diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..6a73ec0
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,9 @@
+{
+    "files.associations": {
+        "voronoi.h": "c",
+        "stdio.h": "c",
+        "dcel.h": "c",
+        "common.h": "c",
+        "string.h": "c"
+    }
+}
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 32c22e8..3b7b5e2 100755
--- a/Makefile
+++ b/Makefile
@@ -1,2 +1,15 @@
-voronoi1 : voronoi.c
-	gcc -Wall -Wextra -Werror -pedantic -g -o voronoi1 voronoi.c
+voronoi1: main
+	gcc -Wall -Wextra -Werror -pedantic -g -o voronoi1 main.o voronoi.o dcel.o common.o
+	rm *.o
+
+main: voronoi
+	gcc -Wall -Wextra -Werror -pedantic -g -o main.o main.c -c
+
+voronoi: dcel
+	gcc -Wall -Wextra -Werror -pedantic -g -o voronoi.o voronoi.c -c
+
+dcel: common
+	gcc -Wall -Wextra -Werror -pedantic -g -o dcel.o dcel.c -c
+
+common:
+	gcc -Wall -Wextra -Werror -pedantic -g -o common.o common.c -c
diff --git a/common.c b/common.c
new file mode 100644
index 0000000..a324131
--- /dev/null
+++ b/common.c
@@ -0,0 +1,53 @@
+/* common.c
+ *
+ * Created by Rory Healy (healyr@student.unimelb.edu.au)
+ * Created on 25th August 2021
+ * Last modified 25th August 2021
+ *
+ * Contains functions for general use throughout other files.
+ *
+ */
+
+#ifndef COMMON_HEADER
+#include "common.h"
+#endif
+
+#define ARGC_CORRECT_LEN 4
+#define MEMORY_ALLOCATION_ERROR "Error: Cannot allocate memory.\n"
+#define OPEN_FILE_ERROR "Error: Unable to open file %s\n"
+#define NUM_FILE_ERROR "Error: Incorrect number of inputs (3 required).\n"
+
+/* Checks if a given pointer is null. Used for malloc() and realloc(). */
+void checkNullPointer(void *ptr) {
+	if (!ptr) {
+		fputs(MEMORY_ALLOCATION_ERROR, stderr);
+		exit(EXIT_FAILURE);
+	}
+}
+
+/* Checks the validity of the command line input arguments */
+void checkInputArgs(int argc, char **argv, FILE **datasetFile, \
+    FILE **polygonFile, FILE **outputFile) {
+    if (argc != ARGC_CORRECT_LEN) {
+        fputs(NUM_FILE_ERROR, stderr);
+        exit(EXIT_FAILURE);
+    }
+
+    *datasetFile = fopen(argv[1], "r");
+    if (*datasetFile == NULL) {
+        fprintf(stderr, OPEN_FILE_ERROR, argv[1]);
+        exit(EXIT_FAILURE);
+    }
+    
+    *polygonFile = fopen(argv[2], "r");
+    if (*polygonFile == NULL) {
+        fprintf(stderr, OPEN_FILE_ERROR, argv[2]);
+        exit(EXIT_FAILURE);
+    }
+
+    *outputFile = fopen(argv[3], "w");
+    if (*outputFile == NULL) {
+        fprintf(stderr, OPEN_FILE_ERROR, argv[3]);
+        exit(EXIT_FAILURE);
+    }
+}
diff --git a/common.h b/common.h
new file mode 100644
index 0000000..3ac77a7
--- /dev/null
+++ b/common.h
@@ -0,0 +1,23 @@
+#ifndef STDIO_HEADER
+
+#define STDIO_HEADER
+#include <stdio.h>
+
+#endif
+
+#ifndef STDLIB_HEADER
+
+#define STDLIB_HEADER
+#include <stdlib.h>
+
+#endif
+
+#ifndef COMMON_HEADER
+
+#define COMMON_HEADER
+
+void checkNullPointer(void *ptr);
+void checkInputArgs(int argc, char **argv, FILE **datasetFile, \
+    FILE **polygonFile, FILE **outputFile);
+
+#endif
diff --git a/dcel.c b/dcel.c
new file mode 100644
index 0000000..a2ab3be
--- /dev/null
+++ b/dcel.c
@@ -0,0 +1,68 @@
+/* dcel.c
+ *
+ * Created by Rory Healy (healyr@student.unimelb.edu.au)
+ * Created on 25th August 2021
+ * Last modified 25th August 2021
+ *
+ * Contains functions for the DCEL data structure, including creating, 
+ * splitting an edge, and identifying towers in faces.
+ *
+ */
+
+#ifndef DCEL_HEADER
+#include "dcel.h"
+#endif
+
+#ifndef COMMON_HEADER
+#include "common.h"
+#endif
+
+struct halfEdge {
+    halfEdge_t *previous;
+    halfEdge_t *next;
+    halfEdge_t *twin;
+    int face;
+    int edge;
+};
+
+struct vertex {
+    double x;
+    double y;
+};
+
+struct edge {
+    halfEdge_t halfEdge;
+};
+
+struct face {
+    halfEdge_t start;
+};
+
+/* Reads the polygon file and stores the information in the vertices array. */
+vertex_t **readPolygon(vertex_t **vertices, FILE *polygonFile, int *numVertices) {
+    double currentX, currentY;
+    int maxSizeVertices = 1;
+    while ((fscanf(polygonFile, "%lf %lf", &currentX, &currentY)) != EOF) {
+        /* Check if there enough space in the towers array */
+        if (*numVertices == maxSizeVertices) {
+            maxSizeVertices *= 2;
+            vertex_t **temp = realloc(vertices, maxSizeVertices * sizeof(*vertices));
+            checkNullPointer(temp);
+            vertices = temp;
+        }
+
+        /* The current vertex being filled in with information */
+        vertices[*numVertices] = malloc(sizeof(*vertices[*numVertices]));
+        vertices[*numVertices]->x = currentX;
+        vertices[*numVertices]->y = currentY;
+        *numVertices += 1;
+    }
+    return vertices;
+}
+
+void freeVertices(vertex_t **vertices, int numVertices) {
+    for (int i = 0; i < numVertices; i++) {
+        free(vertices[i]);
+    }
+    free(vertices);
+}
diff --git a/dcel.h b/dcel.h
new file mode 100644
index 0000000..5066490
--- /dev/null
+++ b/dcel.h
@@ -0,0 +1,20 @@
+#ifndef STDIO_HEADER
+
+#define STDIO_HEADER
+#include <stdio.h>
+
+#endif
+
+#ifndef DCEL_HEADER
+
+#define DCEL_HEADER
+
+typedef struct halfEdge halfEdge_t;
+typedef struct vertex vertex_t;
+typedef struct edge edge_t;
+typedef struct face face_t;
+
+vertex_t **readPolygon(vertex_t **vertices, FILE *polygonFile, \
+    int *numVertices);
+void freeVertices(vertex_t **vertices, int numVertices);
+#endif
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..79de3ab
--- /dev/null
+++ b/main.c
@@ -0,0 +1,64 @@
+/* main.c
+ *
+ * Created by Rory Healy (healyr@student.unimelb.edu.au)
+ * Created on 25th August 2021
+ *  Last modified 25th August 2021
+ *
+ * Lists the watchtowers that are in each face of the polygon.
+ * The polygon can be split using a pair of integers, which represent
+ * the edge numbers that should be connected. This comes from stdin.
+ *
+ * To run the program type: 
+ * ./voronoi1 dataset_file polygon_file output_file < splits
+ * 
+ * Options:
+ *   dataset_file    required    Path to the dataset file (CSV)
+ *   polygon_file    required    Path to the polygon file (txt)
+ *   output_file     required    Output solution file
+ *   splits          optional    Pairs of integers to split the edges
+ *
+ */
+
+#ifndef DCEL_HEADER
+#include "dcel.h"
+#endif
+
+#ifndef COMMON_HEADER
+#include "common.h"
+#endif
+
+#ifndef VORONOI_HEADER
+#include "voronoi.h"
+#endif
+
+int main(int argc, char **argv) {
+    /* Input and output files */
+    FILE *datasetFile = NULL, *polygonFile = NULL, *outputFile = NULL;
+    checkInputArgs(argc, argv, &datasetFile, &polygonFile, &outputFile);
+
+    /* Stores information about the towers given in dataset file */
+    tower_t **towers = malloc(sizeof(*towers));
+    checkNullPointer(towers);
+    int numTowers = 0;
+    towers = readTowers(towers, datasetFile, &numTowers);
+
+    /* Stores information about the vertices in the polygon file */
+    vertex_t **vertices = malloc(sizeof(*vertices));
+    checkNullPointer(vertices);
+    int numVertices = 0;
+    vertices = readPolygon(vertices, polygonFile, &numVertices);
+
+    /* Create DCEL structure from vertices */
+
+    /* Check for splits, split the polygon if needed */
+    
+    /* Counts towers in each polygon, outputs to outputFile */
+
+    /* Cleaning up data */
+    freeTowers(towers, numTowers);
+    freeVertices(vertices, numVertices);
+    fclose(datasetFile);
+    fclose(polygonFile);
+    fclose(outputFile);
+    return 0;
+}
diff --git a/voronoi.c b/voronoi.c
index c76b593..0d02e27 100755
--- a/voronoi.c
+++ b/voronoi.c
@@ -1,165 +1,122 @@
 /* voronoi.c
-*
-* Created by Rory Healy (healyr@student.unimelb.edu.au)
-* 12th August 2021
-* 
-*/
-
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-#include "voronoi.h"
-
-#define OPEN_FILE_ERROR "Error: Unable to open file %s\n"
-#define NUM_FILE_ERROR "Error: Incorrect number of inputs (3 required).\n"
-#define MEMORY_ALLOCATION_ERROR "Error: Cannot allocate memory.\n"
-
-#define ARGC_CORRECT_LEN 4
-#define NUM_CSV_FIELDS 6
-#define MAX_FIELD_LEN 128
-#define MAX_CSV_ENTRY_LEN 512
-
-int main(int argc, char **argv) {
-    // /* Input and output files */
-    FILE *dataset = NULL, *polygonData = NULL, *output = NULL;
-    checkInputArgs(argc, argv, &dataset, &polygonData, &output);
-
-    /* Stores information about the watchtowers given in dataset file */
-    watchtower_t **watchtowers = malloc(sizeof(*watchtowers));
-    checkNullPointer(watchtowers);
-    int numWatchtowers = 0;
-    watchtowers = readWatchtowers(watchtowers, dataset, &numWatchtowers);
-
-    /* Cleaning up data */
-    for (int i = 0; i < numWatchtowers; i++) {
-        free(watchtowers[i]->id);
-        free(watchtowers[i]->manager);
-        free(watchtowers[i]->postcode);
-        free(watchtowers[i]);
-    }
-    
-    free(watchtowers);
-    fclose(dataset);
-    fclose(polygonData);
-    fclose(output);
-    return 0;
-}
-
-/* Checks the validity of the command line input arguments */
-void checkInputArgs(int argc, char **argv, FILE **datasetFile, \
-    FILE **polygonFile, FILE **outputFile) {
-    if (argc != ARGC_CORRECT_LEN) {
-        fputs(NUM_FILE_ERROR, stderr);
-        exit(EXIT_FAILURE);
-    }
-
-    *datasetFile = fopen(argv[1], "r");
-    if (*datasetFile == NULL) {
-        fprintf(stderr, OPEN_FILE_ERROR, argv[1]);
-        exit(EXIT_FAILURE);
-    }
-    
-    *polygonFile = fopen(argv[2], "r");
-    if (*polygonFile == NULL) {
-        fprintf(stderr, OPEN_FILE_ERROR, argv[2]);
-        exit(EXIT_FAILURE);
-    }
-
-    *outputFile = fopen(argv[3], "w");
-    if (*outputFile == NULL) {
-        fprintf(stderr, OPEN_FILE_ERROR, argv[3]);
-        exit(EXIT_FAILURE);
-    }
-}
-
-/* Reads the CSV file and stores the information in the watchtowers array.
- * Returns the number of watchtowers read.
+ *
+ * Created by Rory Healy (healyr@student.unimelb.edu.au)
+ * Created on 12th August 2021
+ * Last modified 25th August 2021
+ *
+ * Contains functions involving the reading of the dataset CSV file.
+ *
  */
-watchtower_t** readWatchtowers(watchtower_t **watchtowers, FILE* datasetFile, \
-    int *numWatchtowers) {
+
+#ifndef COMMON_HEADER
+#include "common.h"
+#endif
+
+#ifndef VORONOI_HEADER
+#include "voronoi.h"
+#endif
+
+#include <string.h>
+
+#define BASE_10 10
+#define MAX_CSV_ENTRY_LEN 512
+#define MAX_FIELD_LEN 128
+#define NUM_CSV_FIELDS 6
+
+struct tower {
+    char *id;
+    char *postcode;
+    char *manager;
+    int population;
+    double x;
+    double y;
+};
+
+/* Reads the CSV file and stores the information in the towers array. */
+tower_t **readTowers(tower_t **towers, FILE* datasetFile, int *numTowers) {
     /* Maximum length of a single CSV line */
     size_t lineBufferSize = MAX_CSV_ENTRY_LEN + 1;
 
     /* Stores the current line from the CSV */
-    char *lineBuffer = (char *) malloc(lineBufferSize * sizeof(char));
+    char *lineBuffer = malloc(lineBufferSize * sizeof(char));
     checkNullPointer(lineBuffer);
 
-    int maxSizeWatchtowers = 1;
+    int maxSizetowers = 1;
 
     /* Discard the header line, then read the rest of the CSV */
     getline(&lineBuffer, &lineBufferSize, datasetFile);
     while (getline(&lineBuffer, &lineBufferSize, datasetFile) > 0) {
-        /* Check if there enough space in the watchtowers array */
-        if (*numWatchtowers == maxSizeWatchtowers) {
-            maxSizeWatchtowers *= 2;
-            watchtower_t **temp = realloc(watchtowers, \
-                maxSizeWatchtowers * sizeof(*watchtowers));
+        /* Check if there enough space in the towers array */
+        if (*numTowers == maxSizetowers) {
+            maxSizetowers *= 2;
+            tower_t **temp = realloc(towers, maxSizetowers * sizeof(*towers));
             checkNullPointer(temp);
-            watchtowers = temp;
+            towers = temp;
         }
 
         /* The current tower being filled in with information */
-        watchtowers[*numWatchtowers] = malloc(sizeof(*watchtowers[*numWatchtowers]));
+        towers[*numTowers] = malloc(sizeof(*towers[*numTowers]));
 
-        /* Stores the current CSV field for the current line */
-        char *token = strtok(lineBuffer, ",");
-        size_t tokenLength;
-
-        /* Read the line in to currTower */
-        for (int i = 0; i < NUM_CSV_FIELDS; i++) {
-            tokenLength = strlen(token);
-            switch(i) {
-                /* Case 0, 1, and 3 deal with strings in the CSV
-                 * Case 2 deals with an integer
-                 * Case 4 and 5 deal with doubles
-                 * Each case is handled seperately to fill in the
-                 * watchtower with no space wasted.
-                 */
-                case 0:
-                    watchtowers[*numWatchtowers]->id = (char *) malloc( \
-                        sizeof(char) * tokenLength + 1);
-                    checkNullPointer(watchtowers[*numWatchtowers]->id);
-                    strcpy(watchtowers[*numWatchtowers]->id, token);
-                    watchtowers[*numWatchtowers]->id[tokenLength] = '\0';
-                    break;
-                case 1:
-                    watchtowers[*numWatchtowers]->postcode = (char *) malloc( \
-                        sizeof(char) * tokenLength + 1);
-                    checkNullPointer(watchtowers[*numWatchtowers]->postcode);
-                    strcpy(watchtowers[*numWatchtowers]->postcode, token);
-                    watchtowers[*numWatchtowers]->postcode[tokenLength] = '\0';
-                    break;
-                case 3:
-                    watchtowers[*numWatchtowers]->manager = (char *) malloc( \
-                        sizeof(char) * tokenLength + 1);
-                    checkNullPointer(watchtowers[*numWatchtowers]->manager);
-                    strcpy(watchtowers[*numWatchtowers]->manager, token);
-                    watchtowers[*numWatchtowers]->manager[tokenLength] = '\0';
-                    break;
-                case 2:
-                    watchtowers[*numWatchtowers]->population = \
-                        strtol(token, NULL, 10);
-                    break;
-                case 4:
-                    watchtowers[*numWatchtowers]->x = strtod(token, NULL);
-                    break;
-                case 5:
-                    watchtowers[*numWatchtowers]->y = strtod(token, NULL);
-                    break;
-            }
-            token = strtok(NULL, ",");
-        }
-
-        *numWatchtowers += 1;    
+        readCurrentLine(lineBuffer, towers[*numTowers]);
+        *numTowers += 1;    
     }
-
     free(lineBuffer);
-    return watchtowers;
+    return towers;
 }
 
-void checkNullPointer(void *ptr) {
-	if (!ptr) {
-		fputs(MEMORY_ALLOCATION_ERROR, stderr);
-		exit(EXIT_FAILURE);
-	}
+/* Takes a line from the CSV and converts the data into a tower_t format */
+void readCurrentLine(char* lineBuffer, tower_t* tower) {
+    /* Stores the current CSV field for the current line */
+    char *token = strtok(lineBuffer, ",");
+    size_t tokenLength;
+
+    for (int i = 0; i < NUM_CSV_FIELDS; i++) {
+        tokenLength = strlen(token);
+        switch(i) {
+            /* Case 0, 1, and 3 deal with strings
+             * Case 2 deals with an integer
+             * Case 4 and 5 deal with doubles
+             * Each case is handled seperately to fill in the
+             * tower with no space wasted.
+             */
+            case 0:
+                tower->id = malloc(sizeof(char) * tokenLength + 1);
+                checkNullPointer(tower->id);
+                strcpy(tower->id, token);
+                tower->id[tokenLength] = '\0';
+                break;
+            case 1:
+                tower->postcode = malloc(sizeof(char) * tokenLength + 1);
+                checkNullPointer(tower->postcode);
+                strcpy(tower->postcode, token);
+                tower->postcode[tokenLength] = '\0';
+                break;
+            case 2:
+                tower->population = strtol(token, NULL, BASE_10);
+                break;
+            case 3:
+                tower->manager = malloc(sizeof(char) * tokenLength + 1);
+                checkNullPointer(tower->manager);
+                strcpy(tower->manager, token);
+                tower->manager[tokenLength] = '\0';
+                break;
+            case 4:
+                tower->x = strtod(token, NULL);
+                break;
+            case 5:
+                tower->y = strtod(token, NULL);
+                break;
+        }
+        token = strtok(NULL, ",");
+    }
+}
+
+void freeTowers(tower_t **towers, int numTowers) {
+    for (int i = 0; i < numTowers; i++) {
+        free(towers[i]->id);
+        free(towers[i]->manager);
+        free(towers[i]->postcode);
+        free(towers[i]);
+    }
+    free(towers);
 }
diff --git a/voronoi.h b/voronoi.h
index cb34dcd..10113b1 100755
--- a/voronoi.h
+++ b/voronoi.h
@@ -1,14 +1,25 @@
-typedef struct Watchtower {
-    char *id;
-    char *postcode;
-    char *manager;
-    int population;
-    double x;
-    double y;
-} watchtower_t;
+#ifndef STDIO_HEADER
 
-void checkInputArgs(int argc, char **argv, FILE **datasetFile, \
-    FILE **polygonFile, FILE **outputFile);
-watchtower_t** readWatchtowers(watchtower_t **watchtowers, FILE* datasetFile, \
-    int *numWatchtowers);
-void checkNullPointer(void *ptr);
+#define STDIO_HEADER
+#include <stdio.h>
+
+#endif
+
+#ifndef STDLIB_HEADER
+
+#define STDLIB_HEADER
+#include <stdlib.h>
+
+#endif
+
+#ifndef VORONOI_HEADER
+
+#define VORONOI_HEADER
+
+typedef struct tower tower_t;
+
+tower_t** readTowers(tower_t **towers, FILE* datasetFile, int *numTowers);
+void readCurrentLine(char* lineBuffer, tower_t* tower);
+void freeTowers(tower_t **towers, int numTowers);
+
+#endif
diff --git a/voronoi1 b/voronoi1
index 41afb53..0c4f7ae 100755
Binary files a/voronoi1 and b/voronoi1 differ