diff --git a/lab4/src/threads/threading b/lab4/src/threads/threading
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index 0000000..5ae8700
Binary files /dev/null and b/lab4/src/threads/threading differ
diff --git a/lab4/src/threads/threading.cpp b/lab4/src/threads/threading.cpp
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+++ b/lab4/src/threads/threading.cpp
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+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <cstdint>
+#include "important.h"
+#include <pthread.h>
+#include <iostream>
+#include <chrono>
+#include <fstream>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+using namespace std;
+
+int current_index = 0;
+int sum;
+struct image_t* input_image;
+struct image_t* smoother;
+struct image_t* details;
+struct image_t* sharp;
+int a = 1;
+
+int lock1 = 0; // initial lock set
+int lock2 = 1; // initial lock set
+int lock3 = 0; // initial lock set
+int lock4 = 1; // initial lock set
+
+int pt = 1;
+int pt1 = 1;
+
+void* S1_smoothen(void* thread_number)
+{
+    int my_number = *(int *)thread_number;
+	//cout << input_image->width << input_image->height << " " <<  input_image->image_pixels << endl;
+	int width = input_image->width;
+	int height = input_image->height;
+	
+	// memory allocation
+	// struct image_t* smoother = new struct image_t;
+    for(pt = 1; pt <= 1000; ++pt) {
+        while(__sync_lock_test_and_set(&lock1,1));
+        printf("thread number : %d\tindex : %d\n", my_number, pt);
+        for(int i = 1; i < height-1; i++)
+        {
+            for(int j = 1; j < width-1; j++)
+            {
+                for(int k = 0; k < 3; k++)
+                {
+                    //image->image_pixels[i][j][k] = val;
+                    // edge cases
+                    if(i == 0 && j == 0) { // i-1 and j - 1 doesnt exist
+                        smoother->image_pixels[i][j][k] =  ( input_image->image_pixels[i][j][k] / 9+  input_image->image_pixels[i][j+1][k] / 9 +  input_image->image_pixels[i+1][j][k] / 9 +  input_image->image_pixels[i+1][j+1][k] / 9);
+                        
+                    }
+                    else if(i == height - 1 && j == 0) { // i+1 and j-1 does not exist
+                        smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i-1][j][k] / 9 +  input_image->image_pixels[i-1][j+1][k] / 9+  input_image->image_pixels[i][j][k] / 9+  input_image->image_pixels[i][j+1][k] / 9);
+                    }
+                    
+                    else if(i == 0 && j == width - 1) { // i-1 and j+1 does not exist
+                        smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i][j-1][k] / 9 +  input_image->image_pixels[i][j][k] / 9+   input_image->image_pixels[i+1][j-1][k] / 9 +  input_image->image_pixels[i+1][j][k] / 9);
+                    }
+                    else if(i == height - 1 && j == width - 1) { // i+1 and j+1 does not exist
+                        smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i-1][j-1][k] / 9 +  input_image->image_pixels[i-1][j][k] / 9 +  input_image->image_pixels[i][j-1][k] / 9 +  input_image->image_pixels[i][j][k] / 9);
+                    }
+                    else if (i == 0) {  // i - 1 does not exist
+                            smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i][j-1][k] / 9 +  input_image->image_pixels[i][j][k] / 9+  input_image->image_pixels[i][j+1][k] / 9+  input_image->image_pixels[i+1][j-1][k] / 9+  input_image->image_pixels[i+1][j][k] / 9+  input_image->image_pixels[i+1][j+1][k] / 9);
+                        }
+                    
+                    else if(j == 0) { // j -1 does not exist
+                        smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i-1][j][k] / 9+  input_image->image_pixels[i-1][j+1][k]  / 9+  input_image->image_pixels[i][j][k] / 9+  input_image->image_pixels[i][j+1][k] / 9+   input_image->image_pixels[i+1][j][k] / 9+  input_image->image_pixels[i+1][j+1][k]/ 9);
+                    }
+                    
+                    else if(i == height - 1) { // i+1 does not exist
+                        smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i-1][j-1][k] / 9+  input_image->image_pixels[i-1][j][k] / 9+  input_image->image_pixels[i-1][j+1][k] / 9+  input_image->image_pixels[i][j-1][k] / 9+  input_image->image_pixels[i][j][k] / 9+  input_image->image_pixels[i][j+1][k]/ 9);
+                    }		
+                    else if(j == width - 1) { // j + 1 does not exist
+                        smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i-1][j-1][k] / 9+  input_image->image_pixels[i-1][j][k] / 9+  input_image->image_pixels[i][j-1][k] / 9+  input_image->image_pixels[i][j][k]/ 9 +   input_image->image_pixels[i+1][j-1][k] / 9+  input_image->image_pixels[i+1][j][k] / 9);
+                    }	
+                    else {
+                    smoother->image_pixels[i][j][k] = ( input_image->image_pixels[i-1][j-1][k] / 9 +  input_image->image_pixels[i-1][j][k] / 9 +  input_image->image_pixels[i-1][j+1][k]/9 +  input_image->image_pixels[i][j-1][k]/9 +  input_image->image_pixels[i][j][k] / 9 +  input_image->image_pixels[i][j+1][k] / 9 +  input_image->image_pixels[i+1][j-1][k] / 9 +  input_image->image_pixels[i+1][j][k] / 9 +  input_image->image_pixels[i+1][j+1][k] / 9);
+                    
+                    }
+                }
+            }
+        }
+        __sync_lock_release(&lock2);	
+        __sync_lock_release(&lock1);	
+        
+    }
+	return nullptr;
+}
+
+// atomic_flag lock_stream2 = ATOMIC_FLAG_INIT; // initial lock set
+
+void* S2_find_details(void *thread_number)
+{
+
+    int my_number = *(int *)thread_number;
+	int width = input_image->width;
+	int height = input_image->height;
+	for(pt1 = 0; pt1 <= 1000; ++pt1) {
+        while(__sync_lock_test_and_set(&lock2,1));
+        while(__sync_lock_test_and_set(&lock1,1));
+        while(__sync_lock_test_and_set(&lock3,1));
+        // while(lock_stream1.test_and_set());
+        // while(lock_stream2.test_and_set());
+        printf("thread number : %d\tindex : %d\n", my_number, pt1);
+        for(int i = 1; i < height-1; i++)
+        {
+            for(int j = 1; j < width-1; j++)
+            {
+                for(int k = 0; k < 3; k++)
+                {
+                    details->image_pixels[i][j][k] = max(0, (input_image->image_pixels[i][j][k] - smoother->image_pixels[i][j][k]));
+                }
+            }
+        }
+        __sync_lock_release(&lock1);	
+        __sync_lock_release(&lock4);	
+        __sync_lock_release(&lock3);
+
+        if(pt >= 1000)
+        {
+            __sync_lock_release(&lock2);
+        }	
+
+
+    }
+
+	return nullptr;
+}
+
+void* S3_sharpen(void* thread_number)
+{
+	int my_number = *(int *)thread_number;
+	int width = input_image->width;
+	int height = input_image->height;
+    for(int pt2 = 1; pt2 <= 1000; ++pt2) {
+        // while(lock_stream2.test_and_set());
+        while (__sync_lock_test_and_set(&lock4, 1));
+        while (__sync_lock_test_and_set(&lock3, 1));
+
+        printf("thread number : %d\tindex : %d\n", my_number, pt2);
+        for(int i = 1; i < height-1; i++)
+        {
+            for(int j = 1; j < width-1; j++)
+            {
+                for(int k = 0; k < 3; k++)
+                {
+                    sharp->image_pixels[i][j][k] = min(255, input_image->image_pixels[i][j][k] + details->image_pixels[i][j][k]) * a;
+                }
+            }
+        }
+        __sync_lock_release(&lock3);
+
+        if(pt1 >= 1000)
+        {
+            __sync_lock_release(&lock4);
+        }
+    }
+
+	return nullptr; 
+}
+
+
+int main(int argc, char *argv[]) {
+
+	pthread_t thread1, thread2, thread3;
+	int  iret1, iret2, iret3;
+	int thread_number1 = 1, thread_number2 = 2, thread_number3 = 3;
+
+    input_image = read_ppm_file(argv[1]);
+
+    smoother = new struct image_t;
+    details = new struct image_t;
+    sharp = new struct image_t;
+
+    int width = input_image->width;
+	int height = input_image->height;
+
+    // memory allocation for global smoothened image ------------ threads share same global variable
+    smoother->height = height;
+	smoother->width = width;
+	smoother->image_pixels = new uint8_t**[height];
+	for(int i = 0; i < height; i++)
+	{
+		smoother->image_pixels[i] = new uint8_t*[width];
+		for(int j = 0; j < width; j++)
+			smoother->image_pixels[i][j] = new uint8_t[3];
+	}
+
+    // memory allocation for global detailed image
+    details->height = height;
+	details->width = width;
+	details->image_pixels = new uint8_t**[height];
+	
+	for(int i = 0; i < height; i++)
+	{
+		details->image_pixels[i] = new uint8_t*[width];
+		for(int j = 0; j < width; j++)
+			details->image_pixels[i][j] = new uint8_t[3];
+	}
+
+    // memory allocation for global sharper image
+	sharp->height = height;
+	sharp->width = width;
+	sharp->image_pixels = new uint8_t**[height];
+	
+	for(int i = 0; i < height; i++)
+	{
+		sharp->image_pixels[i] = new uint8_t*[width];
+		for(int j = 0; j < width; j++)
+			sharp->image_pixels[i][j] = new uint8_t[3];
+	}
+
+
+	/* Create independent threads each of which will execute function */
+	iret1 = pthread_create(&thread1, NULL, S1_smoothen, &thread_number1);
+	if(iret1)
+	{
+		fprintf(stderr,"Error - pthread_create() return code: %d\n",iret1);
+		exit(EXIT_FAILURE);
+	}
+	iret2 = pthread_create(&thread2, NULL, S2_find_details, &thread_number2);
+	if(iret2)
+	{
+		fprintf(stderr,"Error - pthread_create() return code: %d\n",iret2);
+		exit(EXIT_FAILURE);
+	}
+    iret3 = pthread_create(&thread3, NULL, S3_sharpen, &thread_number3);
+	if(iret3)
+	{
+		fprintf(stderr,"Error - pthread_create() return code: %d\n",iret3);
+		exit(EXIT_FAILURE);
+	}
+
+	pthread_join(thread1, NULL);
+	pthread_join(thread2, NULL);
+	pthread_join(thread3, NULL);
+
+	// printf("\nsum = %d\n", sum);
+    printf("ttis");
+	exit(EXIT_SUCCESS);
+    return 1;
+}