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  • Want to Receive dynamic length data from a message queue in IPC?

    - by user1089679
    Here I have to send and receive dynamic data using a SysV message queue. so in structure filed i have dynamic memory allocation char * because its size may be varies. so how can i receive this type of message at receiver side. Please let me know how can i send dynamic length of data with message queue. I am getting problem in this i posted my code below. send.c /*filename : send.c *To compile : gcc send.c -o send */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> struct my_msgbuf { long mtype; char *mtext; }; int main(void) { struct my_msgbuf buf; int msqid; key_t key; static int count = 0; char temp[5]; int run = 1; if ((key = ftok("send.c", 'B')) == -1) { perror("ftok"); exit(1); } printf("send.c Key is = %d\n",key); if ((msqid = msgget(key, 0644 | IPC_CREAT)) == -1) { perror("msgget"); exit(1); } printf("Enter lines of text, ^D to quit:\n"); buf.mtype = 1; /* we don't really care in this case */ int ret = -1; while(run) { count++; buf.mtext = malloc(50); strcpy(buf.mtext,"Hi hello test message here"); snprintf(temp, sizeof (temp), "%d",count); strcat(buf.mtext,temp); int len = strlen(buf.mtext); /* ditch newline at end, if it exists */ if (buf.mtext[len-1] == '\n') buf.mtext[len-1] = '\0'; if (msgsnd(msqid, &buf, len+1, IPC_NOWAIT) == -1) /* +1 for '\0' */ perror("msgsnd"); if(count == 100) run = 0; usleep(1000000); } if (msgctl(msqid, IPC_RMID, NULL) == -1) { perror("msgctl"); exit(1); } return 0; } receive.c /* filename : receive.c * To compile : gcc receive.c -o receive */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> struct my_msgbuf { long mtype; char *mtext; }; int main(void) { struct my_msgbuf buf; int msqid; key_t key; if ((key = ftok("send.c", 'B')) == -1) { /* same key as send.c */ perror("ftok"); exit(1); } if ((msqid = msgget(key, 0644)) == -1) { /* connect to the queue */ perror("msgget"); exit(1); } printf("test: ready to receive messages, captain.\n"); for(;;) { /* receive never quits! */ buf.mtext = malloc(50); if (msgrcv(msqid, &buf, 50, 0, 0) == -1) { perror("msgrcv"); exit(1); } printf("test: \"%s\"\n", buf.mtext); } return 0; }

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  • Testing shared memory ,strange thing happen

    - by barfatchen
    I have 2 program compiled in 4.1.2 running in RedHat 5.5 , It is a simple job to test shared memory , shmem1.c like following : #define STATE_FILE "/program.shared" #define NAMESIZE 1024 #define MAXNAMES 100 typedef struct { char name[MAXNAMES][NAMESIZE]; int heartbeat ; int iFlag ; } SHARED_VAR; int main (void) { int first = 0; int shm_fd; static SHARED_VAR *conf; if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_EXCL | O_RDWR), (S_IREAD | S_IWRITE))) > 0 ) { first = 1; /* We are the first instance */ } else if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_RDWR), (S_IREAD | S_IWRITE))) < 0) { printf("Could not create shm object. %s\n", strerror(errno)); return errno; } if((conf = mmap(0, sizeof(SHARED_VAR), (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0)) == MAP_FAILED) { return errno; } if(first) { for(idx=0;idx< 1000000000;idx++) { conf->heartbeat = conf->heartbeat + 1 ; } } printf("conf->heartbeat=(%d)\n",conf->heartbeat) ; close(shm_fd); shm_unlink(STATE_FILE); exit(0); }//main And shmem2.c like following : #define STATE_FILE "/program.shared" #define NAMESIZE 1024 #define MAXNAMES 100 typedef struct { char name[MAXNAMES][NAMESIZE]; int heartbeat ; int iFlag ; } SHARED_VAR; int main (void) { int first = 0; int shm_fd; static SHARED_VAR *conf; if((shm_fd = shm_open(STATE_FILE, (O_RDWR), (S_IREAD | S_IWRITE))) < 0) { printf("Could not create shm object. %s\n", strerror(errno)); return errno; } ftruncate(shm_fd, sizeof(SHARED_VAR)); if((conf = mmap(0, sizeof(SHARED_VAR), (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0)) == MAP_FAILED) { return errno; } int idx ; for(idx=0;idx< 1000000000;idx++) { conf->heartbeat = conf->heartbeat + 1 ; } printf("conf->heartbeat=(%d)\n",conf->heartbeat) ; close(shm_fd); exit(0); } After compiled : gcc shmem1.c -lpthread -lrt -o shmem1.exe gcc shmem2.c -lpthread -lrt -o shmem2.exe And Run both program almost at the same time with 2 terminal : [test]$ ./shmem1.exe First creation of the shm. Setting up default values conf->heartbeat=(840825951) [test]$ ./shmem2.exe conf->heartbeat=(1215083817) I feel confused !! since shmem1.c is a loop 1,000,000,000 times , how can it be possible to have a answer like 840,825,951 ? I run shmem1.exe and shmem2.exe this way,most of the results are conf-heartbeat will larger than 1,000,000,000 , but seldom and randomly , I will see result conf-heartbeat will lesser than 1,000,000,000 , either in shmem1.exe or shmem2.exe !! if run shmem1.exe only , it is always print 1,000,000,000 , my question is , what is the reason cause conf-heartbeat=(840825951) in shmem1.exe ? Update: Although not sure , but I think I figure it out what is going on , If shmem1.exe run 10 times for example , then conf-heartbeat = 10 , in this time shmem1.exe take a rest and then back , shmem1.exe read from shared memory and conf-heartbeat = 8 , so shmem1.exe will continue from 8 , why conf-heartbeat = 8 ? I think it is because shmem2.exe update the shared memory data to 8 , shmem1.exe did not write 10 back to shared memory before it took a rest ....that is just my theory... i don't know how to prove it !!

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  • C string question

    - by user208454
    I am writing a simple c program which reverses a string, taking the string from argv[1]. Here is the code: #include <stdio.h> #include <stdlib.h> #include <string.h> char* flip_string(char *string){ int i = strlen(string); int j = 0; // Doesn't really matter all I wanted was the same size string for temp. char* temp = string; puts("This is the original string"); puts(string); puts("This is the \"temp\" string"); puts(temp); for(i; i>=0; i--){ temp[j] = string[i] if (j <= strlen(string)) { j++; } } return(temp); } int main(int argc, char *argv[]){ puts(flip_string(argv[1])); printf("This is the end of the program\n"); } That's basically it, the program compiles and everything but does not return the temp string in the end (just blank space). In the beginning it prints temp fine when its equal to string. Furthermore if I do a character by character printf of temp in the for loop the correct temp string in printed i.e. string - reversed. just when I try to print it to standard out (after the for loop/ or in the main) nothing happens only blank space is printed.

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  • Dynamic libraries are not allowed on iOS but what about this?

    - by tapirath
    I'm currently using LuaJIT and its FFI interface to call C functions from LUA scripts. What FFI does is to look at dynamic libraries' exported symbols and let the developer use it directly form LUA. Kind of like Python ctypes. Obviously using dynamic libraries is not permitted in iOS for security reasons. So in order to come up with a solution I found the following snippet. /* (c) 2012 +++ Filip Stoklas, aka FipS, http://www.4FipS.com +++ THIS CODE IS FREE - LICENSED UNDER THE MIT LICENSE ARTICLE URL: http://forums.4fips.com/viewtopic.php?f=3&t=589 */ extern "C" { #include <lua.h> #include <lualib.h> #include <lauxlib.h> } // extern "C" #include <cassert> // Please note that despite the fact that we build this code as a regular // executable (exe), we still use __declspec(dllexport) to export // symbols. Without doing that FFI wouldn't be able to locate them! extern "C" __declspec(dllexport) void __cdecl hello_from_lua(const char *msg) { printf("A message from LUA: %s\n", msg); } const char *lua_code = "local ffi = require('ffi') \n" "ffi.cdef[[ \n" "const char * hello_from_lua(const char *); \n" // matches the C prototype "]] \n" "ffi.C.hello_from_lua('Hello from LUA!') \n" // do actual C call ; int main() { lua_State *lua = luaL_newstate(); assert(lua); luaL_openlibs(lua); const int status = luaL_dostring(lua, lua_code); if(status) printf("Couldn't execute LUA code: %s\n", lua_tostring(lua, -1)); lua_close(lua); return 0; } // output: // A message from LUA: Hello from LUA! Basically, instead of using a dynamic library, the symbols are exported directly inside the executable file. The question is: is this permitted by Apple? Thanks.

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  • Brief pause after keypress

    - by user36324
    After i press and hold the key it goes forward once then pauses for a second or less then goes forward on forever. My problem is the brief pause I cant locate the issue. Thanks for your help. while(game){ while (SDL_PollEvent(&e)){ mainChar.manageEvents(e); } background.renderChar(); mainChar.renderChar(); SDL_RenderPresent(ren); } void Character::manageEvents(SDL_Event event) { switch(event.type){ case SDL_KEYDOWN: KEYS[event.key.keysym.sym] = true; printf("true"); handleInput(); break; case SDL_KEYUP: KEYS[event.key.keysym.sym] = false; printf("false"); break; default: break; } } void Character::handleInput() { if(KEYS[SDLK_a]) { dst.x--; } if(KEYS[SDLK_d]) { dst.x++; } if(KEYS[SDLK_w]) { dst.y++; } if(KEYS[SDLK_s]) { dst.y--; } }

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  • F# Application Entry Point

    - by MarkPearl
    Up to now I have been looking at F# for modular solutions, but have never considered writing an end to end application. Today I was wondering how one would even start to write an end to end application and realized that I didn’t even know where the entry point is for an F# application. After browsing MSDN a bit I got a basic example of a F# application with an entry point [<EntryPoint>] let main args = printfn "Arguments passed to function : %A" args // Return 0. This indicates success. 0 Pretty simple stuff… but what happens when you have a few modules in a program – so I created a F# project with two modules and a main module as illustrated in the image below… When I try to compile my program I get a build error… A function labeled with the 'EntryPointAttribute' attribute must be the last declaration in the last file in the compilation sequence, and can only be used when compiling to a .exe… What does this mean? After some more reading I discovered that the Program.fs needs to be the last file in the F# application – the order of the files in a F# solution are important. How do I move a source file up or down? I tried dragging the Program.fs file below ModuleB.fs but it wouldn’t allow me to. Then I thought to right click on a source file and got the following menu.   Wala… to move the source file to the bottom of the solution you can select the “Move Up” or “Move Down” option. Now that I got this right I decided to put some code in ModuleA & ModuleB and I have the start of a basic application structure. ModuleA Code namespace MyApp module ModuleA = let PrintModuleA = printf "hello a \n" ()   ModuleB Code namespace MyApp module ModuleB = let PrintModuleB = printf "hello b \n" ()   Program Code // Learn more about F# at http://fsharp.net #light namespace MyApp module Main = open System [<EntryPoint>] let main args = ModuleA.PrintModuleA let endofapp = Console.ReadKey() 0

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  • Simple C: atof giving wrong value [migrated]

    - by Doc
    I have a program that reads input from a singe line(string obviously) and organizes it into arrays. The problem I have is that at one point the program reads two different values and returns the first one twice. Initially I thought the program was reading the same value twice but when I tested it turned out that it got the correct one but is inputting the wrong one. for example Input: 2 0.90 0.75 0.7 0.65 sorry to snip it (while(fgets (string[test], sizeof(string[test]),ifp)) pch = strtok_r(NULL, " ", &prog); tem3 = atoi(pch); while (loop<tem3) { pch=strtok_r(NULL," ",&prog); venseatfloat[test][loop][DISCOUNT][OCCUPIED]=(float)atof(pch); printf("%f is discount\t",venseatfloat[test][loop][DISCOUNT][OCCUPIED]); pch=strtok_r(NULL, " ", &prog); strcpy(temp, pch); venseatfloat[test][loop][REGULAR][OCCUPIED]=(float)atof(pch); printf("%s is the string but %.3f is regular\n", temp ,venseatfloat[test][loop][DISCOUNT][OCCUPIED]); loop++; } output: >0.900000 is discount 0.75 is the string but 0.900 is regular >0.700000 is discount 0.65 is the string but 0.700 is regular What is going on?

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  • strlen returns incorrect value when called in gdb

    - by alesplin
    So I'm noticing some severely incorrect behavior from calls to standard library functions inside GDB. I have the following program to illustrate: #include <stdio.h> #include <stdlib.h> #include <string.h> int main(int argc, char *argv[]) { char *s1 = "test"; char *s2 = calloc(strlen("test")+1,sizeof(char)); snprintf(s2,strlen("test")+1,"test"); printf("string constant: %lu\n", strlen(s1)); printf("allocated string: %lu\n", strlen(s2)); free(s2); return 0; } When run from the command-line, this program outputs just what you'd expect: string constant: 4 allocated string: 4 However, in GDB, I get the following, incorrect output from calls to strlen(): (gdb) p strlen(s1) $1 = -938856896 (gdb) p strlen(s2) $2 = -938856896 I'm pretty sure this is a problem with glibc shipped with Ubuntu (I'm using 10.10), but this is a serious problem for those of us who spend lots of time in GDB. Is anyone else experiencing this kind of error? What's the best way to fix it? Build glibc from source? (I'm already running a version of GDB built from source)

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  • Is this buffer overflow working on Mac OSX? [migrated]

    - by cobie
    Was reading through some text and playing around with attempting to write past the size of an array in C i.e buffer overflow. The text indicates that whenever you attempt to write to say array[5] when the length of the array is 5 then you get a segmentation fault but I dont seem to be getting that When using the code below. The code actually runs. #include <stdio.h> #include <string.h> int main () { int i; int array[5] = {1, 2, 3, 4, 5}; for (i = 0; i <= 255; i++) { array[i] = 10; } int len = sizeof(array) / sizeof(int); printf("%d\n", len); printf("%d\n", array[254]); } On execution of the last statement, a 10 is printed. Am wondering whether this is a vulnerability or if there is something I am missing. I am running the code from iterm2 on a macbook pro.

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  • Object array updates one instance repeatedly [on hold]

    - by MGN001
    I'm making a 2D shooter, and the player object holds an array of bullets that represent how many shots the player can have on screen at once. At least, this is what I'm trying for. What's happening is that each time any of the objects in the array is called, it seems to update a single object in memory. So, if I fire and then fire again, the object "starts over" from where I shot from and moves twice as fast. I've spent weeks trying to fix this and I've managed nothing. Hopefully another pair of eyes will see something I've missed. Player.cpp #include "Player.h" const int startLives = 3; const int maxHealth = 2; const float speed = 1; const int maxVelocity = 500; const int topBound = WINDOW_HEIGHT / 5 * 3; const int slowRate = 500; const int accRate = 1000; const int maxBullets = 5; const float spriteWidth = 99; const float spriteHeight = 75; const Vector2f startPosition = { (WINDOW_WIDTH / 2) - (spriteWidth / 2), (WINDOW_HEIGHT / 4 * 3) - (spriteHeight / 2) }; Bullet bullets[maxBullets]; Bullet * bulletPointers[maxBullets]; SDL_Texture * playerHealthy; SDL_Texture * playerDamaged; SDL_Texture * currentSprite; SDL_Rect * rect; Vector2f position; Vector2f velocity; int Health; int Lives; Player::Player() { rect = new SDL_Rect(); } Player::~Player() { SDL_DestroyTexture(playerHealthy); SDL_DestroyTexture(playerDamaged); SDL_DestroyTexture(currentSprite); rect = NULL; } void Player::Initialize(SDL_Renderer * renderer) { SDL_Surface * temp; temp = IMG_Load(".\\Sprites\\player.png"); if (temp == NULL) { printf("Initialization Error: %s\n", IMG_GetError()); exit(PLAYER_INITIALIZATION_ERROR); } playerHealthy = SDL_CreateTextureFromSurface(renderer, temp); temp = IMG_Load(".\\Sprites\\playerDamaged.png"); if (temp == NULL) { printf("Initialization Error: %s\n", IMG_GetError()); exit(PLAYER_INITIALIZATION_ERROR); } playerDamaged = SDL_CreateTextureFromSurface(renderer, temp); temp = IMG_Load(".\\Sprites\\laserGreen.png"); if (temp == NULL) { printf("Initialization Error: %s\n", IMG_GetError()); exit(PLAYER_INITIALIZATION_ERROR); } SDL_Texture * bullet = SDL_CreateTextureFromSurface(renderer, temp); temp = IMG_Load(".\\Sprites\\laserGreenShot.png"); if (temp == NULL) { printf("Initialization Error: %s\n", IMG_GetError()); exit(PLAYER_INITIALIZATION_ERROR); } SDL_Texture * explosion = SDL_CreateTextureFromSurface(renderer, temp); for (int i = 0; i < maxBullets; i++) { bullets[i].Initialize(renderer, bullet, explosion); bulletPointers[i] = NULL; } temp = NULL; rect->h = spriteHeight; rect->w = spriteWidth; Reset(); } void Player::Update(Input input, float deltaTime) { if (abs(velocity.x) < slowRate * deltaTime) { velocity.x = 0; } else if (velocity.x > 0) { velocity.x -= slowRate * deltaTime; } else if (velocity.x < 0) { velocity.x += slowRate * deltaTime; } if (abs(velocity.y) < slowRate * deltaTime) { velocity.y = 0; } if (velocity.y > 0) { velocity.y -= slowRate * deltaTime; } else if (velocity.y < 0) { velocity.y += slowRate * deltaTime; } if (Health <= 0) { --Lives; Spawn(); } velocity.x += UnitVector(input.InputNew.movement).x * accRate * deltaTime; velocity.y += UnitVector(input.InputNew.movement).y * accRate * deltaTime; if (Magnitude(velocity) > maxVelocity) { velocity.x = UnitVector(velocity).x * maxVelocity; velocity.y = UnitVector(velocity).y * maxVelocity; } position.x += velocity.x * deltaTime * speed; position.y += velocity.y * deltaTime * speed; if (input.InputNew.JumpLeft && !input.InputOld.JumpLeft) { position.x -= spriteWidth; } if (input.InputNew.JumpRight && !input.InputOld.JumpRight) { position.x += spriteWidth; } Boundaries(); rect->x = position.x; rect->y = position.y; if (input.InputNew.Fire && !input.InputOld.Fire) { Fire(); } for (int i = 0; i < maxBullets; ++i) { if (bulletPointers[i] != NULL) { bullets[i].Update(deltaTime); if (bullets[i].getPosition().y < -33) { bulletPointers[i] = NULL; } } } } void Player::Draw(SDL_Renderer * renderer) { for (int i = 0; i < maxBullets; ++i) { if (bulletPointers[i] != NULL) { bullets[i].Draw(renderer); } } SDL_RenderCopy(renderer, currentSprite, NULL, rect); } void Player::Spawn() { position = startPosition; Health = maxHealth; currentSprite = playerHealthy; rect->x = position.x; rect->y = position.y; } void Player::Boundaries() { if (position.x < 0) { position.x = 0; velocity.x *= -1; } else if (position.x > WINDOW_WIDTH - spriteWidth) { position.x = WINDOW_WIDTH - spriteWidth; velocity.x *= -1; } if (position.y < topBound) { position.y = topBound; velocity.y *= -1; } else if (position.y > WINDOW_HEIGHT - spriteHeight) { position.y = WINDOW_HEIGHT - spriteHeight; velocity.y *= -1; } } int Player::getLives() { return Lives; } void Player::Reset() { Lives = startLives; Spawn(); } void Player::Fire() { for (int i = 0; i < maxBullets; ++i) { if (bulletPointers[i] == NULL) { bulletPointers[i] = &bullets[i]; bullets[i].Fire(position,velocity.x/2); break; } } } Bullet.cpp #include "Bullet.h" const int speed = 500; Vector2f bulletVelocity; float ExplosionMax = 0.5f; float ExplosionTimer; const Vector2f fireOffset = { 45.5f, 10.0f }; const Vector2f explosionOffset = { 23.5f, -27.0f }; const Vector2i bulletSize = { 9, 33 }; const Vector2i explosionSize = { 56, 54 }; Vector2f bulletPosition; SDL_Texture * bulletSprite; SDL_Texture * explosionSprite; SDL_Texture * bulletCurrentSprite; SDL_Rect * bulletRect; Bullet::Bullet() { } Bullet::~Bullet() { } void Bullet::Initialize(SDL_Renderer * renderer, SDL_Texture * bullet, SDL_Texture * explosion) { bulletSprite = bullet; explosionSprite = explosion; bulletRect = new SDL_Rect(); } void Bullet::Update(float deltaTime) { bulletPosition.y -= bulletVelocity.y * deltaTime; bulletPosition.x += bulletVelocity.x * deltaTime; bulletRect->x = static_cast<int>(bulletPosition.x); bulletRect->y = static_cast<int>(bulletPosition.y); } void Bullet::Draw(SDL_Renderer * renderer) { SDL_RenderCopy(renderer, bulletCurrentSprite, NULL, bulletRect); } void Bullet::Fire(Vector2f pos, float xSpeed) { bulletPosition.x = pos.x + fireOffset.x; bulletPosition.y = pos.y + fireOffset.y; bulletVelocity.x = xSpeed; bulletVelocity.y = speed; bulletCurrentSprite = bulletSprite; bulletRect->h = bulletSize.y; bulletRect->w = bulletSize.x; bulletRect->x = static_cast<int>(bulletPosition.x); bulletRect->y = static_cast<int>(bulletPosition.y); } Vector2f Bullet::getPosition() { return bulletPosition; } void Bullet::Hit() { bulletCurrentSprite = explosionSprite; bulletVelocity = { 0.0f, 0.0f }; ExplosionTimer = ExplosionMax; bulletPosition.x += explosionOffset.x; bulletPosition.y += explosionOffset.y; bulletRect->w = explosionSize.x; bulletRect->h = explosionSize.y; }

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  • Autocorrelation returns random results with mic input (using a high pass filter)

    - by Niall
    Hello, Sorry to ask a similar question to the one i asked before (FFT Problem (Returns random results)), but i've looked up pitch detection and autocorrelation and have found some code for pitch detection using autocorrelation. Im trying to do pitch detection of a users singing. Problem is, it keeps returning random results. I've got some code from http://code.google.com/p/yaalp/ which i've converted to C++ and modified (below). My sample rate is 2048, and data size is 1024. I'm detecting pitch of both a sine wave and mic input. The frequency of the sine wave is 726.0, and its detecting it to be 722.950820 (which im ok with), but its detecting the pitch of the mic as a random number from around 100 to around 1050. I'm now using a High pass filter to remove the DC offset, but it's not working. Am i doing it right, and if so, what else can i do to fix it? Any help would be greatly appreciated! double* doHighPassFilter(short *buffer) { // Do FFT: int bufferLength = 1024; float *real = malloc(bufferLength*sizeof(float)); float *real2 = malloc(bufferLength*sizeof(float)); for(int x=0;x<bufferLength;x++) { real[x] = buffer[x]; } fft(real, bufferLength); for(int x=0;x<bufferLength;x+=2) { real2[x] = real[x]; } for (int i=0; i < 30; i++) //Set freqs lower than 30hz to zero to attenuate the low frequencies real2[i] = 0; // Do inverse FFT: inversefft(real2,bufferLength); double* real3 = (double*)real2; return real3; } double DetectPitch(short* data) { int sampleRate = 2048; //Create sine wave double *buffer = malloc(1024*sizeof(short)); double amplitude = 0.25 * 32768; //0.25 * max length of short double frequency = 726.0; for (int n = 0; n < 1024; n++) { buffer[n] = (short)(amplitude * sin((2 * 3.14159265 * n * frequency) / sampleRate)); } doHighPassFilter(data); printf("Pitch from sine wave: %f\n",detectPitchCalculation(buffer, 50.0, 1000.0, 1, 1)); printf("Pitch from mic: %f\n",detectPitchCalculation(data, 50.0, 1000.0, 1, 1)); return 0; } // These work by shifting the signal until it seems to correlate with itself. // In other words if the signal looks very similar to (signal shifted 200 data) than the fundamental period is probably 200 data // Note that the algorithm only works well when there's only one prominent fundamental. // This could be optimized by looking at the rate of change to determine a maximum without testing all periods. double detectPitchCalculation(double* data, double minHz, double maxHz, int nCandidates, int nResolution) { //-------------------------1-------------------------// // note that higher frequency means lower period int nLowPeriodInSamples = hzToPeriodInSamples(maxHz, 2048); int nHiPeriodInSamples = hzToPeriodInSamples(minHz, 2048); if (nHiPeriodInSamples <= nLowPeriodInSamples) printf("Bad range for pitch detection."); if (1024 < nHiPeriodInSamples) printf("Not enough data."); double *results = new double[nHiPeriodInSamples - nLowPeriodInSamples]; //-------------------------2-------------------------// for (int period = nLowPeriodInSamples; period < nHiPeriodInSamples; period += nResolution) { double sum = 0; // for each sample, find correlation. (If they are far apart, small) for (int i = 0; i < 1024 - period; i++) sum += data[i] * data[i + period]; double mean = sum / 1024.0; results[period - nLowPeriodInSamples] = mean; } //-------------------------3-------------------------// // find the best indices int *bestIndices = findBestCandidates(nCandidates, results, nHiPeriodInSamples - nLowPeriodInSamples - 1); //note findBestCandidates modifies parameter // convert back to Hz double *res = new double[nCandidates]; for (int i=0; i < nCandidates;i++) res[i] = periodInSamplesToHz(bestIndices[i]+nLowPeriodInSamples, 2048); double pitch2 = res[0]; free(res); free(results); return pitch2; } /// Finds n "best" values from an array. Returns the indices of the best parts. /// (One way to do this would be to sort the array, but that could take too long. /// Warning: Changes the contents of the array!!! Do not use result array afterwards. int* findBestCandidates(int n, double* inputs,int length) { //int length = inputs.Length; if (length < n) printf("Length of inputs is not long enough."); int *res = new int[n]; double minValue = 0; for (int c = 0; c < n; c++) { // find the highest. double fBestValue = minValue; int nBestIndex = -1; for (int i = 0; i < length; i++) { if (inputs[i] > fBestValue) { nBestIndex = i; fBestValue = inputs[i]; } } // record this highest value res[c] = nBestIndex; // now blank out that index. if(nBestIndex!=-1) inputs[nBestIndex] = minValue; } return res; } int hzToPeriodInSamples(double hz, int sampleRate) { return (int)(1 / (hz / (double)sampleRate)); } double periodInSamplesToHz(int period, int sampleRate) { return 1 / (period / (double)sampleRate); } Thanks, Niall. Edit: Changed the code to implement a high pass filter with a cutoff of 30hz (from What Are High-Pass and Low-Pass Filters?, can anyone tell me how to convert the low-pass filter using convolution to a high-pass one?) but it's still returning random results. Plugging it into a VST host and using VST plugins to compare spectrums isn't an option to me unfortunately.

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  • Microbenchmark showing process-switching faster than thread-switching; what's wrong?

    - by Yang
    I have two simple microbenchmarks trying to measure thread- and process-switching overheads, but the process-switching overhead. The code is living here, and r1667 is pasted below: https://assorted.svn.sourceforge.net/svnroot/assorted/sandbox/trunk/src/c/process_switch_bench.c // on zs, ~2.1-2.4us/switch #include <stdlib.h> #include <fcntl.h> #include <stdint.h> #include <stdio.h> #include <semaphore.h> #include <unistd.h> #include <sys/wait.h> #include <sys/types.h> #include <sys/time.h> #include <pthread.h> uint32_t COUNTER; pthread_mutex_t LOCK; pthread_mutex_t START; sem_t *s0, *s1, *s2; void * threads ( void * unused ) { // Wait till we may fire away sem_wait(s2); for (;;) { pthread_mutex_lock(&LOCK); pthread_mutex_unlock(&LOCK); COUNTER++; sem_post(s0); sem_wait(s1); } return 0; } int64_t timeInMS () { struct timeval t; gettimeofday(&t, NULL); return ( (int64_t)t.tv_sec * 1000 + (int64_t)t.tv_usec / 1000 ); } int main ( int argc, char ** argv ) { int64_t start; pthread_t t1; pthread_mutex_init(&LOCK, NULL); COUNTER = 0; s0 = sem_open("/s0", O_CREAT, 0022, 0); if (s0 == 0) { perror("sem_open"); exit(1); } s1 = sem_open("/s1", O_CREAT, 0022, 0); if (s1 == 0) { perror("sem_open"); exit(1); } s2 = sem_open("/s2", O_CREAT, 0022, 0); if (s2 == 0) { perror("sem_open"); exit(1); } int x, y, z; sem_getvalue(s0, &x); sem_getvalue(s1, &y); sem_getvalue(s2, &z); printf("%d %d %d\n", x, y, z); pid_t pid = fork(); if (pid) { pthread_create(&t1, NULL, threads, NULL); pthread_detach(t1); // Get start time and fire away start = timeInMS(); sem_post(s2); sem_post(s2); // Wait for about a second sleep(1); // Stop thread pthread_mutex_lock(&LOCK); // Find out how much time has really passed. sleep won't guarantee me that // I sleep exactly one second, I might sleep longer since even after being // woken up, it can take some time before I gain back CPU time. Further // some more time might have passed before I obtained the lock! int64_t time = timeInMS() - start; // Correct the number of thread switches accordingly COUNTER = (uint32_t)(((uint64_t)COUNTER * 2 * 1000) / time); printf("Number of process switches in about one second was %u\n", COUNTER); printf("roughly %f microseconds per switch\n", 1000000.0 / COUNTER); // clean up kill(pid, 9); wait(0); sem_close(s0); sem_close(s1); sem_unlink("/s0"); sem_unlink("/s1"); sem_unlink("/s2"); } else { if (1) { sem_t *t = s0; s0 = s1; s1 = t; } threads(0); // never return } return 0; } https://assorted.svn.sourceforge.net/svnroot/assorted/sandbox/trunk/src/c/thread_switch_bench.c // From <http://stackoverflow.com/questions/304752/how-to-estimate-the-thread-context-switching-overhead> // on zs, ~4-5us/switch; tried making COUNTER updated only by one thread, but no difference #include <stdlib.h> #include <stdint.h> #include <stdio.h> #include <pthread.h> #include <unistd.h> #include <sys/time.h> uint32_t COUNTER; pthread_mutex_t LOCK; pthread_mutex_t START; pthread_cond_t CONDITION; void * threads ( void * unused ) { // Wait till we may fire away pthread_mutex_lock(&START); pthread_mutex_unlock(&START); int first=1; pthread_mutex_lock(&LOCK); // If I'm not the first thread, the other thread is already waiting on // the condition, thus Ihave to wake it up first, otherwise we'll deadlock if (COUNTER > 0) { pthread_cond_signal(&CONDITION); first=0; } for (;;) { if (first) COUNTER++; pthread_cond_wait(&CONDITION, &LOCK); // Always wake up the other thread before processing. The other // thread will not be able to do anything as long as I don't go // back to sleep first. pthread_cond_signal(&CONDITION); } pthread_mutex_unlock(&LOCK); return 0; } int64_t timeInMS () { struct timeval t; gettimeofday(&t, NULL); return ( (int64_t)t.tv_sec * 1000 + (int64_t)t.tv_usec / 1000 ); } int main ( int argc, char ** argv ) { int64_t start; pthread_t t1; pthread_t t2; pthread_mutex_init(&LOCK, NULL); pthread_mutex_init(&START, NULL); pthread_cond_init(&CONDITION, NULL); pthread_mutex_lock(&START); COUNTER = 0; pthread_create(&t1, NULL, threads, NULL); pthread_create(&t2, NULL, threads, NULL); pthread_detach(t1); pthread_detach(t2); // Get start time and fire away start = timeInMS(); pthread_mutex_unlock(&START); // Wait for about a second sleep(1); // Stop both threads pthread_mutex_lock(&LOCK); // Find out how much time has really passed. sleep won't guarantee me that // I sleep exactly one second, I might sleep longer since even after being // woken up, it can take some time before I gain back CPU time. Further // some more time might have passed before I obtained the lock! int64_t time = timeInMS() - start; // Correct the number of thread switches accordingly COUNTER = (uint32_t)(((uint64_t)COUNTER * 2 * 1000) / time); printf("Number of thread switches in about one second was %u\n", COUNTER); printf("roughly %f microseconds per switch\n", 1000000.0 / COUNTER); return 0; }

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  • Threading across multiple files

    - by Zach M.
    My program is reading in files and using thread to compute the highest prime number, when I put a print statement into the getNum() function my numbers are printing out. However, it seems to just lag no matter how many threads I input. Each file has 1 million integers in it. Does anyone see something apparently wrong with my code? Basically the code is giving each thread 1000 integers to check before assigning a new thread. I am still a C noobie and am just learning the ropes of threading. My code is a mess right now because I have been switching things around constantly. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> #include <pthread.h> #include <math.h> #include <semaphore.h> //Global variable declaration char *file1 = "primes1.txt"; char *file2 = "primes2.txt"; char *file3 = "primes3.txt"; char *file4 = "primes4.txt"; char *file5 = "primes5.txt"; char *file6 = "primes6.txt"; char *file7 = "primes7.txt"; char *file8 = "primes8.txt"; char *file9 = "primes9.txt"; char *file10 = "primes10.txt"; char **fn; //file name variable int numberOfThreads; int *highestPrime = NULL; int fileArrayNum = 0; int loop = 0; int currentFile = 0; sem_t semAccess; sem_t semAssign; int prime(int n)//check for prime number, return 1 for prime 0 for nonprime { int i; for(i = 2; i <= sqrt(n); i++) if(n % i == 0) return(0); return(1); } int getNum(FILE* file) { int number; char* tempS = malloc(20 *sizeof(char)); fgets(tempS, 20, file); tempS[strlen(tempS)-1] = '\0'; number = atoi(tempS); free(tempS);//free memory for later call return(number); } void* findPrimality(void *threadnum) //main thread function to find primes { int tNum = (int)threadnum; int checkNum; char *inUseFile = NULL; int x=1; FILE* file; while(currentFile < 10){ if(inUseFile == NULL){//inUseFIle being used to check if a file is still being read sem_wait(&semAccess);//critical section inUseFile = fn[currentFile]; sem_post(&semAssign); file = fopen(inUseFile, "r"); while(!feof(file)){ if(x % 1000 == 0 && tNum !=1){ //go for 1000 integers and then wait sem_wait(&semAssign); } checkNum = getNum(file); /* * * * * I think the issue is here * * * */ if(checkNum > highestPrime[tNum]){ if(prime(checkNum)){ highestPrime[tNum] = checkNum; } } x++; } fclose(file); inUseFile = NULL; } currentFile++; } } int main(int argc, char* argv[]) { if(argc != 2){ //checks for number of arguements being passed printf("To many ARGS\n"); return(-1); } else{//Sets thread cound to user input checking for correct number of threads numberOfThreads = atoi(argv[1]); if(numberOfThreads < 1 || numberOfThreads > 10){ printf("To many threads entered\n"); return(-1); } time_t preTime, postTime; //creating time variables int i; fn = malloc(10 * sizeof(char*)); //create file array and initialize fn[0] = file1; fn[1] = file2; fn[2] = file3; fn[3] = file4; fn[4] = file5; fn[5] = file6; fn[6] = file7; fn[7] = file8; fn[8] = file9; fn[9] = file10; sem_init(&semAccess, 0, 1); //initialize semaphores sem_init(&semAssign, 0, numberOfThreads); highestPrime = malloc(numberOfThreads * sizeof(int)); //create an array to store each threads highest number for(loop = 0; loop < numberOfThreads; loop++){//set initial values to 0 highestPrime[loop] = 0; } pthread_t calculationThread[numberOfThreads]; //thread to do the work preTime = time(NULL); //start the clock for(i = 0; i < numberOfThreads; i++){ pthread_create(&calculationThread[i], NULL, findPrimality, (void *)i); } for(i = 0; i < numberOfThreads; i++){ pthread_join(calculationThread[i], NULL); } for(i = 0; i < numberOfThreads; i++){ printf("this is a prime number: %d \n", highestPrime[i]); } postTime= time(NULL); printf("Wall time: %ld seconds\n", (long)(postTime - preTime)); } } Yes I am trying to find the highest number over all. So I have made some head way the last few hours, rescucturing the program as spudd said, currently I am getting a segmentation fault due to my use of structures, I am trying to save the largest individual primes in the struct while giving them the right indices. This is the revised code. So in short what the first thread is doing is creating all the threads and giving them access points to a very large integer array which they will go through and find prime numbers, I want to implement semaphores around the while loop so that while they are executing every 2000 lines or the end they update a global prime number. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> #include <pthread.h> #include <math.h> #include <semaphore.h> //Global variable declaration char *file1 = "primes1.txt"; char *file2 = "primes2.txt"; char *file3 = "primes3.txt"; char *file4 = "primes4.txt"; char *file5 = "primes5.txt"; char *file6 = "primes6.txt"; char *file7 = "primes7.txt"; char *file8 = "primes8.txt"; char *file9 = "primes9.txt"; char *file10 = "primes10.txt"; int numberOfThreads; int entries[10000000]; int entryIndex = 0; int fileCount = 0; char** fileName; int largestPrimeNumber = 0; //Register functions int prime(int n); int getNum(FILE* file); void* findPrimality(void *threadNum); void* assign(void *num); typedef struct package{ int largestPrime; int startingIndex; int numberCount; }pack; //Beging main code block int main(int argc, char* argv[]) { if(argc != 2){ //checks for number of arguements being passed printf("To many threads!!\n"); return(-1); } else{ //Sets thread cound to user input checking for correct number of threads numberOfThreads = atoi(argv[1]); if(numberOfThreads < 1 || numberOfThreads > 10){ printf("To many threads entered\n"); return(-1); } int threadPointer[numberOfThreads]; //Pointer array to point to entries time_t preTime, postTime; //creating time variables int i; fileName = malloc(10 * sizeof(char*)); //create file array and initialize fileName[0] = file1; fileName[1] = file2; fileName[2] = file3; fileName[3] = file4; fileName[4] = file5; fileName[5] = file6; fileName[6] = file7; fileName[7] = file8; fileName[8] = file9; fileName[9] = file10; FILE* filereader; int currentNum; for(i = 0; i < 10; i++){ filereader = fopen(fileName[i], "r"); while(!feof(filereader)){ char* tempString = malloc(20 *sizeof(char)); fgets(tempString, 20, filereader); tempString[strlen(tempString)-1] = '\0'; entries[entryIndex] = atoi(tempString); entryIndex++; free(tempString); } } //sem_init(&semAccess, 0, 1); //initialize semaphores //sem_init(&semAssign, 0, numberOfThreads); time_t tPre, tPost; pthread_t coordinate; tPre = time(NULL); pthread_create(&coordinate, NULL, assign, (void**)numberOfThreads); pthread_join(coordinate, NULL); tPost = time(NULL); } } void* findPrime(void* pack_array) { pack* currentPack= pack_array; int lp = currentPack->largestPrime; int si = currentPack->startingIndex; int nc = currentPack->numberCount; int i; int j = 0; for(i = si; i < nc; i++){ while(j < 2000 || i == (nc-1)){ if(prime(entries[i])){ if(entries[i] > lp) lp = entries[i]; } j++; } } return (void*)currentPack; } void* assign(void* num) { int y = (int)num; int i; int count = 10000000/y; int finalCount = count + (10000000%y); int sIndex = 0; pack pack_array[(int)num]; pthread_t workers[numberOfThreads]; //thread to do the workers for(i = 0; i < y; i++){ if(i == (y-1)){ pack_array[i].largestPrime = 0; pack_array[i].startingIndex = sIndex; pack_array[i].numberCount = finalCount; } pack_array[i].largestPrime = 0; pack_array[i].startingIndex = sIndex; pack_array[i].numberCount = count; pthread_create(&workers[i], NULL, findPrime, (void *)&pack_array[i]); sIndex += count; } for(i = 0; i< y; i++) pthread_join(workers[i], NULL); } //Functions int prime(int n)//check for prime number, return 1 for prime 0 for nonprime { int i; for(i = 2; i <= sqrt(n); i++) if(n % i == 0) return(0); return(1); }

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  • Tip #13 java.io.File Surprises

    - by ByronNevins
    There is an assumption that I've seen in code many times that is totally wrong.  And this assumption can easily bite you.  The assumption is: File.getAbsolutePath and getAbsoluteFile return paths that are not relative.  Not true!  Sort of.  At least not in the way many people would assume.  All they do is make sure that the beginning of the path is absolute.  The rest of the path can be loaded with relative path elements.  What do you think the following code will print? public class Main {    public static void main(String[] args) {        try {            File f = new File("/temp/../temp/../temp/../");            File abs  = f.getAbsoluteFile();            File parent = abs.getParentFile();            System.out.println("Exists: " + f.exists());            System.out.println("Absolute Path: " + abs);            System.out.println("FileName: " + abs.getName());            System.out.printf("The Parent Directory of %s is %s\n", abs, parent);            System.out.printf("The CANONICAL Parent Directory of CANONICAL %s is %s\n",                        abs, abs.getCanonicalFile().getParent());            System.out.printf("The CANONICAL Parent Directory of ABSOLUTE %s is %s\n",                        abs, parent.getCanonicalFile());            System.out.println("Canonical Path: " + f.getCanonicalPath());        }        catch (IOException ex) {            System.out.println("Got an exception: " + ex);        }    }} Output: Exists: trueAbsolute Path: D:\temp\..\temp\..\temp\..FileName: ..The Parent Directory of D:\temp\..\temp\..\temp\.. is D:\temp\..\temp\..\tempThe CANONICAL Parent Directory of CANONICAL D:\temp\..\temp\..\temp\.. is nullThe CANONICAL Parent Directory of ABSOLUTE D:\temp\..\temp\..\temp\.. is D:\tempCanonical Path: D:\ Notice how it says that the parent of d:\ is d:\temp !!!The file, f, is really the root directory.  The parent is supposed to be null. I learned about this the hard way! getParentXXX simply hacks off the final item in the path. You can get totally unexpected results like the above. Easily. I filed a bug on this behavior a few years ago[1].   Recommendations: (1) Use getCanonical instead of getAbsolute.  There is a 1:1 mapping of files and canonical filenames.  I.e each file has one and only one canonical filename and it will definitely not have relative path elements in it.  There are an infinite number of absolute paths for each file. (2) To get the parent file for File f do the following instead of getParentFile: File parent = new File(f, ".."); [1] http://bt2ws.central.sun.com/CrPrint?id=6687287

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  • Basic shadow mapping fails on NVIDIA card?

    - by James
    Recently I switched from an AMD Radeon HD 6870 card to an (MSI) NVIDIA GTX 670 for performance reasons. I found however that my implementation of shadow mapping in all my applications failed. In a very simple shadow POC project the problem appears to be that the scene being drawn never results in a draw to the depth map and as a result the entire depth map is just infinity, 1.0 (Reading directly from the depth component after draw (glReadPixels) shows every pixel is infinity (1.0), replacing the depth comparison in the shader with a comparison of the depth from the shadow map with 1.0 shadows the entire scene, and writing random values to the depth map and then not calling glClear(GL_DEPTH_BUFFER_BIT) results in a random noisy pattern on the scene elements - from which we can infer that the uploading of the depth texture and comparison within the shader are functioning perfectly.) Since the problem appears almost certainly to be in the depth render, this is the code for that: const int s_res = 1024; GLuint shadowMap_tex; GLuint shadowMap_prog; GLint sm_attr_coord3d; GLint sm_uniform_mvp; GLuint fbo_handle; GLuint renderBuffer; bool isMappingShad = false; //The scene consists of a plane with box above it GLfloat scene[] = { -10.0, 0.0, -10.0, 0.5, 0.0, 10.0, 0.0, -10.0, 1.0, 0.0, 10.0, 0.0, 10.0, 1.0, 0.5, -10.0, 0.0, -10.0, 0.5, 0.0, -10.0, 0.0, 10.0, 0.5, 0.5, 10.0, 0.0, 10.0, 1.0, 0.5, ... }; //Initialize the stuff used by the shadow map generator int initShadowMap() { //Initialize the shadowMap shader program if (create_program("shadow.v.glsl", "shadow.f.glsl", shadowMap_prog) != 1) return -1; const char* attribute_name = "coord3d"; sm_attr_coord3d = glGetAttribLocation(shadowMap_prog, attribute_name); if (sm_attr_coord3d == -1) { fprintf(stderr, "Could not bind attribute %s\n", attribute_name); return 0; } const char* uniform_name = "mvp"; sm_uniform_mvp = glGetUniformLocation(shadowMap_prog, uniform_name); if (sm_uniform_mvp == -1) { fprintf(stderr, "Could not bind uniform %s\n", uniform_name); return 0; } //Create a framebuffer glGenFramebuffers(1, &fbo_handle); glBindFramebuffer(GL_FRAMEBUFFER, fbo_handle); //Create render buffer glGenRenderbuffers(1, &renderBuffer); glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer); //Setup the shadow texture glGenTextures(1, &shadowMap_tex); glBindTexture(GL_TEXTURE_2D, shadowMap_tex); glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, s_res, s_res, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); return 0; } //Delete stuff void dnitShadowMap() { //Delete everything glDeleteFramebuffers(1, &fbo_handle); glDeleteRenderbuffers(1, &renderBuffer); glDeleteTextures(1, &shadowMap_tex); glDeleteProgram(shadowMap_prog); } int loadSMap() { //Bind MVP stuff glm::mat4 view = glm::lookAt(glm::vec3(10.0, 10.0, 5.0), glm::vec3(0.0, 0.0, 0.0), glm::vec3(0.0, 1.0, 0.0)); glm::mat4 projection = glm::ortho<float>(-10,10,-8,8,-10,40); glm::mat4 mvp = projection * view; glm::mat4 biasMatrix( 0.5, 0.0, 0.0, 0.0, 0.0, 0.5, 0.0, 0.0, 0.0, 0.0, 0.5, 0.0, 0.5, 0.5, 0.5, 1.0 ); glm::mat4 lsMVP = biasMatrix * mvp; //Upload light source matrix to the main shader programs glUniformMatrix4fv(uniform_ls_mvp, 1, GL_FALSE, glm::value_ptr(lsMVP)); glUseProgram(shadowMap_prog); glUniformMatrix4fv(sm_uniform_mvp, 1, GL_FALSE, glm::value_ptr(mvp)); //Draw to the framebuffer (with depth buffer only draw) glBindFramebuffer(GL_FRAMEBUFFER, fbo_handle); glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer); glBindTexture(GL_TEXTURE_2D, shadowMap_tex); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, shadowMap_tex, 0); glDrawBuffer(GL_NONE); glReadBuffer(GL_NONE); GLenum result = glCheckFramebufferStatus(GL_FRAMEBUFFER); if (GL_FRAMEBUFFER_COMPLETE != result) { printf("ERROR: Framebuffer is not complete.\n"); return -1; } //Draw shadow scene printf("Creating shadow buffers..\n"); int ticks = SDL_GetTicks(); glClear(GL_DEPTH_BUFFER_BIT); //Wipe the depth buffer glViewport(0, 0, s_res, s_res); isMappingShad = true; //DRAW glEnableVertexAttribArray(sm_attr_coord3d); glVertexAttribPointer(sm_attr_coord3d, 3, GL_FLOAT, GL_FALSE, 5*4, scene); glDrawArrays(GL_TRIANGLES, 0, 14*3); glDisableVertexAttribArray(sm_attr_coord3d); isMappingShad = false; glBindFramebuffer(GL_FRAMEBUFFER, 0); printf("Render Sbuf in %dms (GLerr: %d)\n", SDL_GetTicks() - ticks, glGetError()); return 0; } This is the full code for the POC shadow mapping project (C++) (Requires SDL 1.2, SDL-image 1.2, GLEW (1.5) and GLM development headers.) initShadowMap is called, followed by loadSMap, the scene is drawn from the camera POV and then dnitShadowMap is called. I followed this tutorial originally (Along with another more comprehensive tutorial which has disappeared as this guy re-configured his site but used to be here (404).) I've ensured that the scene is visible (as can be seen within the full project) to the light source (which uses an orthogonal projection matrix.) Shader utilities function fine in non-shadow-mapped projects. I should also note that at no point is the GL error state set. What am I doing wrong here and why did this not cause problems on my AMD card? (System: Ubuntu 12.04, Linux 3.2.0-49-generic, 64 bit, with the nvidia-experimental-310 driver package. All other games are functioning fine so it's most likely not a card/driver issue.)

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  • how to clear stack after stack overflow signal occur

    - by user353573
    In pthread, After reaching yellow zone in stack, signal handler stop the recursive function by making it return however, we can only continue to use extra area in yellow zone, how to clear the rubbish before the yellow zone in the thread stack ? (Copied from "answers"): #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <setjmp.h> #include <sys/mman.h> #include <unistd.h> #include <assert.h> #include <sys/resource.h> #define ALT_STACK_SIZE (64*1024) #define YELLOW_ZONE_PAGES (1) typedef struct { size_t stack_size; char* stack_pointer; char* red_zone_boundary; char* yellow_zone_boundary; sigjmp_buf return_point; size_t red_zone_size; } ThreadInfo; static pthread_key_t thread_info_key; static struct sigaction newAct, oldAct; bool gofromyellow = false; int call_times = 0; static void main_routine(){ // make it overflow if(gofromyellow == true) { printf("return from yellow zone, called %d times\n", call_times); return; } else { call_times = call_times + 1; main_routine(); gofromyellow = true; } } // red zone management static void stackoverflow_routine(){ fprintf(stderr, "stack overflow error.\n"); fflush(stderr); } // yellow zone management static void yellow_zone_hook(){ fprintf(stderr, "exceed yellow zone.\n"); fflush(stderr); } static int get_stack_info(void** stackaddr, size_t* stacksize){ int ret = -1; pthread_attr_t attr; pthread_attr_init(&attr); if(pthread_getattr_np(pthread_self(), &attr) == 0){ ret = pthread_attr_getstack(&attr, stackaddr, stacksize); } pthread_attr_destroy(&attr); return ret; } static int is_in_stack(const ThreadInfo* tinfo, char* pointer){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->stack_pointer + tinfo->stack_size); } static int is_in_red_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->red_zone_boundary){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->red_zone_boundary); } } static int is_in_yellow_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->yellow_zone_boundary){ return (tinfo->red_zone_boundary <= pointer) && (pointer < tinfo->yellow_zone_boundary); } } static void set_yellow_zone(ThreadInfo* tinfo){ int pagesize = sysconf(_SC_PAGE_SIZE); assert(pagesize > 0); tinfo->yellow_zone_boundary = tinfo->red_zone_boundary + pagesize * YELLOW_ZONE_PAGES; mprotect(tinfo->red_zone_boundary, pagesize * YELLOW_ZONE_PAGES, PROT_NONE); } static void reset_yellow_zone(ThreadInfo* tinfo){ size_t pagesize = tinfo->yellow_zone_boundary - tinfo->red_zone_boundary; if(mmap(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0) == 0){ perror("mmap failed"), exit(1); } mprotect(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE); tinfo->yellow_zone_boundary = 0; } static void signal_handler(int sig, siginfo_t* sig_info, void* sig_data){ if(sig == SIGSEGV){ ThreadInfo* tinfo = (ThreadInfo*) pthread_getspecific(thread_info_key); char* fault_address = (char*) sig_info->si_addr; if(is_in_stack(tinfo, fault_address)){ if(is_in_red_zone(tinfo, fault_address)){ siglongjmp(tinfo->return_point, 1); }else if(is_in_yellow_zone(tinfo, fault_address)){ reset_yellow_zone(tinfo); yellow_zone_hook(); gofromyellow = true; return; } else { //inside stack not related overflow SEGV happen } } } } static void register_application_info(){ pthread_key_create(&thread_info_key, NULL); sigemptyset(&newAct.sa_mask); sigaddset(&newAct.sa_mask, SIGSEGV); newAct.sa_sigaction = signal_handler; newAct.sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK; sigaction(SIGSEGV, &newAct, &oldAct); } static void register_thread_info(ThreadInfo* tinfo){ stack_t ss; pthread_setspecific(thread_info_key, tinfo); get_stack_info((void**)&tinfo->stack_pointer, &tinfo->stack_size); printf("stack size %d mb\n", tinfo->stack_size/1024/1024 ); tinfo->red_zone_boundary = tinfo->stack_pointer + tinfo->red_zone_size; set_yellow_zone(tinfo); ss.ss_sp = (char*)malloc(ALT_STACK_SIZE); ss.ss_size = ALT_STACK_SIZE; ss.ss_flags = 0; sigaltstack(&ss, NULL); } static void* thread_routine(void* p){ ThreadInfo* tinfo = (ThreadInfo*)p; register_thread_info(tinfo); if(sigsetjmp(tinfo->return_point, 1) == 0){ main_routine(); } else { stackoverflow_routine(); } free(tinfo); printf("after tinfo, end thread\n"); return 0; } int main(int argc, char** argv){ register_application_info(); if( argc == 2 ){ int stacksize = atoi(argv[1]); pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 1024 * 1024 * stacksize); { pthread_t pid0; ThreadInfo* tinfo = (ThreadInfo*)calloc(1, sizeof(ThreadInfo)); pthread_attr_getguardsize(&attr, &tinfo->red_zone_size); pthread_create(&pid0, &attr, thread_routine, tinfo); pthread_join(pid0, NULL); } } else { printf("Usage: %s stacksize(mb)\n", argv[0]); } return 0; } C language in linux, ubuntu

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  • iPhone: ASIFormDataRequest Returns NULL from PHP Server

    - by meetS
    Hi, I have PHP script link, which responds YES or NO when we set post userName and emailID. I have used ASI framework. When I try to connect with the following code, I get a null return. NSURL *url = [NSURL URLWithString:@"https://abc.com/abctest/registration.php"]; ASIFormDataRequest *request = [[ASIFormDataRequest alloc] initWithURL:url]; [request setPostValue:@"[email protected]" forKey:@"email"]; [request setPostValue:@"pqr" forKey:@"userName"]; [request start]; NSError *error = [request error]; if (!error) { NSString *response = [request responseString]; printf("\n\n\n Responce %s",[response UTF8String]); response = [response stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]; if ([response isEqualToString:@"YES"]) { printf("\n\n YES"); } } What am I doing wrong?

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  • SHELL OR PERL QUESTION

    - by user150674
    I have a very large file, named 'ColCheckMe', tab-delimited, that you are asked to process. You are told that each line in 'ColCheckMe' has 7 columns, and that the values in the 5th column are integers. Using shell functions indicate how you would verify that these conditions were satisfied in 'ColCheckMe' K got this... nawk ‘ NF != 7 { Printf(“[%d] has invalid [%d] number of fileds\n”, FNR, NF) } $5 !~ /^[0-9]+$/ { Printf(“[%d] 5th field is invalid [%s]\n”, FNR, $5) }’ ColCheckMe Now, 2. In with the similar file, you are told that each value in column 1 is unique. How would I verify that? Also write a shell function that counts the number of occurrences of the word “SpecStr” in the file 'ColCheckMe' Any one can help in SHELL or everything including the first in PERL Scripting.

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  • Problem using void pointer as a function argument

    - by Nazgulled
    Hi, I can't understand this result... The code: void foo(void * key, size_t key_sz) { HashItem *item = malloc(sizeof(HashItem)); printf("[%d]\n", (int)key); ... item->key = malloc(key_sz); memcpy(item->key, key, key_sz); } void bar(int num) { foo(&num, sizeof(int)); } And I do this call: bar(900011009); But the printf() output is: [-1074593956] I really need key to be a void pointer, how can I fix this?

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  • PHP and Objective C Communication

    - by meetS
    Hii, I have PHP script link,which responds YES or NO when we set post userName and emailID.I have used ASI framework. But it is not working....Here is my code....Thanks in advance... **NSURL *url = [NSURL URLWithString:@"https://abc.com/abctest/registration.php"]; ASIFormDataRequest *request = [[ASIFormDataRequest alloc] initWithURL:url]; [request setPostValue:@"[email protected]" forKey:@"email"]; [request setPostValue:@"pqr" forKey:@"ebayName"]; [request start]; NSError *error = [request error]; if (!error) { NSString *response = [request responseString]; printf("\n\n\n Responce %s",[response UTF8String]); response = [response stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]; if ([response isEqualToString:@"YES"]) { printf("\n\n YES"); } }

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  • Objective-c Novice - Needs help with string with variable

    - by user544006
    Im trying to get my label to print out "your score is ." All i can find online is how to print using printf: int score=2; printf("You scored %i", score); But this does not work when using the setText method. I have also tried labelAnswer.setText:("You scored %i", score); [labelAnswer setText:("You scored %i", score)]; But these do not work. I get an error: "request for member in something not a structure or union" Can anyone help?

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  • how to find if the machine is 32bit or 64bit

    - by prabodh
    Is there anyway from a C prog to find whether the OS is currently running in 32bit or 64bit mode. I am using a simple program as below int main(void){ switch(sizeof(void*)){ case 4: printf("32\n"); break; case 8: printf("64\n"); break; } } Is this a correct approach ? Would this code work in all the scenarios like, If the hardware is 64bit and the OS is 32bit what would it return ? I don't have machine to test this in diff configurations. Thanks for the advice.

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  • Regarding to get refrence of IDot11AdHocManager Interface of COM WiFi AdHoc manager Interface

    - by sathaliyawala
    I am Trying to create AdHoc connection and for this i am using AdHoc wifi Interface provided by Microsoft. I have written code :- IDot11AdHocManager *pIAdHocMng = NULL ; HRESULT hr = CoInitialize(NULL); hr = CoCreateInstance(CLSID_Dot11AdHocManager,NULL,CLSCTX_INPROC_HANDLER ,IID_IDot11AdHocManager ,(void**)pIAdHocMng); if(hr == S_OK) printf("CreateNetwork Method success due to following reason :\n %ld",hr) ; else printf("CreateNetwork Method fail due to following reason : %ld \n ",hr) ; getch(); CoUninitialize(); But it will not return reference of Dot11AdHocManager it will return error and NULL value please help me to get the reference of Dot11AdHocManager Interface so i can use it method which help me to create the AdHoc Network

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  • Reading In A String and comparing it C

    - by ahref
    Im trying to create a C based string menu where a user inputs a command and then a block of code runs. Whatever i do the conditional is never true: char *input= ""; fgets(input, 50, stdin); printf("%s",input); printf("%d",strcmp( input,"arrive\0")); if(strcmp( input,"arrive\0")==0){.... Im fairly new to c and am finding strings really annoying. What am i doing wrong?

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  • vss intializefor backup fails with return code E_UNEXPECTED

    - by suresh
    #include "vss.h" #include "vswriter.h" #include <VsBackup.h> #include <stdio.h> #define CHECK_PRINT(result) printf("%s\n",result==S_OK?"S_OK":"error") int main(int argc, char* argv[]) { BSTR xml; LPTSTR errorText; IVssBackupComponents *VssHandle; HRESULT result = CreateVssBackupComponents(&VssHandle); CHECK_PRINT(result); result = VssHandle->InitializeForBackup(); printf("unexpected%x\n",result); system("pause"); return 0; } in the above program intializeforbackup fails with error code E_UNEXPECTED. The VSS service is running . In the event log it shows as "Volume Shadow Copy Service error: Unexpected error calling routine CoCreateInstance. hr = 0x800401f0.".. Any solutions for the InitializeForBackup to return S_OK?

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