checking for nl_types.h... yes checking for malloc.h... yes checking for string.h... yes checking for unistd.h... (cached) yes checking for sys/param.h... yes checking for getcwd... (cached) yes checking for munmap... yes checking for putenv... yes checking for setenv... yes checking for setlocale... yes checking for strchr... yes checking for strcasecmp... yes checking for strdup... (cached) yes checking for __argz_count... yes checking for __argz_stringify... yes checking for __argz_next... yes checking for stpcpy... yes checking for LC_MESSAGES... yes checking whether NLS is requested... yes checking whether included gettext is requested... no checking for libintl.h... yes checking for gettext in libc... yes checking for msgfmt... /usr/bin/msgfmt checking for dcgettext... yes checking for gmsgfmt... /usr/bin/msgfmt checking for xgettext... /usr/bin/xgettext checking for gtk-config... no checking for GTK - version >= 1.2.1... no *** The gtk-config script installed by GTK could not be found *** If GTK was installed in PREFIX, make sure PREFIX/bin is in *** your path, or set the GTK_CONFIG environment variable to the *** full path to gtk-config. configure: error: Cannot find proper GTK+ version Obviously it's looking for gtk-config. However, apparently it doesn't exist in the repos anymore. Then this post mentioned that gtkglarea solved their problem, as mentioned in this file. Of course that poster neatly forgets to mention exactly what and how gtkglarea solved their problem, and Google is mostly devoid of information on the problem. So I come here asking for help! I would like to install fsv, but it tells me gtk-config doesn't exist. How can I fix this problem in Ubuntu 10.10? Thanks!

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• E_FAIL: An undetermined error occurred (-2147467259) when loading a cube texture

  - by Boreal

  I'm trying to implement a skybox into my engine, and I'm having some trouble loading the image as a cube map. Everything works (but it doesn't look right) if I don't load using an ImageLoadInformation struct in the ShaderResourceView.FromFile() method, but it breaks if I do. I need to, of course, because I need to tell SlimDX to load it as a cubemap. How can I fix this? Here is my new loading code after the "fix": public static void LoadCubeTexture(string filename) { ImageLoadInformation loadInfo = new ImageLoadInformation() { BindFlags = BindFlags.ShaderResource, CpuAccessFlags = CpuAccessFlags.None, Depth = 32, FilterFlags = FilterFlags.None, FirstMipLevel = 0, Format = SlimDX.DXGI.Format.B8G8R8A8_UNorm, Height = 512, MipFilterFlags = FilterFlags.Linear, MipLevels = 1, OptionFlags = ResourceOptionFlags.TextureCube, Usage = ResourceUsage.Default, Width = 512 }; textures.Add(filename, ShaderResourceView.FromFile(Graphics.device, "Resources/" + filename, loadInfo)); } Each of the faces of my cube texture are 512x512.

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• Adding VFACE semantic causes overlapping output semantics error

  - by user1423893

  My pixel shader input is a follows struct VertexShaderOut { float4 Position : POSITION0; float2 TextureCoordinates : TEXCOORD0; float4 PositionClone : TEXCOORD1; // Final position values must be cloned to be used in PS calculations float3 Normal : TEXCOORD2; //float3x3 TBN : TEXCOORD3; float CullFace : VFACE; // A negative value faces backwards (-1), while a positive value (+1) faces the camera (requires ps_3_0) }; I'm using ps_3_0 and I wish to utilise the VFACE semantic for correct lighting of normals depending on the cull mode. If I add the VFACE semantic then I get the following errors: error X5639: dcl usage+index: position,0 has already been specified for an output register error X4504: overlapping output semantics Why would this occur? I can't see why there would be too much data.

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• Failed to compile Network Manager 0.9.4

  - by Oleksa

  After upgrading to 12.04 I needed to re-compile Network Manager to the version 0.9.4.0 again. However with the version 9.4.0 I faced with the error during compilation with libdns-manager: $ make ... Making all in dns-manager make[4]: ????? ? ??????? "/home/stasevych/install/network-manager/nm0.9.4.0/network-manager-0.9.4.0/src/dns-manager" /bin/bash ../../libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I. -I../.. -I../../src/logging -I../../libnm-util -I../../libnm-util -I../../src -I../../include -I../../include -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -DLOCALSTATEDIR=\"/usr/local/var\" -Wall -std=gnu89 -g -O2 -Wshadow -Wmissing-declarations -Wmissing-prototypes -Wdeclaration-after-statement -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare -fno-strict-aliasing -Wno-unused-but-set-variable -Wundef -Werror -MT libdns_manager_la-nm-dns-manager.lo -MD -MP -MF .deps/libdns_manager_la-nm-dns-manager.Tpo -c -o libdns_manager_la-nm-dns-manager.lo `test -f 'nm-dns-manager.c' || echo './'`nm-dns-manager.c libtool: compile: gcc -DHAVE_CONFIG_H -I. -I../.. -I../../src/logging -I../../libnm-util -I../../libnm-util -I../../src -I../../include -I../../include -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -DLOCALSTATEDIR=\"/usr/local/var\" -Wall -std=gnu89 -g -O2 -Wshadow -Wmissing-declarations -Wmissing-prototypes -Wdeclaration-after-statement -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare -fno-strict-aliasing -Wno-unused-but-set-variable -Wundef -Werror -MT libdns_manager_la-nm-dns-manager.lo -MD -MP -MF .deps/libdns_manager_la-nm-dns-manager.Tpo -c nm-dns-manager.c -fPIC -DPIC -o .libs/libdns_manager_la-nm-dns-manager.o mv -f .deps/libdns_manager_la-nm-dns-manager.Tpo .deps/libdns_manager_la-nm-dns-manager.Plo /bin/bash ../../libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I. -I../.. -I../../src/logging -I../../libnm-util -I../../libnm-util -I../../src -I../../include -I../../include -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -DLOCALSTATEDIR=\"/usr/local/var\" -Wall -std=gnu89 -g -O2 -Wshadow -Wmissing-declarations -Wmissing-prototypes -Wdeclaration-after-statement -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare -fno-strict-aliasing -Wno-unused-but-set-variable -Wundef -Werror -MT libdns_manager_la-nm-dns-dnsmasq.lo -MD -MP -MF .deps/libdns_manager_la-nm-dns-dnsmasq.Tpo -c -o libdns_manager_la-nm-dns-dnsmasq.lo `test -f 'nm-dns-dnsmasq.c' || echo './'`nm-dns-dnsmasq.c libtool: compile: gcc -DHAVE_CONFIG_H -I. -I../.. -I../../src/logging -I../../libnm-util -I../../libnm-util -I../../src -I../../include -I../../include -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/libnl3 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -DLOCALSTATEDIR=\"/usr/local/var\" -Wall -std=gnu89 -g -O2 -Wshadow -Wmissing-declarations -Wmissing-prototypes -Wdeclaration-after-statement -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare -fno-strict-aliasing -Wno-unused-but-set-variable -Wundef -Werror -MT libdns_manager_la-nm-dns-dnsmasq.lo -MD -MP -MF .deps/libdns_manager_la-nm-dns-dnsmasq.Tpo -c nm-dns-dnsmasq.c -fPIC -DPIC -o .libs/libdns_manager_la-nm-dns-dnsmasq.o nm-dns-dnsmasq.c: In function 'update': nm-dns-dnsmasq.c:274:2: error: passing argument 1 of 'g_slist_copy' discards 'const' qualifier from pointer target type [-Werror] /usr/include/glib-2.0/glib/gslist.h:82:10: note: expected 'struct GSList *' but argument is of type 'const struct GSList *' cc1: all warnings being treated as errors make[4]: *** [libdns_manager_la-nm-dns-dnsmasq.lo] ??????? 1 make[4]: ??????? ??????? "/home/stasevych/install/network-manager/nm0.9.4.0/network-manager-0.9.4.0/src/dns-manager" make[3]: *** [all-recursive] ??????? 1 make[3]: ??????? ??????? "/home/stasevych/install/network-manager/nm0.9.4.0/network-manager-0.9.4.0/src" make[2]: *** [all] ??????? 2 make[2]: ??????? ??????? "/home/stasevych/install/network-manager/nm0.9.4.0/network-manager-0.9.4.0/src" make[1]: *** [all-recursive] ??????? 1 make[1]: ??????? ??????? "/home/stasevych/install/network-manager/nm0.9.4.0/network-manager-0.9.4.0" make: *** [all] ??????? 2 Has anybody faced with the similar errors? Thank you in advance for your help.

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• E_INVALIDARG: An invalid parameter was passed to the returning function (-2147024809) when loading a cube texture

  - by Boreal

  I'm trying to implement a skybox into my engine, and I'm having some trouble loading the image as a cube map. Everything works (but it doesn't look right) if I don't load using an ImageLoadInformation struct in the ShaderResourceView.FromFile() method, but it breaks if I do. I need to, of course, because I need to tell SlimDX to load it as a cubemap. How can I fix this? Here is my new loading code after the "fix": public static void LoadCubeTexture(string filename) { ImageLoadInformation loadInfo = ImageLoadInformation.FromDefaults(); loadInfo.OptionFlags = ResourceOptionFlags.TextureCube; textures.Add(filename, ShaderResourceView.FromFile(Graphics.device, "Resources/" + filename, loadInfo)); }

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