feat: working wf

labs/cs2106/labs/lab4/linkedlist/llist.c

@@ -0,0 +1,239 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "llist.h"
+
+//#define DEBUG       // Enable debug printing
+
+// Debug printer
+
+void dbprintf(char *format, ...) {
+#ifdef DEBUG
+    va_list args;
+
+    va_start(args, format);
+    vprintf(format, args);
+#endif
+}
+
+// Implements a double linked list.
+
+// Create a new node. You need to
+// Create your own TData node, populate
+// it, then create a new node with a suitable
+// key. Insertion into the link list is
+// by ascending order of the key. An example key
+// might be the starting address of a memory segment.
+
+TNode *make_node(unsigned int key, TData *data) {
+    TNode *node = malloc(sizeof(TNode));
+    node->key = key;
+    node->pdata = data;
+    node->prev = NULL;
+    node->next = NULL;
+
+    return node;
+}
+
+// Inserts a node into the correct point of the
+// double linked list. The list is sorted
+// in ascending order of the key. Duplicate keys
+// are permitted, though not recommended.
+// llist = Pointer to link list
+// node = Pointer to node created by make_node
+// dir = 0: Insert in ascending order
+// dir = 1: Insert in descending order
+
+void insert_node(TNode **llist, TNode *node, int dir) {
+    if(*llist == NULL) {
+        *llist = node;
+        (*llist)->trav = *llist;
+        (*llist)->tail = *llist;
+    }
+    else 
+        if(((*llist)->key >= node->key && dir == 0) || (((*llist)->key <= node->key) && dir == 1)) {
+            node->next = *llist;
+            (*llist)->prev = node;
+            *llist = node;
+            (*llist)->trav = *llist;
+        }
+        else
+        {
+            TNode *trav = *llist;
+
+            if(dir == 0)
+                while(trav->next != NULL && trav->key < node->key) 
+                    trav = trav->next;
+            else if(dir == 1)
+                while(trav->next != NULL && trav->key > node->key)
+                    trav = trav->next;
+
+            if(trav->next == NULL && ((trav->key < node->key && dir == 0) || 
+                        (trav->key > node->key && dir == 1))) {
+                trav->next = node;
+                node->prev = trav;
+
+                // Set the tail
+                (*llist)->tail = node;
+            } else {
+                // Insert into the previous space
+
+                node->next = trav;
+
+                if(trav->prev != NULL) {
+                    trav->prev->next = node;
+                    node->prev = trav->prev;
+                }
+
+                if(trav->next != NULL) {
+                }
+
+                trav->prev = node;
+            }
+        }
+}
+
+// Remove a given node from the linked list
+void delete_node(TNode **llist, TNode *node) {
+
+    if(*llist == NULL || node == NULL)
+        return;
+
+    if((*llist)->key == node->key) {
+        // Node to be deleted is at the front of the list.
+        *llist = (*llist)->next;
+
+        // Ensure that we don't point to it anymore.
+        if(*llist != NULL)
+            (*llist)->prev = NULL;
+    }
+    else
+    {
+        TNode *trav = *llist;
+
+        while(trav != NULL && trav->key != node->key) 
+            trav = trav->next;
+
+        // We've found the deletion point
+        if(trav != NULL) {
+            trav->prev->next = trav->next;
+
+            if(trav->next != NULL) 
+                trav->next->prev = trav->prev;
+            else
+                (*llist)->tail = trav->prev;
+        }
+
+    }
+
+    free(node);
+}
+
+// Find a node that has the value of key
+// If there are duplicate keys, the first one encountered
+// will be returned.
+TNode *find_node(TNode *llist, unsigned int key) {
+    if(llist == NULL)
+        return NULL;
+
+    TNode *trav = llist;
+
+    while(trav != NULL && trav->key != key)
+        trav = trav->next;
+
+    return trav;
+}
+
+// Merge the node provided with either the node after or the node before.
+// You need to manage merging the data in node->pdata yourself. This code just
+// deletes the larger of the two nodes.
+// dir = 0: Merge with node before
+// dir = 1: Merge with node after
+
+void merge_node(TNode *llist, TNode *node, int dir) {
+    if(dir == 0) {
+        if(node->prev == NULL)
+            return;
+
+        delete_node(&llist, node);
+    }
+    else 
+        if(dir == 1) {
+            if(node->next == NULL)
+                return;
+
+            delete_node(&llist, node->next);
+        }
+}
+
+// Go over every element of llist, and call func
+// func prototype is void func(TNode *);
+
+void process_list(TNode *llist, void (*func)(TNode *)) {
+    TNode *trav = llist;
+    while(trav) {
+        func(trav);
+        trav = trav->next;
+    }
+
+}
+
+
+// Purge the entire list. You must
+// free any dynamic data in the TData
+// struct yourself.
+void purge_list(TNode **llist) {
+    TNode *trav = *llist, *tmp;
+    while(trav) {
+        tmp = trav->next;
+        free(trav);
+        trav = tmp;
+    }
+
+    *llist = NULL;
+}
+
+
+// Reset traverser
+// where=0 START: Resets traverser to start of list
+// where=1 END: Rsets
+void reset_traverser(TNode *llist, int where)
+{
+    if(llist == NULL)
+        return;
+
+    if(where == FRONT)
+        llist->trav = llist;
+    else
+        if(where == REAR)
+            llist->trav = llist->tail;
+}
+
+// Get the next node
+TNode *succ(TNode *llist)
+{
+    if(llist == NULL)
+        return NULL;
+
+    TNode *ret = llist->trav;
+
+    if(llist->trav != NULL)
+        llist->trav = llist->trav->next;
+
+    return ret;
+}
+
+// Get the previous node
+TNode *pred(TNode *llist)
+{
+    if(llist == NULL)
+        return NULL;
+
+    TNode *ret = llist->trav;
+
+    if(llist->trav != NULL)
+        llist->trav = llist->trav->prev;
+
+    return ret;
+}

labs/cs2106/labs/lab4/linkedlist/llist.h

@@ -0,0 +1,114 @@
+
+// Uncomment the next line to enable debug printing
+#define DEBUG       // Enable debug printing
+
+// The debug printer; used like a normal printf, except
+// that printing can be turned off by commenting out the
+// #define DEBUG above.
+void dbprintf(char *format, ...);
+
+// You should modify this structure to hold
+// whatever you need to implement your
+// memory manager. You can delete the
+// val field. It is only used for testlist.c
+
+typedef struct td {
+    int val;
+} TData;
+
+
+/* ----------------------------------------- 
+   BASIC ROUTINES
+
+   Basic linked list routines
+
+   ---------------------------------------- */
+
+// Basic double linked list node. 
+
+typedef struct tn {
+    unsigned int key;
+    TData *pdata; // Pointer to the data you want to store
+
+    struct tn *trav; // Only used in the root for traversal
+    struct tn *tail; // Only used in the root for finding the end of the list
+    struct tn *prev;
+    struct tn *next;
+} TNode;
+
+// Insert Direction
+#define ASCENDING   0
+#define DESCENDING  1
+
+// Merge direction
+#define PRECEDING   0
+#define SUCCEEDING  1
+
+// Traverser position
+#define FRONT       0
+#define REAR        1
+
+// Create a new node. You need to
+// Create your own TData node, populate
+// it, then create a new node with a suitable
+// key. Insertion into the link list is
+// by ascending order of the key. An example key
+// might be the starting address of a memory segment.
+
+TNode *make_node(unsigned int key, TData *data);
+
+// Inserts a node into the correct point of the
+// double linked list. The list is sorted
+// in ascending order of the key. Duplicate keys
+// are permitted, though not recommended.
+// llist = Pointer to link list
+// node = Pointer to node created by make_node
+// dir = 0: Insert in ascending order
+// dir = 1: Insert in descending order
+
+void insert_node(TNode **llist, TNode *node, int dir);
+
+
+// Remove a given node from the linked list
+void delete_node(TNode **llist, TNode *node);
+
+// Find a node that has the value of key
+// If there are duplicate keys, the first one encountered
+// will be returned.
+TNode *find_node(TNode *llist, unsigned int key);
+
+// Merge the node provided with either the node after or the node before.
+// You need to manage merging the data in node->pdata yourself. This code just
+// deletes the larger of the two nodes.
+// dir = 0: Merge with node before
+// dir = 1: Merge with node after
+
+void merge_node(TNode *llist, TNode *node, int dir);
+
+// Purge the entire list. You must
+// free any dynamic data in the TData
+// struct yourself.
+void purge_list(TNode **llist);
+
+/* ----------------------------------------- 
+   TRAVERSAL ROUTINES
+
+   Lets you traverse the linked list
+
+   ---------------------------------------- */
+
+// Go over every element of llist, and call func
+// func prototype is void func(TNode *);
+
+void process_list(TNode *llist, void (*func)(TNode *));
+
+// Reset traverser
+// where=0 START: Resets traverser to start of list
+// where=1 END: Rsets
+void reset_traverser(TNode *llist, int where);
+
+// Get the next node
+TNode *succ(TNode *llist);
+
+// Get the previous node
+TNode *pred(TNode *llist);

labs/cs2106/labs/lab4/linkedlist/mymalloc.c

@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "mymalloc.h"
+
+char _heap[MEMSIZE] = {0};
+TNode *_memlist = NULL; // To maintain information about length
+
+// Do not change this. Used by the test harness.
+// You may however use this function in your code if necessary.
+long get_index(void *ptr) {
+    if(ptr == NULL)
+        return -1;
+    else
+        return (long) ((char *) ptr - &_heap[0]);
+}
+
+// Allocates size bytes of memory and returns a pointer
+// to the first byte.
+void *mymalloc(size_t size) {
+}
+
+// Frees memory pointer to by ptr.
+void myfree(void *ptr) {
+}
+

labs/cs2106/labs/lab4/linkedlist/mymalloc.h

@@ -0,0 +1,5 @@
+#define MEMSIZE 64 * 1024        // Size of memory in bytes
+
+long get_index(void *ptr);
+void *mymalloc(size_t);
+void myfree(void *);

labs/cs2106/labs/lab4/linkedlist/testlist.c

@@ -0,0 +1,178 @@
+#include <stdio.h>
+#include <assert.h>
+#include <stdlib.h>
+#include "llist.h"
+
+#define COUNT   10
+
+void print_node(TNode *node) {
+    if(node != NULL)
+        printf("Key: %d\n", node->key);
+    else
+        printf("Unable to find key.\n");
+}
+
+void free_data(TNode *node) {
+    free(node->pdata);
+}
+
+void trav_list(TNode *llist) {
+    reset_traverser(llist, FRONT);
+    TNode *node;
+
+    do {
+        node = succ(llist);
+        if(node)
+            print_node(node);
+    } while(node != NULL);
+}
+
+void rev_trav_list(TNode *llist) {
+    reset_traverser(llist, REAR);
+    TNode *node;
+
+    do{
+        node = pred(llist);
+        if(node)
+            print_node(node);
+    } while(node != NULL);
+}
+
+
+int main(){
+    TNode *llist = NULL;
+
+    int test_array[COUNT] = {10, 6, 2, 8, 1, 4, 5, 3, 9, 7};
+
+    // Insert
+
+    char c;
+    printf("Hit enter to start ascending order test\n");
+    scanf("%c", &c);
+
+    int i;
+    printf("Inserting in ascending order\n");
+    TData *data;
+    TNode *node;
+
+    for(i=0; i<COUNT; i++) {
+        data = (TData *) malloc(sizeof(TData));
+        data->val = test_array[i];
+        node = make_node(test_array[i], data);
+        insert_node(&llist, node, ASCENDING);
+    }
+
+    printf("Printing entire list\n");
+    process_list(llist, print_node);
+    printf("\n");
+
+    printf("Printing entire list using reverse traversal\n");
+    rev_trav_list(llist);
+    printf("\n");
+
+    printf("Searching for 2\n");
+    node = find_node(llist, 2);
+    print_node(node);
+
+    printf("Deleting node 2\n");
+    delete_node(&llist, node);
+
+    printf("Searching for 2\n");
+    node = find_node(llist, 2);
+    print_node(node);
+    printf("\n");
+
+    printf("Searching for 5\n");
+    node = find_node(llist, 5);
+    print_node(node);
+
+    printf("Deleting node 5\n");
+    delete_node(&llist, node);
+
+    printf("Searching for 5\n");
+    node = find_node(llist, 5);
+    print_node(node);
+    printf("\n");
+
+    printf("Searching for 22\n");
+    node = find_node(llist, 22);
+    print_node(node);
+
+    printf("Deleting node 22\n");
+    delete_node(&llist, node);
+
+    printf("Searching for 22\n");
+    node = find_node(llist, 22);
+    print_node(node);
+    printf("\n");
+
+    printf("Purging list\n");
+    process_list(llist, free_data);
+    purge_list(&llist);
+
+    printf("Printing entire list\n");
+    process_list(llist, print_node);
+    printf("\n");
+
+    printf("Hit enter to start descending order test\n");
+    scanf("%c", &c);
+
+    printf("Inserting in descending order\n");
+    for(i=0; i<COUNT; i++) {
+        TNode *node = make_node(test_array[i], NULL);
+        insert_node(&llist, node, DESCENDING);
+    }
+
+    printf("Printing entire list\n");
+    process_list(llist, print_node);
+    printf("\n");
+
+    printf("Printing entire list using reverse traversal\n");
+    rev_trav_list(llist);
+    printf("\n");
+
+    printf("Searching for 2\n");
+    node = find_node(llist, 2);
+    print_node(node);
+
+    printf("Deleting node 2\n");
+    delete_node(&llist, node);
+
+    printf("Searching for 2\n");
+    node = find_node(llist, 2);
+    print_node(node);
+    printf("\n");
+
+    printf("Searching for 5\n");
+    node = find_node(llist, 5);
+    print_node(node);
+
+    printf("Deleting node 5\n");
+    delete_node(&llist, node);
+
+    printf("Searching for 5\n");
+    node = find_node(llist, 5);
+    print_node(node);
+    printf("\n");
+
+    printf("Searching for 22\n");
+    node = find_node(llist, 22);
+    print_node(node);
+
+    printf("Deleting node 22\n");
+    delete_node(&llist, node);
+
+    printf("Searching for 22\n");
+    node = find_node(llist, 22);
+    print_node(node);
+    printf("\n");
+
+    printf("Purging list\n");
+    process_list(llist, free_data);
+    purge_list(&llist);
+
+    printf("Printing entire list\n");
+    process_list(llist, print_node);
+    printf("\n");
+
+}

labs/cs2106/labs/lab4/linkedlist/testmalloc.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include "mymalloc.h"
+
+void testalloc(long size, char *ptrname, char **ptr) {
+    printf("\nAllocating %ld bytes to %s\n", size, ptrname);
+    *ptr = mymalloc(size);
+
+    if(*ptr == NULL)
+        printf("Allocation failed.\n");
+    print_memlist();
+}
+
+void testfree(char *ptr, char *ptrname) {
+    printf("\nFreeing %s\n", ptrname);
+    myfree(ptr);
+    print_memlist();
+}
+
+int main() {
+    char *ptr1, *ptr2, *ptr3, *ptr4, *ptr5;
+
+    testalloc(2048, "ptr1", &ptr1);
+    testalloc(6144, "ptr2", &ptr2);
+    testalloc(1024, "ptr3", &ptr3);
+    testfree(ptr2, "ptr2");
+    testalloc(2048, "ptr2", &ptr2);
+    testalloc(4096, "ptr4", &ptr4);
+    testfree(ptr2, "ptr2");
+    testalloc(3072, "ptr5", &ptr5);
+    testfree(ptr1, "ptr1");
+    testfree(ptr2, "ptr2");
+    testfree(ptr3, "ptr3");
+    testfree(ptr4, "ptr4");
+    testfree(ptr5, "ptr5");
+
+}

labs/cs2106/labs/lab4/linkedlist/wf/Makefile

@@ -0,0 +1,13 @@
+.PHONY: run test
+
+run: harness-wf
+	./harness-wf
+
+test: testmalloc
+	./testmalloc
+
+harness-wf: harness-wf.c llist.c mymalloc.c
+	gcc $^ -o $@
+
+testmalloc: testmalloc.c mymalloc.c llist.c
+	gcc $^ -o $@

labs/cs2106/labs/lab4/linkedlist/wf/harness-wf.c

@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <assert.h>
+#include "mymalloc.h"
+
+void *runmalloc(size_t len, long expected_ndx) {
+
+    long ndx;
+    void *ptr;
+
+    printf("Allocate %ld bytes.\n", len);
+    printf("Before: ");
+    print_memlist();
+    printf("\n");
+    ptr = mymalloc(len);
+    ndx = get_index((void *) ptr);
+    printf("EXPECTED: %ld ACTUAL: %ld\n", expected_ndx, ndx);
+    printf("After:  ");
+    print_memlist();
+    printf("\n");
+    assert(ndx == expected_ndx);
+    return ptr;
+}
+
+void runfree(void *ptr) {
+    printf("Free\n");
+    printf("Before: ");
+    print_memlist();
+    printf("\n");
+    myfree(ptr);
+    printf("After:  ");
+    print_memlist();
+    printf("\n");
+}
+
+int main() {
+    
+    void *ptr1, *ptr2, *ptr3, *ptr4, *ptr5;
+
+    ptr1 = runmalloc(4, 0);
+    ptr2 = runmalloc(32, 4);
+    ptr3 = runmalloc(2, 36);
+    runfree(ptr2);
+    ptr2 = runmalloc(12, 38);
+    ptr4 = runmalloc(24, 50);
+    ptr5 = runmalloc(18, 74);
+    runfree(ptr1);
+    ptr1 = runmalloc(2, 92);
+    runfree(ptr1);
+    runfree(ptr2);
+    runfree(ptr3);
+    runfree(ptr4);
+    runfree(ptr5);
+}
+
+

labs/cs2106/labs/lab4/linkedlist/wf/llist.c

@@ -0,0 +1,239 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "llist.h"
+
+//#define DEBUG       // Enable debug printing
+
+// Debug printer
+
+void dbprintf(char *format, ...) {
+#ifdef DEBUG
+    va_list args;
+
+    va_start(args, format);
+    vprintf(format, args);
+#endif
+}
+
+// Implements a double linked list.
+
+// Create a new node. You need to
+// Create your own TData node, populate
+// it, then create a new node with a suitable
+// key. Insertion into the link list is
+// by ascending order of the key. An example key
+// might be the starting address of a memory segment.
+
+TNode *make_node(unsigned int key, TData *data) {
+    TNode *node = malloc(sizeof(TNode));
+    node->key = key;
+    node->pdata = data;
+    node->prev = NULL;
+    node->next = NULL;
+
+    return node;
+}
+
+// Inserts a node into the correct point of the
+// double linked list. The list is sorted
+// in ascending order of the key. Duplicate keys
+// are permitted, though not recommended.
+// llist = Pointer to link list
+// node = Pointer to node created by make_node
+// dir = 0: Insert in ascending order
+// dir = 1: Insert in descending order
+
+void insert_node(TNode **llist, TNode *node, int dir) {
+    if(*llist == NULL) {
+        *llist = node;
+        (*llist)->trav = *llist;
+        (*llist)->tail = *llist;
+    }
+    else 
+        if(((*llist)->key >= node->key && dir == 0) || (((*llist)->key <= node->key) && dir == 1)) {
+            node->next = *llist;
+            (*llist)->prev = node;
+            *llist = node;
+            (*llist)->trav = *llist;
+        }
+        else
+        {
+            TNode *trav = *llist;
+
+            if(dir == 0)
+                while(trav->next != NULL && trav->key < node->key) 
+                    trav = trav->next;
+            else if(dir == 1)
+                while(trav->next != NULL && trav->key > node->key)
+                    trav = trav->next;
+
+            if(trav->next == NULL && ((trav->key < node->key && dir == 0) || 
+                        (trav->key > node->key && dir == 1))) {
+                trav->next = node;
+                node->prev = trav;
+
+                // Set the tail
+                (*llist)->tail = node;
+            } else {
+                // Insert into the previous space
+
+                node->next = trav;
+
+                if(trav->prev != NULL) {
+                    trav->prev->next = node;
+                    node->prev = trav->prev;
+                }
+
+                if(trav->next != NULL) {
+                }
+
+                trav->prev = node;
+            }
+        }
+}
+
+// Remove a given node from the linked list
+void delete_node(TNode **llist, TNode *node) {
+
+    if(*llist == NULL || node == NULL)
+        return;
+
+    if((*llist)->key == node->key) {
+        // Node to be deleted is at the front of the list.
+        *llist = (*llist)->next;
+
+        // Ensure that we don't point to it anymore.
+        if(*llist != NULL)
+            (*llist)->prev = NULL;
+    }
+    else
+    {
+        TNode *trav = *llist;
+
+        while(trav != NULL && trav->key != node->key) 
+            trav = trav->next;
+
+        // We've found the deletion point
+        if(trav != NULL) {
+            trav->prev->next = trav->next;
+
+            if(trav->next != NULL) 
+                trav->next->prev = trav->prev;
+            else
+                (*llist)->tail = trav->prev;
+        }
+
+    }
+
+    free(node);
+}
+
+// Find a node that has the value of key
+// If there are duplicate keys, the first one encountered
+// will be returned.
+TNode *find_node(TNode *llist, unsigned int key) {
+    if(llist == NULL)
+        return NULL;
+
+    TNode *trav = llist;
+
+    while(trav != NULL && trav->key != key)
+        trav = trav->next;
+
+    return trav;
+}
+
+// Merge the node provided with either the node after or the node before.
+// You need to manage merging the data in node->pdata yourself. This code just
+// deletes the larger of the two nodes.
+// dir = 0: Merge with node before
+// dir = 1: Merge with node after
+
+void merge_node(TNode *llist, TNode *node, int dir) {
+    if(dir == 0) {
+        if(node->prev == NULL)
+            return;
+
+        delete_node(&llist, node);
+    }
+    else 
+        if(dir == 1) {
+            if(node->next == NULL)
+                return;
+
+            delete_node(&llist, node->next);
+        }
+}
+
+// Go over every element of llist, and call func
+// func prototype is void func(TNode *);
+
+void process_list(TNode *llist, void (*func)(TNode *)) {
+    TNode *trav = llist;
+    while(trav) {
+        func(trav);
+        trav = trav->next;
+    }
+
+}
+
+
+// Purge the entire list. You must
+// free any dynamic data in the TData
+// struct yourself.
+void purge_list(TNode **llist) {
+    TNode *trav = *llist, *tmp;
+    while(trav) {
+        tmp = trav->next;
+        free(trav);
+        trav = tmp;
+    }
+
+    *llist = NULL;
+}
+
+
+// Reset traverser
+// where=0 START: Resets traverser to start of list
+// where=1 END: Rsets
+void reset_traverser(TNode *llist, int where)
+{
+    if(llist == NULL)
+        return;
+
+    if(where == FRONT)
+        llist->trav = llist;
+    else
+        if(where == REAR)
+            llist->trav = llist->tail;
+}
+
+// Get the next node
+TNode *succ(TNode *llist)
+{
+    if(llist == NULL)
+        return NULL;
+
+    TNode *ret = llist->trav;
+
+    if(llist->trav != NULL)
+        llist->trav = llist->trav->next;
+
+    return ret;
+}
+
+// Get the previous node
+TNode *pred(TNode *llist)
+{
+    if(llist == NULL)
+        return NULL;
+
+    TNode *ret = llist->trav;
+
+    if(llist->trav != NULL)
+        llist->trav = llist->trav->prev;
+
+    return ret;
+}

labs/cs2106/labs/lab4/linkedlist/wf/llist.h

@@ -0,0 +1,115 @@
+#include <stdbool.h>
+#include <stdio.h>
+
+// Uncomment the next line to enable debug printing
+#define DEBUG // Enable debug printing
+
+// The debug printer; used like a normal printf, except
+// that printing can be turned off by commenting out the
+// #define DEBUG above.
+void dbprintf(char *format, ...);
+
+// You should modify this structure to hold
+// whatever you need to implement your
+// memory manager. You can delete the
+// val field. It is only used for testlist.c
+
+typedef struct td {
+  bool occupied;
+  size_t size;
+} TData;
+
+/* -----------------------------------------
+   BASIC ROUTINES
+
+   Basic linked list routines
+
+   ---------------------------------------- */
+
+// Basic double linked list node.
+
+typedef struct tn {
+  unsigned int key;
+  TData *pdata; // Pointer to the data you want to store
+
+  struct tn *trav; // Only used in the root for traversal
+  struct tn *tail; // Only used in the root for finding the end of the list
+  struct tn *prev;
+  struct tn *next;
+} TNode;
+
+// Insert Direction
+#define ASCENDING 0
+#define DESCENDING 1
+
+// Merge direction
+#define PRECEDING 0
+#define SUCCEEDING 1
+
+// Traverser position
+#define FRONT 0
+#define REAR 1
+
+// Create a new node. You need to
+// Create your own TData node, populate
+// it, then create a new node with a suitable
+// key. Insertion into the link list is
+// by ascending order of the key. An example key
+// might be the starting address of a memory segment.
+
+TNode *make_node(unsigned int key, TData *data);
+
+// Inserts a node into the correct point of the
+// double linked list. The list is sorted
+// in ascending order of the key. Duplicate keys
+// are permitted, though not recommended.
+// llist = Pointer to link list
+// node = Pointer to node created by make_node
+// dir = 0: Insert in ascending order
+// dir = 1: Insert in descending order
+
+void insert_node(TNode **llist, TNode *node, int dir);
+
+// Remove a given node from the linked list
+void delete_node(TNode **llist, TNode *node);
+
+// Find a node that has the value of key
+// If there are duplicate keys, the first one encountered
+// will be returned.
+TNode *find_node(TNode *llist, unsigned int key);
+
+// Merge the node provided with either the node after or the node before.
+// You need to manage merging the data in node->pdata yourself. This code just
+// deletes the larger of the two nodes.
+// dir = 0: Merge with node before
+// dir = 1: Merge with node after
+
+void merge_node(TNode *llist, TNode *node, int dir);
+
+// Purge the entire list. You must
+// free any dynamic data in the TData
+// struct yourself.
+void purge_list(TNode **llist);
+
+/* -----------------------------------------
+   TRAVERSAL ROUTINES
+
+   Lets you traverse the linked list
+
+   ---------------------------------------- */
+
+// Go over every element of llist, and call func
+// func prototype is void func(TNode *);
+
+void process_list(TNode *llist, void (*func)(TNode *));
+
+// Reset traverser
+// where=0 START: Resets traverser to start of list
+// where=1 END: Rsets
+void reset_traverser(TNode *llist, int where);
+
+// Get the next node
+TNode *succ(TNode *llist);
+
+// Get the previous node
+TNode *pred(TNode *llist);

labs/cs2106/labs/lab4/linkedlist/wf/mymalloc.c

@@ -0,0 +1,103 @@
+#include "mymalloc.h"
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/_types/_null.h>
+
+#include "llist.h"
+
+char _heap[MEMSIZE] = {0};
+TNode *_memlist = NULL; // To maintain information about length
+
+// Do not change this. Used by the test harness.
+// You may however use this function in your code if necessary.
+long get_index(void *ptr) {
+  if (ptr == NULL)
+    return -1;
+  else
+    return (long)((char *)ptr - &_heap[0]);
+}
+
+// Allocates size bytes of memory and returns a pointer
+// to the first byte.
+void *mymalloc(size_t size) {
+  if (_memlist == NULL) {
+    TData *data = malloc(sizeof(TData));
+    data->occupied = false;
+    data->size = MEMSIZE;
+    _memlist = make_node(0, data);
+  }
+
+  // loop through the list to find a free block
+  // if found, split the block and return the pointer
+  // if not found, return NULL
+  TNode *curr = _memlist;
+  TNode *best = NULL;
+  while (curr != NULL) {
+    if (curr->pdata->occupied == true) {
+      curr = curr->next;
+      continue;
+    }
+    if (curr->pdata->size < size) {
+      curr = curr->next;
+      continue;
+    }
+    if (best == NULL) {
+      best = curr;
+      curr = curr->next;
+      continue;
+    }
+    if (best->pdata->size < curr->pdata->size) {
+      best = curr;
+      curr = curr->next;
+      continue;
+    }
+    curr = curr->next;
+  }
+  if (best == NULL)
+    return NULL;
+  best->pdata->occupied = true;
+  if (best->pdata->size > size) {
+    // 	Create a new node with the leftover space
+    TData *newData = malloc(sizeof(TData));
+    newData->occupied = false;
+    newData->size = best->pdata->size - size;
+    TNode *newNode = make_node(best->key + size, newData);
+    // insert new node after the current one in the list.
+    insert_node(&_memlist, newNode, 0);
+    // change the size of the current node.
+    best->pdata->size = size;
+  }
+  return &_heap[best->key];
+}
+
+// Frees memory pointer to by ptr.
+void myfree(void *ptr) {
+  if (ptr == NULL)
+    return;
+  long index = get_index(ptr);
+  TNode *node = find_node(_memlist, index);
+  if (node == NULL)
+    return;
+  node->pdata->occupied = false;
+  // merge with the next node if it is free
+  while (node->next != NULL && node->next->pdata->occupied == false) {
+    node->pdata->size += node->next->pdata->size;
+    merge_node(_memlist, node, 1);
+  }
+
+  while (node->prev != NULL && node->prev->pdata->occupied == false) {
+    TNode *prev = node->prev;
+    prev->pdata->size += node->pdata->size;
+    merge_node(_memlist, node, 0);
+  }
+}
+
+void print_node(TNode *node) {
+  printf("Status: %s Start index: %d Length: %zu\n",
+         node->pdata->occupied ? "ALLOCATED" : "FREE", node->key,
+         node->pdata->size);
+}
+
+void print_memlist() { process_list(_memlist, print_node); }

labs/cs2106/labs/lab4/linkedlist/wf/mymalloc.h

@@ -0,0 +1,7 @@
+#include <stdio.h>
+#define MEMSIZE 64 * 1024 // Size of memory in bytes
+
+long get_index(void *ptr);
+void print_memlist();
+void *mymalloc(size_t);
+void myfree(void *);

labs/cs2106/labs/lab4/linkedlist/wf/testmalloc.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include "mymalloc.h"
+
+void testalloc(long size, char *ptrname, char **ptr) {
+    printf("\nAllocating %ld bytes to %s\n", size, ptrname);
+    *ptr = mymalloc(size);
+
+    if(*ptr == NULL)
+        printf("Allocation failed.\n");
+    print_memlist();
+}
+
+void testfree(char *ptr, char *ptrname) {
+    printf("\nFreeing %s\n", ptrname);
+    myfree(ptr);
+    print_memlist();
+}
+
+int main() {
+    char *ptr1, *ptr2, *ptr3, *ptr4, *ptr5;
+
+    testalloc(2048, "ptr1", &ptr1);
+    testalloc(6144, "ptr2", &ptr2);
+    testalloc(1024, "ptr3", &ptr3);
+    testfree(ptr2, "ptr2");
+    testalloc(2048, "ptr2", &ptr2);
+    testalloc(4096, "ptr4", &ptr4);
+    testfree(ptr2, "ptr2");
+    testalloc(3072, "ptr5", &ptr5);
+    testfree(ptr1, "ptr1");
+    testfree(ptr2, "ptr2");
+    testfree(ptr3, "ptr3");
+    testfree(ptr4, "ptr4");
+    testfree(ptr5, "ptr5");
+
+}