initial commit

Author: Solarian

README

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+Here you could find the code for "C++11 thread tutorial", for more informations visit the project webpage:
+
+http://solarianprogrammer.com/2011/12/16/cpp-11-thread-tutorial/
+
+In order to use the image_processing code you will need a picture in ppm format, you can easily find examples 
+on the Internet, or you could use Gimp to save your own picture in ppm format.
+
+You could use this program under the terms of GPL v3, for more details see:
+
+http://www.gnu.org/copyleft/gpl.html
+
+Copyright 2011 Sol from www.solarianprogrammer.com

cpp_thread_00.cpp

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+//Create a C++11 thread from the main program
+
+
+#include <iostream>
+#include <thread>
+
+using namespace std;
+
+//This function will be called from a thread
+void call_from_thread(){
+	cout<<"Launched by thread"<<endl;
+}
+
+
+int main(){
+	//Launch a thread
+	thread t1 = thread(call_from_thread);
+	
+	//Join the thread with the main thread
+	t1.join();
+	return(0);
+}

cpp_thread_01.cpp

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+//Create a group of C++11 threads from the main program
+
+#include <iostream>
+#include <thread>
+
+using namespace std;
+
+#define NUM_THREADS 10
+
+//This function will be called from a thread
+void call_from_thread(){
+	cout<<"Launched by thread\n";
+}
+
+int main(){
+	thread *t = new thread[NUM_THREADS];
+
+	//Launch a group of threads
+	for(int i=0;i<NUM_THREADS;i++){
+		t[i] = thread(call_from_thread);
+	}
+	
+	cout<<"Launched from the main\n";
+		
+	//Join the threads with the main thread
+	for(int i=0;i<NUM_THREADS;i++){
+		t[i].join();
+	}
+
+	delete [] t;
+	return(0);
+}

cpp_thread_02.cpp

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+//Create a group of C++11 threads from the main program
+
+#include <iostream>
+#include <thread>
+
+using namespace std;
+
+#define NUM_THREADS 10
+
+//This function will be called from a thread
+void call_from_thread(int tid){
+	cout<<"Launched by thread "<<tid<<endl;
+}
+
+int main(){
+	thread *t = new thread[NUM_THREADS];
+
+	//Launch a group of threads
+	for(int i=0;i<NUM_THREADS;i++){
+		t[i] = thread(call_from_thread,i);
+	}
+	
+	cout<<"Launched from the main\n";
+		
+	//Join the threads with the main thread
+	for(int i=0;i<NUM_THREADS;i++){
+		t[i].join();
+	}
+
+	delete [] t;
+	return(0);
+}

image_processing/ppm.cpp

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+#include <iostream>
+#include <fstream>
+#include <string>
+#include <sstream>
+#include <exception>
+
+#include "ppm.h"
+
+//init with default values
+void ppm::init(){
+	flag_alloc = false;
+	width=0;
+	height=0;
+	max_col_val=255;	
+}
+
+//create a PPM object
+ppm::ppm(){
+	init();
+}
+
+//create a PPM object and fill it with data stored in fname 
+ppm::ppm(const std::string &fname){
+	init();
+	read(fname);
+}
+
+//create an "epmty" PPM image with a given width and height;the R,G,B arrays are filled with zeros
+ppm::ppm(const unsigned int _width, const unsigned int _height){
+	init();
+	width = _width;
+	height = _height;
+	nr_lines = height;
+	nr_columns = width;
+	size = width*height;
+
+	r = new unsigned char[size];
+	g = new unsigned char[size];
+	b = new unsigned char[size];
+	flag_alloc = true;
+
+	for(unsigned int i = 0; i < size; i++){
+		r[i] = 0;
+		g[i] = 0;
+		b[i] = 0;			
+	}
+}
+
+//free the memory used by the R,G,B vectors when the object is destroyed
+ppm::~ppm(){
+	if(flag_alloc){
+		delete [] r;
+		delete [] g;
+		delete [] b;
+	}
+}
+
+//read the PPM image from fname
+void ppm::read(const std::string &fname){	
+	std::ifstream inp(fname.c_str(), std::ios::in|std::ios::binary);
+	if(inp.is_open()){
+		std::string line;
+		std::getline(inp,line);
+		if(line != "P6"){
+			std::cout<<"Error. Unrecognized file format."<<std::endl;
+			return;
+		}
+		std::getline(inp,line);
+		while(line[0]=='#'){
+			std::getline(inp,line);
+		}
+		std::stringstream dimensions(line);
+
+		try{
+			dimensions>>width;
+			dimensions>>height;
+			nr_lines = height;
+			nr_columns = width;
+		}
+		catch(std::exception &e){
+			std::cout<<"Header file format error. "<<e.what()<<std::endl;
+			return;
+		}
+
+		std::getline(inp,line);
+		std::stringstream max_val(line);
+		try{
+			max_val>>max_col_val;
+		}
+		catch(std::exception &e){
+			std::cout<<"Header file format error. "<<e.what()<<std::endl;
+			return;
+		}
+
+		size = width*height;
+
+		r = new unsigned char[size];
+		g = new unsigned char[size];
+		b = new unsigned char[size];
+		flag_alloc = true;
+
+		char aux;
+		for(unsigned int i = 0; i < size; i++){
+			inp.read(&aux,1);
+			r[i] = (unsigned char) aux;
+			inp.read(&aux,1);
+			g[i] = (unsigned char) aux;
+			inp.read(&aux,1);
+			b[i] = (unsigned char) aux;			
+		}
+	}
+	else{
+		std::cout<<"Error. Unable to open "<<fname<<std::endl;
+	}
+	inp.close();	
+}
+
+//write the PPM image in fname
+void ppm::write(const std::string &fname){	
+	std::ofstream inp(fname.c_str(), std::ios::out|std::ios::binary);
+	if(inp.is_open()){
+		
+		inp<<"P6\n";
+		inp<<width;
+		inp<<" ";
+		inp<<height<<"\n";
+		inp<<max_col_val<<"\n";
+
+		char aux;
+		for(unsigned int i = 0; i < size; i++){
+			aux = (char)r[i];
+			inp.write(&aux,1);
+			aux = (char)g[i];
+			inp.write(&aux,1);
+			aux = (char)b[i];
+			inp.write(&aux,1);			
+		}
+	}
+	else{
+		std::cout<<"Error. Unable to open "<<fname<<std::endl;
+	}
+	inp.close();	
+}
+

image_processing/ppm.h

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+//Process a binary PPM file
+class ppm{
+	bool flag_alloc;
+	void init();
+	//info about the PPM file (height and width)
+	unsigned int nr_lines;
+	unsigned int nr_columns;
+
+public:
+	//arrays for storing the R,G,B values
+	unsigned char *r;
+	unsigned char *g;
+	unsigned char *b;
+	//
+	unsigned int height;
+	unsigned int width;
+	unsigned int max_col_val;
+	//total number of elements (pixels)
+	unsigned int size;
+
+	ppm();
+	//create a PPM object and fill it with data stored in fname 
+	ppm(const std::string &fname);
+	//create an "epmty" PPM image with a given width and height;the R,G,B arrays are filled with zeros
+	ppm(const unsigned int _width, const unsigned int _height);
+	//free the memory used by the R,G,B vectors when the object is destroyed
+	~ppm();
+	//read the PPM image from fname
+	void read(const std::string &fname);
+	//write the PPM image in fname
+	void write(const std::string &fname);
+};